SYNTHESES AND CHARACTERIZATIONS OF AU(2)MNT(PR(3))(2) (R=ME, ET, OPH, CY) - STUDY OF STRUCTURAL FEATURES OF OPEN RING COMPLEXES AS A FUNCTION OF TERTIARY PHOSPHINE AND PHOSPHITE CONE ANGLE

Dinuclear gold(I) ''open ring'' complexes of the type [Au-2(MNT)(PR(3))(2)] (MNT = 1,2-dicyanoethene-1,2-dithiolate-S,S') have been synthesized. The tertiary phosphines and phosphite used include PMe(3), 1, P(OPh)(3), 2, PEt(3), 3, and PCy(3), 4. The molecular structure of these complexes as determined through X-ray crystallography show an MNT unit bridging two gold(I) centers and a trialkylphosphine or triphosphite ligand coordinated to each gold(I) atom. One of the gold centers exhibits a linear two-coordinate geometry while the other gold(I) atom is an irregular three coordinate center in each of these MNT complexes. While remaining unsymmetrical, the steric bulk of the tricyclohexylphosphine prevents a close Au ... Au contact from forming, causing the two gold atoms to be positioned on opposite sides of the ligand plane. Solution P-31{H-1}) NMR for each of these compounds gives only one signal from room temperature to -80 degrees C for these compounds. Au Au contacts are found with the less bulky phosphines which are positioned on the same side of the MNT ligand plane. Pertinent crystal data are as follows: Compound 1 crystallizes in the monoclinic space group P2(1), with a 9.261(2) Angstrom, b = 10.544(3) Angstrom, c = 10.007(4) Angstrom, beta = 113.59(2)degrees, Z = 2 and V = 895.4(5) Angstrom(3). Compound 2 crystallizes in the triclinic space group P ($) over bar 1 with a = 12.220(2) Angstrom, b = 12.465(2) Angstrom, c = 14.272(3) Angstrom, alpha = 80.48(1)degrees, beta = 67.85(1)degrees, gamma = 81.86(1)degrees, Z = 2 and V = 1978(1) Angstrom(3). Compound 3 crystallizes in the space group P2(1)/n with a = 7.464(2) Angstrom, b = 28.832(7) Angstrom, c = 11.221(3) Angstrom, beta = 93.46(2)degrees, Z = 4 and V = 2410(1) Angstrom(3). Compound 4.THF crystallizes in the triclinic space group P ($) over bar 1 with a = 9.734(2) Angstrom, b = 15.797(3) Angstrom, c = 16.79(1) Angstrom, alpha = 111.54(5)degrees, beta = 92.00(5)degrees, gamma = 99.65(1)degrees, Z = 2 and V = 2355(2) Angstrom(3).