ORGANOMETALLIC POLYMERS WITH GOLD(I) CENTERS BRIDGED BY DIPHOSPHINES AND DIACETYLIDES

The new ligand, 4,4'-i-Pr2PC6H4C6H4P-i-Pr2 and new digold(I) diacetylides [(AuC=CArC=CAu)x], Ar = 1,4-C6H4,4,4'-C6H4-C6H4,1,4-C6H2-2,5-Me2, have been synthesized. Model digold diacetylides were prepared in the following ways: reaction of [ClAu(mu-PP)AuCl], PP = 4,4'-i-Pr2PC6H4C6H4P-i-Pr2 or 1,4-Ph2PC6H4PPh2, with phenylacetylene and base or reaction of [(AuC=Ph)x] with PP gave [PhC=CAu(mu-PP)AuC=Ph] while reaction of [(AuC=CArC=CAu)x] with PMe3 gave [Me3PAuC=C-Ar-C=CAuPMe3]. The structure of [PhC=CAu(mu-PP)AuC=CPh], PP = 4,4'-i-Pr2PC6H4C6H4P-i-Pr2, was determined by single crystal X-ray diffraction [monoclinic, P2(1)/n, a = 14.378(2) angstrom, b = 13.307(3) angstrom, c = 9.997(1) angstrom, beta = 103.17(1)-degrees, V = 1862.5 angstrom3, Z = 2, R = 0.0354, R(w) = 0.0333] and shown to adopt a conformation with (phenylethynyl)gold(I) units mutually anti. Polymers were prepared in ways similar to those of the model compounds. Thus, polymers [(C=CArC=C-Au-PP-Au-)x], were prepared by reaction of [(AuC=CArC=CAu)x] with diphosphines, PP, or by reaction of [ClAu-(mu-PP)AuCl] with HC=C-Ar-C=CH and base. The latter synthetic method gave polymers with AuCl end groups when PP = 4,4'-i-Pr2PC6H4C6H4P-i-Pr2 but only the derivatives [ClAu-(mu-PP)AuC=C-Ar-C=CAu(mu-PP)AuCl] when PP = 1,4-Ph2PC6H4PPh2, the difference being attributed to the lower solubility of the phenylphosphine derivative. This work shows that kinked, linear polymers can be prepared successfully with diphosphine bridging ligands and that soluble polymers can be prepared if bulky alkyl substituents on phosphorus are present.