Copper(I) pi-complexes with acetylene ligands. Synthesis and crystal structure of the copper(I) chloride pi-complex with propargyl alcohol: 2CuCl center dot HC CCH2OH

Crystals of the 2CuCl . HC=CCH2OH complex were prepared by the direct react ion of CuCl with propargyl alcohol in a hydrochloric solution and studied b y X-ray diffraction analysis [a DARCh automated diffractometer, lambda MoKa lpha, theta/2 theta scan mode, 1965 independent reflections with F greater than or equal to 4 sigma(F), R = 5.0%]. The crystals are monoclinic, a = 20 .059(5), b = 15.187(5), c = 6.196(2) Angstrom, gamma = 101.81(2)degrees, sp ace group P2(1)/a, Z = 12. The C=C bond of the HC=CCH2OH molecule functions as a bridging pi-ligand in the structure and is bound simultaneously to tw o copper(I) atoms. The =C-H ... Cl hydrogen bonds [H ... Cl 2.6-2.9(1) Angs trom] and contacts of the R-OH ... O(H)R type [H ... O 1.8, 2.1(1) Angstrom ] stabilize the structure.