NEW ROUTE TO COMPLEXES HAVING SUBSTITUTED QUINOLINE-2-THIOLATE LIGANDS THROUGH THE METAL-ASSISTED COUPLING AND CYCLIZATION OF ARYL ISOTHIOCYANATES TO ALKYNE LIGANDS

Reactions of the lightly stabilized dimetalated olefin complex Re(CO)4[trans-mu-HC=C(CO2Me)]Re(CO)4(NCMe) (1) with p-tolyl isothiocyanate has yielded the complex Re(CO)4[(E)-HC=C(CO2Me)C=N(C6H4-p-Me)S]Re(CO)4 (2; 58% yield) by insertion of the isothiocyanate into the substituted Re-C bond. When 2 is treated with I2 in the presence of UV radiation, the tolyl ring cyclizes with the unsubstituted end of the metalated olefin to yield a new substituted quinoline-2-thiolate ligand in the complex Re2(CO)7[mu-2-S-3-CO2-Me-6-Me-NC9H4](mu-I) (3; 18% yield). Complexes 2 and 3 were characterized by IR, H-1 NMR, and single-crystal X-ray diffraction analyses. Crystal data: for 2, space group P2(1)/c, a = 10.317(1) angstrom, b = 15.819(2) angstrom, c = 15.448(3) angstrom, beta = 103.26(1)degrees, Z = 4, 2415 reflections, R = 0.027; for 3.CH2Cl2, P1BAR, a = 10.204(4) angstrom, b = 13.733(6) angstrom, c = 9.877 (2) angstrom, alpha = 91.18(3)degrees, beta = 96.17(3)degrees, gamma = 74.78(3)degrees, Z = 2, 2746 reflections, R = 0.038.