The synthesis of the highly encapsulating pyrazolylborate ligand hydrotris(3-p-cumenyl-5-methylpyrazolyl)borate (L = Tp(Cum,Me)) and of its zinc hydroxide complex L . Zn-OH (1) are described. 1 is converted by H2S into the hydrosulfide complex L . Zn-SH (2). Both 1 and 2 seem to be contaminated with traces of the isomeric species 1’ and 2’ containing L’ with one 3-methyl-5-p-cumenyl substituent. Thermal condensations of 1’ and 2 yield the molecular zinc oxide and sulfide complexes L’. Zn-O-Zn . L’ (3’) and L . Zn-S-Zn . L (4). The hydroxide complex 1 has been found to react readily with cumulated double-bonded species : CO2 is incorporated in alcoholic solutions to form the alkylcarbonate complexes L . Zn-OCOOR (5). Similarly, CS2 in ethanol forms the O-ethyl dithiocarbonate complex L . Zn-SC(S)OEt (6). SO2 is converted to a bridging sulfito ligand in L . Zn-O-SO-O-Zn . L (7), and phenyl isothiocyanate is bound as a thiocarbamidato ligand in L . Zn-SC(O)NHPh (8). Complexes 1, 2, 2’, 3’, 4, 5, and 6 have been confirmed by structure determinations and complexes 7 and 8 by spectral data.