1) Provide explanations for the number of intense perchlorate Cl-O stretching vibrational modes observed in the IR of the following three silver(I) complexes.
a) The perchlorate anion in Ag(NH3)2(ClO4) has a single intense Cl-O stretching vibrational mode observed by IR at 1170cm-1.
b) The IR of Ag(NH3)ClO4 has three Cl-O stretching vibrational modes at 1220 cm-1,1130 cm-1and 920 cm-1 observed in the IR .
c) The IR of AgClO4 has four Cl-O stretching vibrational modes at 1210 cm-1,1140 cm-1 , 1040 and 910 cm-1 observed in the IR .
2) The gas phase cobalt(II) free ion has a 4F ground term which in an octahedral ligand field splits into 4T1g (-0.6 Δo – CI) , 4T2g(+0 .2 Δo) and 4A2g (+1,2 Δo ) electronic states.
a) How many micro states are contained in the 4F ground term of gas phase cobalt(II) free ion and the4T2g electronic state for an octahedral cobalt(II) complex ?
b) What is the ground state for a tetrahedral cobalt(II) complex ?
c) Provide an explanation for the difference in effective magnetic moments between K2[CoCl4] (μeff(298K) = 3.9 β) and K4[CoCl6] (μeff (298K)= 5.0β) . (β = electron Bohr Magneton)
d) What are the Δo and CI values for an octahedral Co(II) complex that has ligand field transitions at Δν1 =7,400cm-1 (4T2g ←4T1g) and Δν2 =15,400cm-1 (4A2g ←4T1g) ?
3 Vanadium tetrachloride (VCl4 ) is a bright red colored liquid with a vapor pressure of 5×10-2 torr at 298K.
a) Briefly discuss why the standard state of VCl4 is a liquid and VCl2 is an ionic solid?
b) How many microstates are in the gas phase V4+ free ion ground term and the V4+ free ion ground J state ?
c) How many microstates are present in the ground electron configuration and ground electronic state for VCl4 assuming tetrahedral symmetry ?
d) State the Jahn Teller Theorem and briefly discuss whether or not VCl4(g) is expected to manifest a Jahn Teller effect .
e) What is the expected orbital angular momentum in the ground
state of VCl4(g) ?
f) The molar magnetic susceptibility (χm) at 298K is +1130×10-6 cm3mol-1 .
What is the effective magnetic moment for VCl4 at 298K and does this μeff fulfill the expectations for VCl4 ground state in Td symmetry ?
g) Use the electric dipole transition selection rules to show whether or not the ligand field ( d→d ) transition(s) for VCl4 are spin and orbitally allowed as pure electric dipole transitions assuming Td symmetry.
h) Write down the irreducible representations for VCl4(g) translations , rotations and vibrations assuming Td symmetry.
