Copper(I) acetylenide complexes. Synthesis and structure of cluster pi compound (AnH)(2)[Cu4Cl5(C CCH2OH)] (AnH(+) equals anilinium cation)

Crystals of the cluster pi compound (AnH)(2)[Cu4Cl5(C=CCH2OH)] (AnH(+) = an ilinium cation C6H5NH3+) are obtained by ac electrochemical synthesis and s tudied by X-ray structural analysis [DARCH automated diffractometer, lambda MoKalpha, theta/2 theta scan mode; 502 independent reflections with F grea ter than or equal to 4 sigma(F), R = 0.036]. Crystals are orthorhombic: spa ce group P2(1)2(1)2(1), Z = 4, a = 24.204(8), b = 15.488(7), c = 5.759(2) A ngstrom. In the structure of the complex, the C=C bond of the propargyl ani on functions as doubly bridging pi,sigma-ligand. It is simultaneously bonde d to four Cu(I) atoms: two copper atoms are pi-coordinated by the ethynyl g roup, and two other form the Cu-C bonds of acetylenide type. The shortes Cu ... Cu distance in the resulting [Cu-4] cluster is 2.449(8) Angstrom.