coordination compound 4

Question 1

CFT

Answer 1

The crystal field theory (CFT) is an electrostatic model which considers
the metal-ligand bond to be ionic arising purely from electrostatic
interactions between the metal ion and the ligand. Ligands are treated
as point charges in case of anions or point dipoles in case of neutral
molecules.

Question 2

degeneracy is
maintained if

Answer 2

This degeneracy is
maintained if a spherically symmetrical field of negative charges
surrounds the metal atom/ion.

Question 3

when this negative field is
due to ligands

Answer 3

However, when this negative field is
due to ligands (either anions or the negative ends of dipolar molecules
like NH3
and H2
O) in a complex, it becomes asymmetrical and the
degeneracy of the d orbitals is lifted. It results in splitting of the d
orbitals. The pattern of splitting depends upon the nature of the crystal
field.

Question 4

CFSE

Answer 4

splitting of the degenerate levels due to the
presence of ligands in a
definite geometry is termed as
crystal field splitting and
the energy separation is
denoted by deltao

Question 5

The crystal field splitting,
deltao
, depends upon the

Answer 5

The crystal field splitting,
deltao
, depends upon the field
produced by the ligand and
charge on the metal ion.

Question 6

spectrochemical series

Answer 6

It is an
experimentally determined series based on the absorption of light
by complexes with different ligands.

Question 7

if
cfse<p

Answer 7

t2g 3 eg 1

Question 8

if cfse>p

Answer 8

t2g 4 eg0

Question 9

why g in eg not there for tetrahedral

Answer 9

Since
tetrahedral complexes lack symmetry, ‘g’
subscript is not used with energy levels.

Question 10

why no colour when no ligand?

Answer 10

in the absence of ligand,
crystal field splitting does
not occur and hence the
substance is colourless.

Question 11

The crystal field model is successful in explaining

Answer 11

The crystal field model is successful in explaining the formation,
structures, colour and magnetic properties of coordination compounds
to a large extent.

Question 12

Limitations
of Crystal
Field
Theory

Answer 12

• from the assumptions that the ligands are
  point charges, it follows that anionic ligands should exert the greatest
  splitting effect. The anionic ligands actually are found at the low end
  of the spectrochemical series.
• Further, it does not take into account
  the covalent character of bonding between the ligand and the central
  atom.
• These are some of the weaknesses of CFT, which are explained
  by ligand field theory (LFT) and molecular orbital theory which are
  beyond the scope of the present study.

Question 13

why OS of metal in CO is 0?

Answer 13

• The metal-carbon bond in metal carbonyls
  possess both and character.
• The M–C bond
  is formed by the donation of lone pair of electrons
  on the carbonyl carbon into a vacant orbital of
  the metal.
• The M–C
  bond is formed by the
  donation of a pair of electrons from a filled d orbital
  of metal into the vacant antibonding * orbital of
  carbon monoxide.
• The metal to ligand bonding
  creates a synergic effect which strengthens the
  bond between CO and the metal