Azidokomplexe von Vanadium(IV) und Vanadium(V): (Ph4P)2[VOCl2(μ-N3)]2 und (Ph4P)2[VOCl(μ-N3)(N3)2]2†
Professor Heinrich Nöth zum 80. Geburtstag gewidmet
Abstract
Azido Complexes of Vanadium(IV) and Vanadium(V): (Ph4P)2[VOCl2(μ-N3)]2 and (Ph4P)2[VOCl(μ-N3)(N3)2]2
(Ph4P)2[VOCl2(μ-N3)]2 (1) was prepared by reaction of (Ph4P)[VO2Cl2] with trimethylsilylazide in the molar ratio 1:2 in dichloromethane solution to give dark green, moisture sensitive, non-explosive single crystals. The reaction is accompanied by the formation of the dark blue side-product (Ph4P)2[VOCl(μ-N3)(N3)2]2 (2a), which can be obtained as the main product by application of a large excess of Me3SiN3. Dark blue needles of 2a crystallize spontaneously from the CH2Cl2 solution within one hour at 4 °C. After standing at 4 °C under its mother liquid within 24 hours a first-order phase transition of 2a occurs forming dark blue prismatic single crystals of 2b. According to single crystal X-ray structure determinations, 2a and 2b crystallize in the same type of space group 
, however, with different lattice dimensions.
The vanadium(IV) complex 1 is characterized by X-ray structure determination and by vibrational spectroscopy (IR, Raman) as well as by EPR spectroscopy, whereas 2b is characterized by IR spectroscopy.
1: Space group P21/n, Z = 2, a = 1009.5(1), b = 1226.6(2), c = 1943.0(2) pm, β = 98.42(1)°, R1 = 0.0672. The complex anion 
forms centrosymmetric units with V2N2-four-membered rings with a V···V distance of 335.6(1) pm and coordination number five on the vanadium(IV) atoms.
2a: Space group 
, Z = 1, a = 1089.0(2), b = 1097.1(2), c = 1310.1(2) pm, α = 92.99(1)°, β = 106.12(2)°, γ = 117.05(2)°, V = 1309.8(4) Å3, dcalc. = 1.440 g·cm−3, R1 = 0.0384. The complex anion forms centrosymmetric units of symmetry Ci with V2N2 four-membered rings and VN bond lengths of 200.4(3) and 234.4(2) pm, respectively. The non-bonding V···V distance amounts to 356.2(1) pm.
2b: Space group 
, Z = 1, a = 1037.3(2), b = 1157.6(2), c = 1177.2(2) pm, α = 98.48(2)°, ° = 103.82(2)°, γ = 106.33(2)°, V = 1281.8(4) Å3, dcalc. = 1.471 g·cm−3, R1 = 0.0724. The structure of the complex anion 
is similar to the anion of 2a with VN bond lengths of the four-membered V2N2 ring of 203.3(4) and 235.2(4) pm, respectively, and a non-bonding V···V distance of 357.5(1) pm.
