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

The new ligand, 4,4'-i-Pr2PC6H4C6H4P-i-Pr2 and new digold(I) diacetyli des [(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-Pr2PC6H4C6H 4P-i-Pr2 or 1,4-Ph2PC6H4PPh2, with phenylacetylene and base or reactio n 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 struct ure of [PhC=CAu(mu-PP)AuC=CPh], PP = 4,4'-i-Pr2PC6H4C6H4P-i-Pr2, was d etermined 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, b eta = 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 thos e 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 b y reaction of [ClAu-(mu-PP)AuCl] with HC=C-Ar-C=CH and base. The latte r 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 attri buted to the lower solubility of the phenylphosphine derivative. This work shows that kinked, linear polymers can be prepared successfully w ith diphosphine bridging ligands and that soluble polymers can be prep ared if bulky alkyl substituents on phosphorus are present.