trans[(C6F5)(R3P)2Pt(CC)nPt(PR3)2(C6F5)] With Odd Numbers of Triple Bonds; Avoiding Complicating Ethynediyl Extrusions Synthetic Approaches to and Structures of Diplatinum Polyynediyl Complexes trans

AbstractReactions of trans(C6F5)(ptol3P)2Pt(CC)nSiEt3 (PtC2nSi; n=5, 7, 9) and excess PtCl in the presence of wet nBu4N+ F (to effect protodesilylation) under Sonogashiratype conditions (CuCl, base, other additives) afford the title compounds PtC10Pt, PtC14Pt, and PtC18Pt in 4232% yields. A fourfold substitution of the phosphine ligands in PtC10Pt by PEt3 affords Pt'C10Pt (78%), and a Sonogashira reaction of Pt'C2H and Pt'Cl affords Pt'C2Pt (68%). The analogous reaction with PtC2Si and PtCl is unsuccessful, presumably for steric reasons. The crystal structures of PtC10Pt, PtC14Pt, Pt'C10Pt, and Pt'C2Pt exhibit a number of interesting trends and features. Certain sp chain extension reactions that lead to or employ the precursors PtC10Si, PtC12Si, PtC14Si, and PtC18Si sometimes give byproducts derived from C2 loss, and possible origins are discussed. Related phenomena have been reported by others in the course of synthesizing extended conjugated polyynes.

Synthetic Approaches to and Structures of Diplatinum Polyynediyl Complexes trans,trans[(C6F5)(R3P)2Pt(CC)nPt(PR3)2(C6F5)] With Odd Numbers of Triple Bonds; Avoiding Complicating Ethynediyl Extrusions