Complexes of heteroscorpionate trispyrazolylborate anionic ligands Part II. The X-ray crystallographic and H-1 NMR studies on thiocyanato[hydrobis(3-phenylpyrazolyl)(3,5-di-tert-butylpyrazolyl)borato]cobalt(II) and thiocyanato[hydrobis(3-phenyl,5-methylpyrazolyl)(3-methyl,5-phenylylpyrazolyl)borato]cobalt(II) complexes

Synthesis of two heteroscorpionate tris(pyrazolyl)borate anionic ligands (T p') was described; the sterically demanding [hydro-bis(3-phenylpyrazolyl)(3 ,5-di-tert-butyl obtained by condensation of KBH4 with 3-phenylpyrazole and 3,5-di-tert-butylpyrazole and [hydrpbis(3-phenyl,5-methlpyrazolyl)(3-methy l, 5-phenylylpyrazolyl)borate](-) and [hydrobis(3-phenyl,5-methylpyrazolyl) (3- 5-phenylylpyrazolyl)borate] - formed in similar reaction between NaBH4 and 3(5)-methyl,5(3)-phenylpyrazole. The ligands were converted into tetrac oordinate [HB(3,5-di-tBupz)(3-Phpz)(2)]Co(NCS) and pentacoordinate [HB(3-Me ,5-Phpz)(3-Ph, 5-Mepz)(2)]Co(NCS)(THF) THF complexes, which molecular struc tures were determined by X-ray crystallographic method. The reactivity of h igh-spin cobalt(II) complexes was studied by the 'H NMR spectroscopy in sol ution. The reactive [HB(3-Me,5-Phpz)(3-Ph.5-Mepz)(2)]Co(NCS) complex readil y underwent conversions into pentacoordinate [HB(3-Me,5-Phpz)(3-Ph,5-Mepz)( 2)]Co(OOCCH(OH-OH(3))and hexacoordinate [HB(3-Me,5-Phpz)(3-Ph,5-Mepz)(2)]Co [HB(pz)(3)] complexes. (C) 2001 Elsevier Science B.V. All rights reserved.