Formation study and X-ray structures of dinuclear beta-diketonate copper(I) complexes with conjugated ene-yne Lewis base. Implications for the use of(hfac)Cu(MHY) as a precursor for copper CVD

Dinuclear [(hfac)Cu](2)(MHY) and [(hfac)Cu](2)(HY) species, where hfac = he xafluoroacetylacetonate, MHY = 2-methyl-1-hexen-3-yne, and HY = hex-3-yn-1- ene), are formed during copper chemical vapor deposition experiments when a bubbler containing the corresponding mononuclear species is used. These co mpounds and the so far unknown (hfac)Cu(HY) have been characterized by H-1 and C-13 NMR and IR spectroscopy and the two dinuclear species by X-ray cry stallography and elemental analysis. As expected, in the structure of the d inuclear species, two roughly perpendicular Cu(hfac) moieties are bound to a single ene-yne: one to the C-C triple bond, the other to the conjuguated double bond. Weak intra- and intermolecular Cu . . . Cu interactions have b een detected in the solid. [(hfac)Cu](2)(HY) is more stable and more easily formed than [(hfac)Cu](2)(MHY) because of the hindrance character of the a dditional methyl groups. The formation of the dinuclear species from the mo nonuclear species is reversible as it has been demonstrated by 1H NMR. The mononuclear species can be recovered from the dinuclear species when,free e ne-yne base is added. Crystallographic data for [(hfac)Cu](2)-MHY): C17H12O 4F12Cu2, triclinic, P (1) over bar (No. 2), Z = 4; at 298 K, a = 11.112(3) Angstrom, b = 13.472(4) Angstrom, c = 15.747(3) Angstrom, alpha = 94.95(2)d egrees, beta = 98.15(2)degrees, gamma = 100.27(2)degrees; Crystallographic data for [(hfac)Cu](2)(HY): C16H10O4F12Cu2, orthorhombic, Cc2a (No. 41, Aba 2), Z = 8; at 230 K, a = 12.280(3) Angstrom, b = 13.531(3) Angstrom, c = 25 .461(5) Angstrom.