Nitrosyl complexes, metal nitrosyls

1. Metal Nitrosyls and their
derivatives:
Subtitles:
 Definition.
 Classification
 Preparation
 Uses

2. Definition:
 Compounds that contain nitric oxide as NO+ ion, NO- ion or as
neutral molecule are known as nitrosyl compounds.
 Coordination compounds containing coordinated NO+ group
are called metal nitrosyls.
metal nitrosyl compound.

3. Structure:
 Studies shows that NOCl molecule is bent with N-O and N-Cl
bond distances equal to 1.14 Ao and 1.95 Ao respectively and
ONCl bond angle is equal to 115o.
 High value of dipole moment = 1.83 D measured in CCl4
suggest that N-Cl bond has some iconic character.
 Covalent structure of NOCl have V- shape which results from
sp2 hybridization.
N
O Cl

4. Classification of Nitrosyl Compounds:
 It can be classified into three classes:
I. Nitrosyl compounds containing NO+ group. e.g. Nitrosyl
halides.
II. Nitrosyl containing NO- group. e.g. Sodium nitrosyl Na[NO-
].
III. Coordination compounds containing coordinated NO+
group: metal nitrosyls

5. Metal Nitrosyls:
 Coordination compounds containing coordinated NO+
group: metal nitrosyls.
 Metal nitrosyls are coordinated compounds in which NO
molecule is attached as NO+ ion to a metal atom or ion.
 In these compounds NO+ ion which is known as nitrosonium
or nitrosyl cation acts as a ligand.
 The coordination compounds of transition metal containing
NO+ ion as ligand are called metal nitrosyls.

6. Examples of Metal Nitrosyls:
Metal Nitrosyl carbonyls:
Important examples of this
class re as follow: {Co(NO+)(CO)3} , {Mn-(NO+)(CO)4} etc.
Metal Nitrosyl Halides:
These compounds are
represented as: {Fe-(NO+)2I}2, {Fe(NO+)I}, {MI(NO+)X}, {Co-
(NO+)2X} etc.

7. Metal Nitrosyl Thio-complexes:
Coordinated
compounds are given by only Fe, Co and Ni. Examples are
M+{Fe-(NO+)2S}- etc.
Metal Nitrosyl Cyano complexes:
These complexes
are as follow: [Mn+(NO+)(CN)5]2-. Among these
[Fe(NO+)(CN)5]2- is most important.
Miscallaneous Metal Nitrosyls:
Nitrosyls like
[Co+(NO+)(NH3)5]2+, [Fe+(NO+)]2+ etc. are in this class.

8. Preparation:
 Metal Nitrosyl Carbonyls:
It can be prepared by the action
of NO on metal carbonyls.
Fe(CO)5 + 2NO Fe(CO)2(NO)2 + 3CO
Fe3(CO)12 + 6NO 3Fe(CO)2(NO)2 + 6CO
 Metal Nitrosyl Halides:
Prepared by the action of NO on
metal halides in the presence of suitable metal which acts as a
halogen acceptor.
2NiI2 + 2NO + Zn 2[Ni(NO)I] + ZnI2

9. CoX2 + 4NO + Co 2[Co(NO)2X]
Sodium Nitroprusside:
It can be prepared by warming a
solution of potassium ferrocyante with 50% HNO3 till a brown
solution is obtained.
K4[Fe(CN)6] + 4HNO3 H4[Fe(CN)6] + 4KNO3
H3[Fe(CN)6] + NO H2[Fe(NO)(CN)5] + HCN

10. USES:
 Metal nitrisyls are assumed to be intermediated in catalytic
converters.
 In biology nitric oxide is an important signalling molecule in
nature.
 Nitric oxide also attacks iron sulphur proteins giving dinitrosyl
iron complexes.

11. Thank You.