What are ambidentate ligands?

The ligands which can attach to the central metal atom through atoms of two different elements are called ambidentate ligands. Examples are cyanide ( CN - ) and nitrite ( NO 2 - ).

Explain why Co NH 3 6 3 + is an inner orbital complex, whereas Ni NH 3 6 2 + is an outer orbital complex. (Atomic numbers of Co and Ni are 27 and 28 , respectively)

The central metal ion, cobalt of the complex ion Co NH 3 6 3 + is in + 3 oxidation state with the outermost electronic configuration 3 d 6 4 s 0 . In the presence of ammine ligands, 3 d -electrons pair up leaving two d -orbitals empty. Hence, the hybridisation is d 2 sp 3 forming an inner orbital complex. In Ni NH 3 6 2 + , nickel is in + 2 oxidation state and has configuration 3 d 8 . In the presence of ammine ligands, the 3 d -electrons do not pair up. The hybridisation is sp 3 d 2 forming an outer orbital complex.

Write the structures of the geometrical isomers of Co NH 3 3 Cl 3 .

Two types of geometrical isomers are possible for the complex Co NH 3 3 Cl 3 . If three donor atoms of the same ligands occupy adjacent positions at the corners of an octahedral face, it is called as facial (fac) isomer. When the positions are around the meridian of the octahedron, we get the meridional (mer) isomer.

What is crystal field splitting?

The splitting of degenerate orbitals of central metal atom or ion in a complex molecule by the ligands into orbitals of different energy is called crystal field splitting.

Write the IUPAC name of Ag NH 3 2 Ag CN 2 .

In the complex molecule, Ag NH 3 2 Ag CN 2 both positive and negative part are complex ions. According to IUPAC rules, the positive part is named first starting from the ligands followed by the name of the metal ion as such with the oxidation number of the metal ion. Then the negative part is named similar to the positive ion, however, the name of the metal ends with -ate. There are two neutral ammine ligands, and two negative cyano ligands. Therefore, the IUPAC name of Ag NH 3 2 Ag CN 2 becomes diamminesilver( I ) dicyanidoargentate( I ).

Calculate the coordination number of Co in Co en 3 3 + .

Coordination number is the number of ligating atoms to which a central metal ion or atom is directly bonded through coordinate bonds. In the complex ion Co en 3 3 + , the ligand ethane- 1 , 2 -diamine (en) is a bidentate ligand, hence the coordination number of cobalt ion is six ( 2 × 3 = 6 ).

Is the complex [ Ni ( CO ) 4 ] a low-spin or a high-spin complex? Explain on the basis of VBT.

The oxidation state of nickel in this complex is zero as CO is a neutral strong field ligand. Therefore, its electronic configuration is [ Ar ] 3 d 8 4 s 2 . Hence, we have, From the above orbital representation it is clear that the complex has no unpaired electrons, so, this is a low spin complex.

Name the type of isomerism exhibited by the following pairs of complexes: (i) [ Co ( NH 3 ) 6 ] [ Cr ( CN ) 6 ] and [ Cr ( NH 3 ) 6 ] [ Co ( CN ) 6 ] (ii) [ Co ( NH 3 ) 5 SO 4 ] Br and [ Co ( NH 3 ) 5 Br ] SO 4

(i) [ Co ( NH 3 ) 6 ] [ Cr ( CN ) 6 ] and [ Cr ( NH 3 ) 6 ] [ Co ( CN ) 6 ] The isomerism that arises from the interchange of ligands between cationic and anionic, like NH 3 and CN - ligands bound interchangeably to Cr 3 + and Co 3 + respectively, is known as coordination isomerism. (ii) [ Co ( NH 3 ) 5 SO 4 ] Br and [ Co ( NH 3 ) 5 Br ] SO 4 The isomerism that arises when the counter ion in a complex salt is itself a potential ligand and can displace a ligand which can then become the counter ion, is known as ionisation isomerism.

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Which of the following is not a complex compound?

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