REACTIVITY OF MOLYBDENUM COMPLEXES CONTAINING BOTH NHNPHR AND NNPHR LIGANDS (R = PH, ME) TOWARD HYDRIDOTRIS(PYRAZOLYL)BORATE, TP AND HYDRIDOTRIS(3,5-DIMETHYLPYRAZOLYL)BORATE TP-ASTERISK, LIGANDS - X-RAY CRYSTAL-STRUCTURE OF [TPMO(NNMEPH)(2)CL]

Molybdenum complexes containing mixed disubstituted organohydrazido(1- ) and organohydrazido(2-) ligands, [Mo(NHNPhR)(NNPhR)(acac)Cl-2], R = Ph (I), R = Me (II), react in acetonitrile with sodium hydridotris(pyr azolyl)borate, NaTp, or in toluene with potassium hydridotris(3,5-dime thylpyrazolyl)borate, KTp, to afford the neutral six-coordinated spec ies formulated as [TpMo(NNPhR)(2)Cl], R=Ph (III), R=Me (IV) and [TpMo (NNPhR)(2)Cl], R=Ph (V), R=Me (VI). These compounds have been characte rized by elemental analysis, by IR, UV-visible, H-1 and C-13 NMR spect roscopy, and by mass spectrometry. The electrochemical behavior of com plexes III-VI has also been studied by cyclic voltammetry. The X-ray c rystal structure of IV has been determined. Crystals are parallelepipe d, space group Pbnm, with a=7.468(2), b=18.483(3), c=19.052(3) Angstro m, alpha=beta=gamma=90 degrees and Z=4. The structure was solved and r efined by full-matrix, least-squares methods to R and R-w values of 0. 038 and 0.049, respectively. The complex displays a distorted octahedr al geometry with symmetrical organohydrazido(2-) ligands adopting the nearly linear mode (Mo-N-N=169.4(3)degrees). This linearity and the sh ea bond distances (Mo-N=1.771(4), N-N=1.308(5) Angstrom) indicate an e xtensive pi-electronic delocalization throughout the Mo-N-N fragment. (C) 1998 Elsevier Science S.A.