Copper(I) Vinylacetylene π-Complexes: Template Synthesis and Structure of the [Cu25Cl17(CC-CH=CH2)8] • 14H2O and [Cu7Cl7(HCC-CH=CH2)3] Compounds

Crystals of the [Cu(25)Cl(17)(C C-CH = CH(2))(8)] center dot 14H(2)O and [Cu(7)Cl(7)(HC C-CH = CH(2))(3)] (II) complexes were obtained by ac electrochemical template synthesis from CuCl(2) center dot 2H(2)O and propargyl alcohol [a DARCh diffractometer, lambda MoK(alpha) radiation, theta/2 theta scan, 388 and 463 independent reflections with F >= 4 sigma(F), R = 0.067 and 0.042 for I and II, respectively]. The crystals of I are tetragonal, a = 19.579(4), c = 25.928(6) angstrom, space group I4(1)/amd, Z = 4. The crystals of II are hexagonal, a = 13.444(4), c = 6.219(1) angstrom, space group P6(3), Z = 2. In these structures, only the C C bond of vinylacetylene is coordinated to the Cu(I) atoms. The ethynyl group of the (-)C C-CH = CH(2) anion in I functions as a doubly bridging pi,sigma-ligand and is bound simultaneously to four copper(I) atoms: two metal atoms are pi-coordinated by the acetylene group, while the two other form the Cu-C bonds of the acetylide type. By contrast, the C C bond of the HC C-CH = CH(2) molecule in II functions only as a bridging pi-ligand and is bound simultaneously to two copper(I) atoms.