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Linear and Nonlinear Two-Coordinate Vanadium Complexes: Synthesis, Characterization, and Magnetic Properties of V(II) Amides

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posted on 24.07.2013, 00:00 authored by Jessica N. Boynton, Jing-Dong Guo, James C. Fettinger, Christopher E. Melton, Shigeru Nagase, Philip P. Power
The synthesis and characterization of the first stable two-coordinate vanadium complexes are described. The vanadium­(II) primary amido derivative V­{N­(H)­AriPr6}2 [AriPr6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2] (1) was synthesized via the reaction of LiN­(H)­AriPr6 with the V­(III) complex VCl3·2NMe3 or the V­(II) salt [V2Cl3(THF)6]+I in a 2:1 and 4:1 stoichiometry, respectively. Reaction of the less crowded LiN­(H)­ArMe6 with [V2Cl3(THF)6]+I afforded V­{N­(H)­ArMe6}2 [ArMe6 = C6H3-2,6-(C6H2-2,4,6-Me3)2] (2), which has a nonlinear [N–V–N = 123.47(9)°] vanadium coordination. Magnetometry studies showed that V­{N­(H)­AriPr6}2 and V­{N­(H)­ArMe6}2 have ambient temperature magnetic moments of 3.41 and 2.77 μB, respectively, which are consistent with a high-spin d3 electron configuration. These values suggest a significant spin orbital angular momentum contribution that leads to a magnetic moment that is lower than their spin-only value of 3.87 μB. DFT calculations showed that the major absorptions in their UV–vis spectra were due to ligand to metal charge transfer transitions. Exposure of the reaction mixture for 2 to dry O2 resulted in the formation of the diamagnetic V­(V) oxocluster [V­{N­(H)­ArMe6}2]2(μ-O–Li–O)2 (3).