Nitridomolybdenum Complexes of Tris(3,5-dimethylpyrazol-1-yl)Hydroborate and the X-Ray Crystal-Structure of {HB(3,5-Me2C3N2H)3)MoN(N3)2

Abstract

The reaction of (NEt4)2[MoNCl5] and K{HB(Me2pz)3}[HB(Me2pz)3- = tris (3,5- dimethylpyrazol-1-yl) hydroborate anion] produces both purple, diamagnetic {HB(Me2pz)3}MoNCl2 (1) and yellow, paramagnetic Net4 [{HB(Me2pz)3}MoNCl2] (2) (e.s.r.: {g} 1.961, {a}(95Mo) 57×10-4 cm-1), which have been separately isolated under different conditions. In contrast, the reaction of [ MoN (N3)4]- with Na{HB(Me2pz)3} results in the exclusive formation of red {HB(Me2pz)3} MoN (N3)2 (3). Crystals of (3) are monoclinic and belong to space group P21/n with a 16.440(2), b 8.787(2), c 16.754(2) ?,ß 112.47(1)°, V 2236.4 ?3, and Z 4. The structure was solved by Patterson and Fourier methods, followed by least-squares refinement, using 3208 reflections, to a conventional R value of 0.032 ( Rw 0.047). In the distorted octahedral complex the molybdenum(VI) atom is coordinated by a facial HB(Me2pz)3- ligand , a terminal nitrido ligand with a Mo-N bond distance of 1.646(4)?, and two azide ligands. All complexes have been characterized by elemental analysis, infrared, 1H n.m.r. or e.s.r. spectroscopy, and mass spectrometry. Improved syntheses for the starting materials (NEt4)2 [MoNCl5] and (NEt4)2 [MoNCl4] are also reported.