NOVEL TRINUCLEAR AND HEXANUCLEAR HETEROORGANOCOPPER COMPOUNDS WITH PHOSPHINE-LIGANDS, BRIDGING ALKYNYLS, AND INTRAMOLECULARLY COORDINATING BRIDGING ARENETHIOLATES - X-RAY STRUCTURES OF [CU3(SC6H4(CH(R)NME2)-2)2(C-EQUIVALENT-TO-C-T-BU)]2 (R = H, ME)

(Arenethiolato)alkynylcopper(I) complexes [Cu3{SC6H4(CH(R)NMe2)-212(C=C-t-Bu)]2 (R = H, Me) with an intramolecularly coordinating ligand have been prepared from the reaction of [CuSC6H4(CH(R)NMe2)-2]3 with either CuC=C-t-Bu or LiC=c-t-Bu. Crystals Of [CU3{SC6H (CH2NMe2)-2}2(C=C-t-Bu)]2 (3) are monoclinic with a = 11.213 (1) angstrom, b = 18.360 (2) angstrom, c = 13.118 (1) angstrom, beta = 103.72 (1)-degrees, space group P2(1)/c, Z = 2, and R = 0.061 for 1956 reflections with I greater-than-or-equal-to 3sigma(I) and 305 variables. Crystals of [Cu3{SC6H4-((R)-CH(Me)NMe2)-212(C=C-t-Bu)]2 (4) are monoclinic with a = 11.600 (2) angstrom, b = 17.071 (3) angstrom, c = 15.513 (3) angstrom, beta = 101.53 (1)-degrees, space group P2(1), Z = 2, and R = 0.056 for 5573 reflections with I greater-than-or-equal-to 2.5sigma(I) and 647 variables. Each structure contains two Cu3{SC6H4(CH(R)NMe2)-212(C=C-t-Bu) units that have Cu3S2C six-membered rings in a boatlike conformation with alternating copper and sulfur or carbon atoms. Through side-on coordination of the bridging alkynyl group of one unit to a coordinatively unsaturated copper atom of a second unit a hexanuclear structure is formed. This is the first example of a symmetrical (mu3-C(alpha), mu1-C(beta))-eta2 bridging alkynyl group. In the crystal structures the orientation of the ligands affords two conformers of the Cu3{SC6H4(CH(R)NMe2)-212(C=C-t-Bu) units; in solution H-1 NMR provides evidence for three conformations which are in equilibrium with a low free activation energy barrier. Furthermore, there is an equilibrium between the hexanuclear structure and two trinuclear units. Hexanuclear 3 and 4 react with phosphine ligands (L) to form the trinuclear heteroorganocopper species [CU31SC6H4(CH(R)-NMe2)-2}2(C=C-t-Bu)(L)]. Our results show that in addition to anionic species neutral Cu3(SAr)2(C=C-t-Bu) species that have a reactive site with specific Lewis acidic properties can also be present in cuprate reagent mixtures.