Tris (4-bromo-1H-pyraaol-1-yl)borato derivatives of first-row transition and group 12 and 14 metals. X-ray crystal structure of [HB(4Brpz)(3)](2)Cd. Cd-113 solution NMR study of bis[poly(pyrazolyl)borato] cadmium complexes

A series of metal complexes M[HB(4-Brpz)(3)](2) [HB(4-Brpz)(3) = hydridotris(4-bromo-1H-pyrazol-1-yl)borate and M = Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb] were obtained from reaction of K[HB(4-Brpz)(3)] and the appropriate metal salt in aqueous solution. These air-stable complexes are sparingly soluble in most common solvents; they have been investigated through elemental analysis, conductivity measurements, IR, UV-vis and, in the case of diamagnetic compounds, H-1 and C-13 NMR spectroscopy. The X-ray crystal structure of cadmium(II)bis[hydridotris(4-bromo-1H-pyrazol-1-yl)borate] has been resolved. Six-coordinate cadmium is present in a slightly distorted octahedron with the axes not linear [angles 176.8(3), 177.2(3) and 178.7(3)degrees]. The 'bite' of the ligand, i.e. N-Cd-N angle, lies in the range 81.6(2)-84.1(3)degrees (weighted average 82.4(4)degrees). The Cd-N distances vary from 2.298(8) to 2.329(8) Angstrom (weighted average 2.317(5) Angstrom). The geometry around the B atom is tetrahedral. The N-B-N angles range from 105.8(8) to 110.5(7)degrees (weighted average 108.5(7)degrees); the B-N bond distances vary from 1.53(2) to 1.62(1) Angstrom (weighted average 1.58(1) Angstrom). We report and discuss also the Cd-113 NMR solution data of several cadmium poly(pyrazol-1-yl)borates). (C) 1997 Elsevier Science Ltd.