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DEPARTMENT OF CHEMISTRY
CH 102 (INORGANIC): TUTORIAL NO.3
(www.chem.iitb.ac.in/~rmv/ch102/tutorial3.htm)
(Answers on the Web on Feb 08, 2002)
1. Crystalline AgO is diamagnetic. Explain.
Half of the silver atoms in AgO are linearly coordinated to two nearest neighbor
oxygen atoms and half are coordinated to four nearest neighbor oxygen atoms in a
square planar configuration.
i.e. the silver ions exist in a mixture of oxidation states viz. Ag+ and Ag3+.
Ag+, linear coordination, sp hybridization, d10
Ag3+, square-planar coordination, dsp2 hybridization, d8
2. Draw structures of the following complexes using the valence bond approach:
(a) Ni(CO)4,
(b) [Ni(CN)4]2(c) (CoCl4)2(d) OsO4
(e) VOCl3
2+
+
2(f) [Pt(NH3)4]
(g) [Ag(NH3)2] , (h) [Pt(PPh3)4] (i) (Cr2O7)
(a) Ni(CO)4,
(b) [Ni(CN)4]2(c) (CoCl4)2(d) OsO4
(e) VOCl3
(f) [Pt(NH3)4]2+
(g) [Ag(NH3)2]+
(h) [Pt(PPh3)4]
(i) (Cr2O7)2-
d10
d8
d7
d0
d0
d8
d10
d10
d0
Ni(0)
Ni(II)
Co(II)
Os(VIII)
V(V)
Pt(II)
Ag(I)
Pt(0)
Cr(VI)
sp3
dsp2
sp3
d3s
d3s
dsp2
sp
sp3
d3s
Td
sq. planar
Td
Td
Td
sq. planar
linear
Td
Td
3. Draw all possible isomers of (a) octahedral [RuCl2(NH3)4], (b) square planner
[IrH(CO)(PR3)2] (c) Octahedral [IrCl3(PEt3)3], (d) [Ru(bipy)3]2+
(a)
Cl
Cl
NH3
Cl
Ru
NH3
NH3
NH3
H3N
Ru
NH3
H3N
Cl
NH3
Trans
Cis
H
Co
R3P
H
(b)
Ir
Ir
PR3
R3 P
cis
PR3
OC
trans
(c)
Cl
Cl
Cl
Et3P
Ir
Et3P
PEt3
Ir
Cl
PEt3
Cl
PEt3
Meridonial
Facial
(d)
Cl
PEt3
bipy
bipy
Ru
bipy
Ru
bipy
bipy
bipy
d-isomer
l-isomer
4. Give formula for (a) pentaamminechlorocobalt(III)chloride,
(b) [µ-hydroxobis(pentaamminechromium(III)]chloride
[{Cr (NH3)5}2(µ-OH)]Cl5
(a) [CoCl(NH3)5]Cl2 (b)
5+
H3N
NH3
H
O
Cr
H3N
H3N
NH 3
H3N
Cr
NH3
H3N
NH3
NH3
5. Which electron configuration of a d5 transition metal complex, the high-spin or low spin
configuration, would you expect to be favored by the application of high pressure and
why?
Low spin; because it leads to low electron density between the metal and
ligands (i.e. along the bond axis)
6. Suggest a reason for the fact that a number of tetrahedral Co(II) complexes are stable,
whereas the corresponding Ni(II) complexes are not.
The CFSE of a d7 Td complex is greater than that of d8 Td complex.
Similarly, the CFSE of a d8 Oh complex is greater than that of a d7 Oh complex.
7. Using crystal field stabilization energy as the criterion, indicate whether you expect the
following spinels to be normal or inverse: Fe3O4, Co3O4 .
By definition, the 3+ ion has to go to Oh site leaving the 2+ ion in Td.
Fe3O4 is [composed of Fe(II) Td and Fe(III) Oh ions with d6 and d5 configuration,
respectively. Since d5 has no CFSE, it is more advantageous to put it in a Td
environment than Oh. In other words, by placing d6 ions in Oh environment there
more gain in CFSE than keeping this in Td environment. Hence the structure is
INVERSE.
Co3O4 has a similar structure with d7 and d6 configurations for 2+ and 3+ ions,
respectively. Co3+ d6 ion is low spin because of its (a) high charge (even with
weak ligands like oxo) and (b) maximum gain in CFSE. So the structure is
NORMAL.
8. Determine configuration (in terms of t2g m eg n or e m t2 n), the no of unpaired electrons, and
the CFSE (in terms of ∆o or ∆t) for each of the following complexes.
(a) tetrahedral (FeCl4)2-;
(b) W(CO)6
(a) e3t23
(b) t2g6eg0