the reactions between co(c10[subscript4])[subscript2].6h[subscript2]o or cocl[subscript2].6h[subscript2]o, nabh[subscript3]cn and some monodentate (pph[subscript3] and pcy[subscript3]) and a series of bidentate phosphines of the type ph[subscript2]p-(ch[subscript2])[subscriptn]-pph[subscript2] (n = 1-4) and also cis and trans ph[subscript2]p-(ch[subscript2])[subscriptn]-pph[subscript2] have been studied under a very wide range of experimental conditions. the reactions are affected by (1) the amount of nabh[subscript3]cn used, (2) the rate of addition of nabh[subscript3]cn, (3) the temperature, (4) the solvent used and (5) the reaction time. a number of cyanotrihydroborato and other complexes have been produced and others observed but not yet isolated.