Alkynylbis(alkylidynyl) phosphines: {L_nM≡C}₂PC≡CR

Sequential treatment of [M(?CBr)(CO)(2)(Tp*)] (M = Mo, W; Tp* = hydrotris(dimethylpyrazolyl)borate) with (BuLi)-Bu-n, RPCl2 and LiC?CSiMe3 affords [M{?CPR(C?CSiMe3)}(CO)(2)(Tp*)] (R = Ph, Cy) which are readily desilylated (TBAF) to provide the parent ethynyl derivatives [M{?CPR(C?CH)}(CO)(2)(Tp*)]. Alternatively, treating [W(?CBr)(CO)(2)(Tp*)] with (BuLi)-Bu-n, 1/2 PCl3 and LiC?CR affords the alkynylbis(alkylidynyl)phosphines [RC?CP{C?W(CO)(2)(Tp*)}(2)] (R = C6H5, C6H4Me-4, CMe3, SiMe3) and again the silyl derivative may be desilylated to the parent (R = H) which is readily converted to an arsino derivative (R = AsPh2). These novel architectures present new linkages for bridge-assisted polymetallic assembly.