Synthesis and Coordination Chemistry of the Bis(imidazole) Ligand, Bis(1-methyl-4,5-diphenylimidaz-2-oyl)(benzyloxy)methane

The synthesis and characterization of the new imidazole
ligand
bis(1-methyl-4,5-diphenylimidaz-2-oyl)(benzyloxy)methane (BimOBz) and its copper(II) complexes
[Cu(BimOBz)2][BF4]2·2H2O
(1·2H2O),
[Cu(BimOBz)(NO3)2]·CH2Cl2 (2·CH2Cl2) and
[Cu(BimOBz)Cl2]·2EtOH
(3·2EtOH) are presented. The X-ray
crystallographic parameters
determined are as follows:  1·solv (solv =
petroleum ether)
C84H66N8B2CuF8O2,
1456.65, monoclinic space group
(P21/a), a =
20.862(8) Å, b = 19.110(5) Å, c =
22.452(9) Å, β = 110.09(3)°, Z = 4,
R = 0.129, and Rw =
0.139. 2·CH2Cl2,
C41H36N6Cl2O7,
859.22, monoclinic space group
(P21/c), a =
9.748(1) Å, b = 14.157(5) Å,
c
= 17.209(2) Å, β = 103.709(8)°, Z = 4,
R = 0.066, and Rw = 0.087.
3·2EtOH,
C44H38N4Cl2CuO2,
789.26,
monoclinic space group (P21/a),
a = 17.171(5) Å, b = 13.988(3) Å,
c = 17.897(5) Å, β = 112.52(2)°,
Z = 4,
R = 0.084, and Rw = 0.092.
The geometry at these CuII centers is distorted
tetrahedral in 1 and 3 and
essentially
square-planar in 2, and this difference is reflected in
their EPR spectra, especially the value of
Az; 1 (solid,
gx =
2.06, gy = 2.13,
gz = 2.30,
Az = 94 ×
10-4 cm-1),
3 (CH2Cl2, 77 K,
gx =
gy = 2.06,
gz = 2.37,
Az = 75 ×
10-4
cm-1), 2 (solid,
gx =
gy = 2.06,
gz = 2.28,
Az = 169 ×
10-4 cm-1).
1 displays a reversible, one-electron
CuII/CuI
couple in CH2Cl2 and MeCN at potentials of
+0.62 and +0.49 V vs SCE, respectively.