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

The reaction of (NEt4)2 [M0NCl5] and K(HB(Me2pz)3) [HB(Me2Pz)3_ - tris(3, 5-dimethylpyrazol- l-yl)hydroborate anion] produces both purple, diamagnetic (HB(Me2Pz)3)MoNCl2 (1) and yellow, paramagnetic NEt4 [(HB(Me2Pz)3)MoNCl2l (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)3ÎMoN(N3)2 (3). Crystals of (3) are monoclinic and belong to space group P2\/n with a 16 · 440(2), b 8 · 787(2), c 16 · 754(2) Â, 0 112 · 47(1)°, V 2236 ·4 Å3, 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) Â, 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 [M0NCl5] and (NEt4)2 [M0NCl4] are also reported. © 1990 ASEG.