The stable colourless crystalline complex, (Et,P),Pd(H)CI is obtained by the reduction of (Et,P),PdCI, with trimethylgermane at 40". Reduction of (Et,P),PdBr, is slow unless palladium black is added. The analogous reaction with (Et,P),NiBr, gives a highly unstable nickel hydride complex. The reactions are considered to follow a radical chain mechanism.The reactions of (Et,P),Pd(H)CI with the following are reported : KI, HCI-Et,O, NH,-H,O, CCI,, MeSH-KCN, and MeOH-KCN. Unsaturated compounds (CH,:CHCN, PhCiCH, C, F, , C, H, ) also react with it to give a complexity of products.OF the metals, nickel, palladium, and platinum only the latter has been shown t o form a well defined series of hydrido-complexes. These are mostly uninuclear compounds of the type trans-L,Pt (H)X, although two cisuninuclear complexes have been described, cis- (P h,PCH2) ,Pt (H) GePh, and cis-(Ph,P) ,P t (H) C1 .l Preparative methods usually involve the reduction of a bis(tertiary phosphine)platinum dihalide by use of reagents which result in either a strongly basic environment (EtOH + KOH, LiAlH,, N,H,) or an acidic medium (H, which gives HX, HCO,H)., The reason why these methods are unsatisfactory for palladium analogues is that hydridopalladium complexes decompose rapidly in acidic or basic media. " Neutral " reducing agents, which have been applied to the formation of platinum h y d r i d e ~, ~-~ are illustrated in reactions (1)-(3); these reactions are believed to proceed through octahedral plat iniim intermediates.