Carbonylation of a Tetrameric Aryloxocopper(I) Cluster

Carbonylation of 2,6-diphenylphenoxocopper(I), tetrameric [(CuOC(6)H(3)Ph(2))(4)] (1, Ph = C(6)H(5)), has been shown to result in a [{Cu(OC(6)H(3)Ph(2))(CO)}(2)] dimer (2). The parent aryl oxide, [(CuOC(6)H(3)Ph(2))(4)], which has been prepared from mesitylcopper(I) and 2,6-diphenylphenol, has an approximately planar Cu(4)O(4) core, in which copper(I) is two-coordinated and Cu-O bonds range from 1.834(7) to 1.865(7) Å. Its carbonylation product 2 is a &mgr;(2)-phenoxo-bridged dimer, containing three-coordinated copper(I), with longer Cu-O bonds, viz. 1.953(7)-1.995(7) Å. Cu-C bond lengths in [{Cu(OC(6)H(3)Ph(2))(CO)}(2)] are 1.78(1) and 1.79(1) Å, respectively, with both carbonyl C-O distances equal to 1.12(1) Å, and Cu-C-O angles of 174(1) and 179(1) degrees, respectively. Carbonyl stretching frequencies in the infrared are 2099, 2103, and 2112 cm(-)(1) for the solid and 2102 cm(-)(1) in toluene solution, and the (13)C NMR signal (toluene solution) is at 168 ppm. From comparison with other carbonyl complexes of copper(I), the Cu-C bond is judged to be predominantly of sigma character, with minimal metal --> ligand pi contribution. Both [(CuOC(6)H(3)Ph(2))(4)] and [{Cu(OC(6)H(3)Ph(2))(CO)}(2)] retain their aggregation states on dissolution in nonpolar solvents, as ascertained by cryoscopic molecular weight determinations of the compounds in benzene. Crystal data: 1, triclinic, space group P&onemacr; (No. 2), a = 12.738(9), b = 22.426(5), and c = 9.984(3) Å, alpha = 101.62(2), beta = 91.02(4), and gamma = 85.93(3) degrees, Z = 2, R = 0.052 (R(w) = 0.058) for 721 parameters and 3843 reflections; 2, triclinic, space group P&onemacr; (No. 2), a = 10.67(3), b = 15.72(1), and c = 10.05(1) Å, alpha = 96.99(8), beta = 104.66(16), and gamma = 101.46(12) degrees, Z = 2, R = 0.049 (R(w) = 0.054) for 397 parameters and 2152 reflections.