Chemistry test - complex compounds - URGENT! and got the best answer

Answer from Nick[guru]
Some questions were asked incorrectly, for example 7,12,27. Therefore, the answers contain caveats.
1. What is the coordination number of the complexing agent in the +2 complex ion?
AT 6
2. What is the coordination number of the complexing agent in the complex ion 2+?
B) 6
3. What is the coordination number of the complexing agent in the complex ion 2+
B) 4
4. What is the coordination number of Cu²+ in the complex ion +?
B) 4
5. What is the coordination number of the complexing agent in the complex ion: +4?
B) 6
6. Determine the charge of the central ion in the complex compound K4
B) +2
7. What is the charge of a complex ion?
B) +2 – if we assume that the complexing agent is Cu (II)
8. Among the iron salts, identify the complex salt:
A) K3
9. What is the coordination number of Pt4+ in the complex 2+ ion?
A) 4
10. Determine the charge of the complex ion K2?
B) +2
11. Which molecule corresponds to the name tetraammine copper(II) dichloride?
B) Cl2
12. What is the charge of a complex ion?
D) +3 – if we assume that the complexing agent is Cr (III)
13. Among copper (II) salts, determine the complex salt:
B) K2
14. What is the coordination number of Co3+ in the complex ion +?
B) 6
15. Determine the charge of the complexing agent in complex compound K3?
D) +3
16. Which molecule corresponds to the name potassium tetraiodohydrate (II)?
A) K2
17. What is the charge of a complex ion?
AT 2
18. Among nickel (II) salts, identify the complex salt:
B) SO4
19. What is the coordination number of Fe3+ in the complex ion -3?
AT 6
20. Determine the charge of the complexing agent in complex compound K3?
B) +3
21. Which molecule corresponds to the name silver diamine chloride (I)?
B) Cl
22. What is the charge of the K4 complex ion?
B) -4
23. Among the zinc salts, identify the complex salt
B) Na2
24. What is the coordination number of Pd4+ in the 4+ complex ion?
D) 6
25. Determine the charge of the complexing agent in the complex compound H2?
B) +2
26. Which molecule corresponds to the name potassium hexacyanoferrate (II)?
D) K4
27. What is the charge of a complex ion?
D) -2 – if we assume that the complexing agent is Co (II)
27. Among chromium (III) compounds, identify the complex compound
B) [Cr (H2O) 2(NH3)4]Cl3
28. What is the coordination number of cobalt (III) in the NO3 complex ion?
B) 6
29. Determine the charge of the complexing agent in the complex compound Cl2
A) +3
30. Which molecule corresponds to the name sodium tetraiodopalladate (II)?
D) Na2

Answer from James Bond[newbie]
Oh my God

Answer from Kitten...[guru]
No. 30 last

Complex connections

Lecture lesson notes

Goals. To form ideas about the composition, structure, properties and nomenclature of complex compounds; develop skills in determining the oxidation state of a complexing agent and drawing up dissociation equations for complex compounds.
New concepts: complex compound, complexing agent, ligand, coordination number, outer and inner spheres of the complex.
Equipment and reagents. A rack with test tubes, concentrated ammonia solution, solutions of copper(II) sulfate, silver nitrate, sodium hydroxide.

DURING THE CLASSES

Laboratory experience. Add ammonia solution to the copper(II) sulfate solution. The liquid will turn an intense blue color.

What happened? Chemical reaction? Until now, we didn't know that ammonia could react with salt. What substance was formed? What is its formula, structure, name? What class of compounds does it belong to? Can ammonia react with other salts? Are there connections similar to this? We have to answer these questions today.

To better study the properties of some compounds of iron, copper, silver, aluminum, we need knowledge about complex compounds.

Let's continue our experience. Divide the resulting solution into two parts. Add lye to one part. Precipitation of copper(II) hydroxide Cu(OH) 2 is not observed, therefore, there are no doubly charged copper ions in the solution or there are too few of them. From this we can conclude that copper ions interact with the added ammonia and form some new ions that do not form an insoluble compound with OH – ions.

At the same time, the ions remain unchanged. This can be verified by adding a solution of barium chloride to the ammonia solution. A white precipitate of BaSO 4 will immediately form.

Research has shown that dark blue color ammonia solution is due to the presence of complex 2+ ions in it, formed by the addition of four ammonia molecules to the copper ion. When water evaporates, 2+ ions bind to ions, and dark blue crystals are released from the solution, the composition of which is expressed by the formula SO 4 H 2 O.

Complex compounds are those containing complex ions and molecules capable of existing both in crystalline form and in solutions.

The formulas of molecules or ions of complex compounds are usually enclosed in square brackets. Complex compounds are obtained from ordinary (non-complex) compounds.

Examples of obtaining complex compounds

The structure of complex compounds is considered on the basis of the coordination theory proposed in 1893 by the Swiss chemist Alfred Werner, Nobel Prize winner. His scientific activity took place at the University of Zurich. The scientist synthesized many new complex compounds, systematized previously known and newly obtained complex compounds, and developed experimental methods for proving their structure.

A. Werner (1866–1919)

In accordance with this theory, complex compounds are distinguished complexing agent, external And inner sphere. The complexing agent is usually a cation or neutral atom. The inner sphere consists of a certain number of ions or neutral molecules that are tightly bound to the complexing agent. They are called ligands. The number of ligands determines coordination number(CN) complexing agent.

Example of a complex compound

The compound SO 4 H 2 O or CuSO 4 5H 2 O considered in the example is a crystalline hydrate of copper(II) sulfate.

Let's determine the components of other complex compounds, for example K 4.
(Reference. A substance with the formula HCN is hydrocyanic acid. Salts of hydrocyanic acid are called cyanides.)

The complexing agent is the iron ion Fe 2+, the ligands are cyanide ions CN –, the coordination number is six. Everything written in square brackets is the inner sphere. Potassium ions form the outer sphere of the complex compound.

The nature of the bond between the central ion (atom) and the ligands can be twofold. On the one hand, the connection is due to the forces of electrostatic attraction. On the other hand, between the central atom and the ligands a bond can be formed by a donor-acceptor mechanism, similar to the ammonium ion. In many complex compounds, the bond between the central ion (atom) and the ligands is due to both the forces of electrostatic attraction and the bond formed due to the lone electron pairs of the complexing agent and the free orbitals of the ligands.

Complex compounds having an outer sphere are strong electrolytes and in aqueous solutions dissociate almost completely into a complex ion and ions external sphere. For example:

SO 4 2+ + .

During exchange reactions, complex ions move from one compound to another without changing their composition:

SO 4 + BaCl 2 = Cl 2 + BaSO 4.

The inner sphere can have a positive, negative or zero charge.

If the charge of the ligands compensates for the charge of the complexing agent, then such complex compounds are called neutral or non-electrolyte complexes: they consist only of the complexing agent and inner sphere ligands.

Such a neutral complex is, for example, .

The most typical complexing agents are cations d-elements.

Ligands can be:

a) polar molecules - NH 3, H 2 O, CO, NO;
b) simple ions – F – , Cl – , Br – , I – , H – , H + ;
c) complex ions – CN –, SCN –, NO 2 –, OH –.

Let's consider a table that shows the coordination numbers of some complexing agents.

Nomenclature of complex compounds. The anion in a compound is called first and then the cation. When indicating the composition of the inner sphere, the anions are first called, adding the suffix - to the Latin name. O-, for example: Cl – – chloro, CN – – cyano, OH – – hydroxo, etc. Hereinafter referred to as neutral ligands and primarily ammonia and its derivatives. In this case, the following terms are used: for coordinated ammonia - ammin, for water – aqua. The number of ligands is indicated in Greek words: 1 - mono, 2 - di, 3 - three, 4 - tetra, 5 - penta, 6 - hexa. Then they move on to the name of the central atom. If the central atom is part of the cations, then use the Russian name of the corresponding element and indicate its oxidation state in parentheses (in Roman numerals). If the central atom is contained in the anion, then use the Latin name of the element, and add the ending at the end - at. In the case of non-electrolytes, the oxidation state of the central atom is not given, because it is uniquely determined from the condition of electrical neutrality of the complex.

Examples. To name a complex Cl 2, determine the oxidation state (S.O.)
X complexing agent – ​​Cu ion X+ :

1 x + 2 (–1) = 0,x = +2, C.O.(Cu) = +2.

The oxidation state of the cobalt ion is determined similarly:

y + 2 (–1) + (–1) = 0,y = +3, S.O.(Co) = +3.

What is the coordination number of cobalt in this compound? How many molecules and ions surround the central ion? The coordination number of cobalt is six.

The name of a complex ion is written in one word. The oxidation state of the central atom is indicated by a Roman numeral placed in parentheses. For example:

Cl 2 – tetraammine copper(II) chloride,
NO 3 – dichloroaquatriammine cobalt(III) nitrate,
K 3 – hexacyanoferrate(III) potassium,
K 2 – tetrachloroplatinate(II) potassium,
– dichlorotetraamminzinc,
H 2 – hexachlorotanic acid.

Using the example of several complex compounds, we will determine the structure of molecules (complexing ion, its SO, coordination number, ligands, inner and outer spheres), give a name to the complex, and write down the equations of electrolytic dissociation.

K 4 – potassium hexacyanoferrate(II),

K 4 4K + + 4– .

H – tetrachlorauric acid (formed when gold is dissolved in aqua regia),

H H + + –.

OH – diamminesilver(I) hydroxide (this substance participates in the “silver mirror” reaction),

OH + + OH – .

Na – tetrahydroxoaluminate sodium,

Na Na + + – .

Complex compounds also include many organic substances, in particular, the known products of the interaction of amines with water and acids. For example, methyl ammonium chloride salts and phenylammonium chloride are complex compounds. According to coordination theory, they have the following structure:

Here the nitrogen atom is a complexing agent, the hydrogen atoms at nitrogen, the methyl and phenyl radicals are ligands. Together they form the inner sphere. The outer sphere contains chloride ions.

Many organic substances that are of great importance in the life of organisms are complex compounds. These include hemoglobin, chlorophyll, enzymes and etc.

Complex compounds are widely used:

1) in analytical chemistry for the determination of many ions;
2) for the separation of certain metals and obtaining metals of high purity;
3) as dyes;
4) to eliminate water hardness;
5) as catalysts for important biochemical processes.

Problem 723.
Name the complex salts: Cl, (NO 3) 2, CNBr, NO 3, Cl, K 4, (NH 4) 3, Na 2, K 2, K 2. K2.
Solution:
C - chlorotriamminaquapalladium (II) chloride;
(NO 3 ) 2 - tetraamine copper (I) nitrate;
CNB - tetraaminediaquacobalt(II) cyanobromide;
NO 3 - sulfatopentaammine cobalt (III) nitrate;
Cl - chlorotetraammine palladium (II) chloride;
K 4 - potassium hexacyanoferrate (II);
(NH 4 ) 3 - ammonium hexachlororodinate (II);
Na 2 - sodium tetraiodopalladinate (II);
K 2 - potassium tetranitratediammine cobaltate (II);
K 2 - potassium chloropentahydroxoplatinate (IV);
K 2 - potassium tetracyanocupriate (II).

Problem 724.
Write coordination formulas for the following complex compounds: a) potassium dicyanoargentate; b) potassium hexanitrocobaltate (III); c) hexaamminnickel (II) chloride; d) sodium hexacyanochromate (III); e) hexaammine cobalt (III) bromide; f) tetraammine carbonate sulfate (III); g) diaquatetraammine nickel nitrate (II); h) magnesium trifluorohydroxoberyllate.
Solution:
a) K - potassium dicyanoargentate;
b) K 3 - potassium hexanitrocobaltate (III);
c) Cl - hexaamminnickel (II) chloride;
d) Na 3 - sodium hexacyanochromate (III);
e) Cl 3 - hexaammine cobalt (III) bromide;
f) SO 4 2- - tetraammine carbonate sulfate (III);
g) (NO 3) 2 - diaquatetraamminnickel (II) nitrate;
h) Mg magnesium trifluorohydroxoberyllate.

Problem 725.
Name the following electrically neutral complex compounds: , , , , .
Solution:
, - tetraaquaphosphate chromium;
- dirodanodiammine copper;
- dichlorodihydroxylamine palladium;
- trinitrotriaminerhodium;
- tetrachlorodiammineplatinum.

Problem 726.
Write the formulas of the listed complex nonelectrolytes: a) tetraammine phosphatochrome; b) diammindichloroplatinum; c) triamminetrichlorocobalt; d) diammintetrachloroplatinum. In each of the complexes, indicate the degree of oxidation of the complexing agent.
Solution:
a) - tetraammine phosphatochrome. The charge of Cr is (x), NH 3 - (0), PO 4 - (-3). From here, taking into account that the sum of the particle charges is equal to (o), we find the charge of chromium: x + 4(0) + (-3) = 0; x = +3. Oxidation degree chromium is +3.

b) - diammindichloroplatinum. The charge of Pt is (x), NH 3 - (0), Cl - (-1). From here, taking into account that the sum of the particle charges is equal to (0), we find the charge of platinum: x +4(0) + 2(-1) = 0; x = +2. Oxidation degree platinum is +2.

c) - triamminetrichlorocobalt. The charge of Co is (x), NH 3 - (0), Cl - (-1). From here, taking into account that the sum of the particle charges is equal to (o), we find the charge of cobalt: x + 3(0) + 3(-1) = 0; x = +3. Oxidation degree cobalt is +3.

d) - diammintetrachloroplatinum. The charge of Pt is (x), NH 3 - (0), Cl - (-1). From here, taking into account that the sum of the particle charges is equal to (0), we find the charge of platinum: x +4(0) + 4(-1) = 0; x = +4. Oxidation degree platinum is +2.

Problem 727.
The chemical names of yellow and red blood salt are potassium hexacyanoferrate(II) and potassium hexacyanoferrate(III). Write the formulas of these salts.
Solution:
K 4 - potassium hexacyanoferrate (II) (yellow blood salt);
K 3 - potassium hexacyanoferrate (III) (red blood salt).

Problem 728.
Brick red crystals rose salts have a composition expressed by the formula Cl 3, purple salt- crimson-red crystals of Cl 2 composition. Give the chemical names of these salts.
Solution:
A) Rosesol Cl 3 is called aquapentaammine cobalt (III) chloride.
b) Purpureosol Cl 2 is called aquapentaammine cobalt (II) chloride.

The nomenclature of complex compounds is integral part nomenclature of inorganic substances. The rules for composing the names of complex compounds are systematic (unambiguous). In accordance with IUPAC recommendations, these rules are universal, since, if necessary, they can be applied to simple inorganic compounds if there are no traditional and special names for the latter. Names constructed according to systematic rules are adequate chemical formulas. The formula of a complex compound is compiled according to general rules: first the cation is written - complex or ordinary, then the anion - complex or ordinary. In the inner sphere of a complex compound, the central complexing atom is first written, then the uncharged ligands (molecules), then the negatively charged anion ligands.

Mononuclear complexes

In the names of cationic, neutral and most anionic complexes, the central atoms have the Russian names of the corresponding elements. In some cases, for anionic complexes, the roots of the Latin names of the elements of the central complex-forming atom are used. For example, – dichlorodiammineplatinum, 2- - tetrachloroplatinate(II) ion, + - diamminesilver(I) cation, - - dicyanoargenate(I) ion.

The name of a complex ion begins with the composition of the inner sphere. First of all, in alphabetical order list the anions located in the inner sphere, adding the ending “o” to their Latin name. For example, OH - - hydroxo, Cl - - chloro, CN - - cyano, CH 3 COO - - acetato, CO 3 2- - carbonato, C 2 O 4 2- - oxalato, NCS - - thiocyanato, NO 2 - - nitro , O 2 2- - oxo, S 2- - thio, SO 3 2- - sulfito, SO 3 S 2- - thiosulfato, C 5 H 5 - cyclopentadienyl, etc. The inner-sphere neutral molecules are then listed in alphabetical order. For neutral ligands, single-word names of substances are used without changes, for example N 2 -dianitrogen, N 2 H 4 -hydrazine, C 2 H 4 - ethylene. Intrasphere NH 3 is called ammino-, H 2 O - aqua, CO - carbonyl, NO - nitrosyl. The number of ligands is indicated by Greek numerals: di, tri, tetra, penta, hexa, etc. If the names of the ligands are more complex, for example, ethylenediamine, they are preceded by the prefixes “bis”, “tris”, “tetrakis”, etc.

The names of complex compounds with the outer sphere consist of two words (in general view"cation anion"). The name of the complex anion ends with the suffix –at. The oxidation state of the complexing agent is indicated in Roman numerals in parentheses after the name of the anion. For example:

K 2 – potassium tetrachloroplatinate(II),

Na 3 [Fe(NH 3)(CN) 5] – sodium pentacyanomonoamine ferrate(II),

H 3 O – oxonium tetrachloroaurate(III),

K – potassium diiodoiodate(I),

Na 2 – sodium hexahydroxostannate(IV).

In compounds with a complex cation, the oxidation state of the complexing agent is indicated after its name in Roman numerals in parentheses. For example:

Cl – diammine silver (I) chloride,

Br – trichlorotriammineplatinum(IV) bromide,

NO 3 -

Cobalt(III) chloronitrotetraammine nitrate.

The names of complex compounds—nonelectrolytes without an outer sphere—consist of one word; the oxidation state of the complexing agent is not indicated. For example:

– trifluorotriaquocobalt,

- tetrachlorodiammine platinum,

– bis(cyclopentadienyl)iron.

The name of compounds with complex cation and anion consists of the names of the cation and anion, for example:

hexanitrocobaltate(III) hexaamminecobalt(III),

trichloroammine platinate (II) chloroammine platinum(II).

For complexes with ambidentate ligands, the name indicates the symbol of the atom with which this ligand is associated with the central complex-forming atom:

2- - tetrakis(ticyanato-N) cobaltate(II) ion,

2- - tetrakis(thiocyanato-S) mercurate(II) – ion.

By tradition, the ambidentate ligand NO 2 - is called a nitro ligand if the donor atom is nitrogen, and a nitrite ligand if the donor atom is oxygen (–ONO -):

3- - hexanitrocobaltate(III)-ion,

3- - hexanitritocobaltate(III) ion.

Classification of complex compounds

Complex ions can be part of molecules of various classes of chemical compounds: acids, bases, salts, etc. Depending on the charge of the complex ion, they are distinguished cationic, anionic and neutral complexes.

Cationic complexes

In cationic complexes, the central complexing atom is cations or positively polarized complexing atoms, and the ligands are neutral molecules, most often water and ammonia. Complex compounds in which water is the ligand are called aqua complexes. These compounds include crystalline hydrates. For example: MgCl 2 × 6H 2 O

or Cl2,

CuSO 4 ×5H 2 O or ∙SO 4 ∙ H 2 O, FeSO 4 ×7H 2 O or SO 4 ×H 2 O

In the crystalline state, some aqua complexes (for example, copper sulfate) also retain water of crystallization, which is not part of the inner sphere, which is less tightly bound and easily splits off when heated.

One of the most numerous classes of complex compounds is ammino complexes (ammonics) and aminates. The ligands in these complexes are ammonia or amine molecules. For example: SO 4, Cl 4,

Cl2.

Anionic complexes

The ligands in such compounds are anions or negatively polarized atoms and their groups.

Anionic complexes include:

a) complex acids H, H2, H.

b) double and complex salts PtCl 4 × 2KCl or K 2,

HgI 2 × 2KI or K 2.

c) oxygen-containing acids and their salts H 2 SO 4, K 2 SO 4, H 5 IO 6, K 2 CrO 4.

d) hydroxosalts K, Na 2.

e) polyhalides: K, Cs.

Neutral complexes

Such compounds include complex compounds that do not have an outer sphere and do not produce complex ions in aqueous solutions: , , carbonyl complexes , .

Cation-anionic complexes

The compounds simultaneously contain both a complex cation and a complex anion:

, .

Cyclic complexes (chelates)

Coordination compounds in which the central atom (or ion) is bonded simultaneously with two or more donor atoms of the ligand, resulting in the closure of one or more heterocycles, are called chelates . Ligands that form chelate rings are called chelating reagents. The closure of the chelate cycle by such ligands is called chelation(by chelation). The most extensive and important class of chelates are metal chelate complexes. The ability to coordinate ligands is inherent in metals of all oxidation states. For elements of the main subgroups, the central complexing atom is usually in the highest oxidation state.

Chelating reagents contain two main types of electron-donating centers: a) groups containing a mobile proton, for example, -COOH, -OH, -SO 3 H; when they are coordinated to the central ion, it is possible to replace a proton and b) neutral electron-donating groups, for example R 2 CO, R 3 N. Bidentate ligands occupy two places in the internal coordination sphere of the chelate, such as ethylenediamine (Fig. 3).

According to Chugaev's rule of cycles, the most stable chelate complexes are formed when the cycle contains five or six atoms. For example, among diamines of the composition H 2 N-(CH 2)n-NH 2, the most stable complexes are formed for n=2 (five-membered ring) and n=3 (six-membered ring).

Fig.3. Copper(II) bisethylenediamine cation.

Chelates in which, upon closing the chelate ring, the ligand uses proton-containing and neutral electron-donating groups and is formally bonded to the central atom by a covalent and donor-acceptor bond are called there are intra-complex compounds. Thus, polydentate ligands with acidic functional groups can form intracomplex compounds. Intracomplex compounds are a chelate in which the closure of the cycle is accompanied by the displacement of one or more protons from acidic functional groups by a metal ion, in particular, the intracomplex compound is copper(II) glycinate:

Fig.4. Intracomplex compound of 8-hydroxyquinoline with zinc.

Hemoglobin and chlorophyll are also intracomplex compounds.

The most important feature of chelates is their increased stability compared to similarly constructed non-cyclic complexes.

All inorganic compounds are divided into two groups:

1. first order connections, i.e. compounds subject to the valence theory;

2. higher order connections, i.e. compounds that do not obey the concepts of valence theory. Higher order compounds include hydrates, ammonia, etc.

CoCl 3 + 6 NH 3 = Co(NH 3) 6 Cl 3

Werner (Switzerland) introduced the concept of higher-order compounds into chemistry and gave them the name complex compounds. He classified as CS all the most stable compounds of higher order, which in an aqueous solution either do not decompose into their component parts at all, or decompose to an insignificant extent. In 1893, Werner suggested that any element, after saturation, can also exhibit additional valency - coordination. According to Werner’s coordination theory, in each CS there are distinguished:

Cl 3: complexing agent (CO = Co), ligands (NH 3), coordination number (CN = 6), inner sphere, external environment (Cl 3), coordination capacity.

The central atom of the inner sphere around which ions or molecules are grouped is called complexing agent. The role of complexing agents is most often performed by metal ions, less often by neutral atoms or anions. Ions or molecules that coordinate around a central atom in the inner sphere are called ligands. Ligands can be anions: G -, OH-, CN-, CNS-, NO 2 -, CO 3 2-, C 2 O 4 2-, neutral molecules: H 2 O, CO, G 2, NH 3, N 2 H4. Coordination number is the number of sites in the internal sphere of the complex that can be occupied by ligands. The CN is usually higher than the oxidation state. CN = 1, 2, 3, 4, 5, 6, 7, 8, 9, 12. The most common CN = 4, 6, 2. These numbers correspond to the most symmetrical configuration of the complex - octahedral (6), tetrahedral (4) and linear (2). CC depending on the nature of the complexing agent and ligands, as well as on the size of the CO and ligands. Coordination capacity of ligands is the number of sites in the internal sphere of the complex occupied by each ligand. For most ligands, the coordination capacity is equal to unity ( monodentate ligands), less often two ( bidentate ligands), there are ligands with greater capacity (3, 4,6) – polydentate ligands. The charge of the complex must be numerically equal to the total charge of the outer sphere and opposite in sign. 3+ Cl 3 - .

Nomenclature of complex compounds. Many complex compounds have retained their historical names, associated with the color or the name of the scientist who synthesized them. The IUPAC nomenclature is currently used.

Order of listing ions. The anion is called first, then the cation, while the name of the anion uses the root of the Latin name KO, and the name of the cation uses its Russian name in the genitive case.

Cl—diammine silver chloride; K 2 – potassium trichlorocuprate.

Order of listing of ligands. Ligands in the complex are listed in the following order: anionic, neutral, cationic - without separation by a hyphen. Anions are listed in the order H -, O 2-, OH -, simple anions, complex anions, polyatomic anions, organic anions.

SO 4 – chloronitrsulfate (+4)

End of coordination groups. Neutral groups are called the same as molecules. The exceptions are aqua (H 2 O), amine (NH 3). The vowel “O” is added to negatively charged anions.

– hexocyanoferrate (+3) cobalt hexaamine (+3)

Prefixes indicating the number of ligands.

1 - mono, 2 - di, 3 - three, 4 - tetra, 5 - penta, 6 - hexa, 7 - hepta, 8 - octa, 9 - nona, 10 - deca, 11 - indeca, 12 - dodeca, many - poly.

The prefixes bis-, tris- are used before ligands with complex names, where there are already prefixes mono-, di-, etc.

Cl 3 – tris(ethylenediamine)iron chloride (+3)

In the names of complex compounds, the anionic part is indicated first in the nominative case and with the suffix -at, and then the cationic part in the genitive case. However, before the name of the central atom in both the anionic and cationic parts of the compound, all ligands coordinated around it are listed, indicating their number in Greek numerals (1 - mono (usually omitted), 2 - di, 3 - three, 4 - tetra, 5 - penta, 6 - hexa, 7 - hepta, 8 - octa). The suffix -o is added to the names of the ligands, and the anions are named first, and then the neutral molecules: Cl- - chloro, CN- - cyano, OH- - hydroxo, C2O42- - oxalato, S2O32- - thiosulfato, (CH3)2NH - dimethylamino and etc. Exceptions: The names of H2O and NH3 as ligands are “aqua” and “ammin”. If the central atom is part of a cation, then the Russian name of the element is used, after which its oxidation state is indicated in parentheses in Roman numerals. For the central atom in the anion, the Latin name of the element is used and the oxidation state is indicated before this name. For elements with a constant oxidation state it can be omitted. In the case of nonelectrolytes, the oxidation state of the central atom is also not indicated, since it is determined based on the electrical neutrality of the complex. Examples of names:

Cl2 - dichloro-tetrammine-platinum(IV) chloride,

OH - diammine-silver(I) hydroxide.

Classification of complex compounds. Several different classifications of CS are used.

1. by belonging to a certain class of compounds:

complex acids – H 2

complex foundations –

complex salts – K 2

2. By the nature of the ligands: aqua complexes, ammonia. Cyanide, halide, etc.

Aqua complexes are complexes in which water molecules serve as ligands, for example Cl 2 - hexaquacalcium chloride. Ammonia and aminates are complexes in which the ligands are molecules of ammonia and organic amines, for example: SO 4 - tetrammine copper(II) sulfate. Hydroxo complexes. In them, OH- ions serve as ligands. Particularly characteristic of amphoteric metals. Example: Na 2 - sodium tetrahydroxocinate(II). Acid complexes. In these complexes, the ligands are anion-acid residues, for example K 4 - potassium hexacyanoferrate(II).

3. according to the sign of the charge of the complex: cationic, anionic, neutral

4. by internal structure KS: by the number of nuclei making up the complex:

mononuclear - H 2, binuclear - Cl 5, etc.,

5. by the absence or presence of cycles: simple and cyclic CS.

Cyclic or chelate (claw-shaped) complexes. They contain a bi- or polydentate ligand, which seems to grab the central M atom like claws of a cancer: Examples: Na 3 - sodium trioxalato-(III) ferrate, (NO 3) 4 - triethylenediamine-platinum(IV) nitrate.

The group of chelate complexes also includes intracomplex compounds in which the central atom is part of the cycle, forming bonds with ligands different ways: by exchange and donor-acceptor mechanisms. Such complexes are very characteristic of aminocarboxylic acids, for example, glycine forms chelates with Cu 2+ and Pt 2+ ions:

Chelate compounds are particularly strong, since the central atom in them is, as it were, blocked by a cyclic ligand. Chelates with five- and six-membered rings are most stable. Complexons bind metal cations so strongly that when they are added, poorly soluble substances such as CaSO 4, BaSO 4, CaC 2 O 4, CaCO 3 dissolve. Therefore, they are used to soften water, to bind metal ions during dyeing, processing photographic materials, and in analytical chemistry. Many chelate-type complexes have a specific color and therefore the corresponding ligand compounds are very sensitive reagents for transition metal cations. For example, dimethylglyoxime [C(CH 3)NOH] 2 serves as an excellent reagent for the cations Ni2+, Pd2+, Pt2+, Fe2+, etc.

Stability of complex compounds. Instability constant. When the CS is dissolved in water, decomposition occurs, and the inner sphere behaves as a single whole.

K = K + + -

Along with this process, dissociation of the internal sphere of the complex occurs to a small extent:

Ag + + 2CN -

To characterize the stability of the CS, we introduce instability constant, equal to:

The instability constant is a measure of the strength of the CS. The lower the K nest, the stronger the KS.

Isomerism of complex compounds. For complex compounds, isomerism is very common and is distinguished:

1. solvate isomerism is found in isomers when the distribution of water molecules between the inner and outer spheres is unequal.

Cl 3 Cl 2 H 2 O Cl(H 2 O) 2

Purple light green dark green

2.Ionization isomerism is associated with different ease of dissociation of ions from the inner and outer spheres of the complex.

4 Cl 2 ]Br 2 4 Br 2 ]Cl 2

SO 4 and Br - bromo-pentammine-cobalt(III) sulfate and bromo-pentammine-cobalt(III) sulfate.

Cl and NO 2 - chloride-nitro-chloro-diethylenediamine-cobalt(III) initritedichloro-diethylenediamine-cobalt(III).

3. Coordination isomerism occurs only in bicomplex compounds

[Co(NH 3) 6 ] [Co(CN) 6 ]

Coordination isomerism occurs in those complex compounds where both the cation and the anion are complex.

For example, - tetrammine-chromium(II) tetrachloro-(II)platinate and - tetrammine-platinum(II) tetrachloro-(II)chromate are coordination isomers

4. Communication isomerism occurs only when monodentate ligands can coordinate through two different atoms.

5. Spatial isomerism due to the fact that identical ligands are located around the KO or nearby (cis), or opposite ( trance).

Cis isomer (orange crystals) trans isomer (yellow crystals)

Isomers of dichloro-diammine-platinum

With a tetrahedral arrangement of ligands, cis-trans isomerism is impossible.

6. Mirror (optical) isomerism, for example in the dichloro-diethylenediamine-chromium(III) + cation:

As in the case of organic substances, mirror isomers have the same physical and Chemical properties and differ in the asymmetry of the crystals and the direction of rotation of the plane of polarization of light.

7. Ligand isomerism for example, for (NH 2) 2 (CH 2) 4 the following isomers are possible: (NH 2)-(CH 2) 4 -NH 2, CH 3 -NH-CH 2 -CH 2 -NH-CH 3, NH 2 -CH(CH 3) -CH 2 -CH 2 -NH 2

Communication problem in complex connections. The nature of the connection in the CS is different and three approaches are currently used for explanation: the BC method, the MO method and the crystal field theory method.

BC method Pauling introduced. Basic principles of the method:

1. The bond in the CS is formed as a result of donor-acceptor interaction. Ligands provide electron pairs, and the complexing agent provides free orbitals. A measure of bond strength is the degree of orbital overlap.

2. KO orbitals undergo hybridization, the type of hybridization is determined by the number, nature and electronic structure of the ligands. Hybridization of CO is determined by the geometry of the complex.

3. Additional strengthening of the complex occurs due to the fact that, along with the s-bond, a p-bond is formed.

4. The magnetic properties of the complex are determined by the number of unpaired electrons.

5. When a complex is formed, the distribution of electrons in orbitals can remain with neutral atoms or undergo changes. It depends on the nature of the ligands and its electrostatic field. A spectrochemical series of ligands has been developed. If the ligands have a strong field, then they displace electrons, causing them to pair and form a new bond.

Spectrochemical series of ligands:

CN - >NO 2 - >NH 3 >CNS - >H 2 O>F - >OH - >Cl - >Br -

6. The BC method makes it possible to explain the formation of bonds even in neutral and classer complexes

K 3 K 3

1. At the first CS, ligands are created strong field, the second one has a weak

2. Draw the valence orbitals of iron:

3. Consider the donor properties of ligands: CN - have free electron orbitals and can be donors of electron pairs. CN - has a strong field, acts on 3d orbitals, densifying them.

As a result, 6 bonds are formed, with internal 3 d orbitals participating in the bond, i.e. an intraorbital complex is formed. The complex is paramagnetic and low-spin, because there is one unpaired electron. The complex is stable, because the inner orbitals are occupied.

F ions have free electron orbitals and can be donors of electron pairs, they have a weak field, and therefore cannot compact electrons at the 3d level.

As a result, a paramagnetic, high-spin, outer-orbital complex is formed. Unstable and reactive.

Advantages of the BC method: information content

Disadvantages of the BC method: the method is suitable for a certain range of substances, the method does not explain the optical properties (color), does not provide an energy assessment, because in some cases, a quadratic complex is formed instead of the more energetically favorable tetrahedral one.