Co-ordination chemistry of dimethylgold(III). Synthesis, spectroscopic, and structural studies of complexes with neutral aromatic nitrogen-donor ligands

Dimethylgold(iI1) nitrate reacts with neutral ligands to form the complexes [AuMe,(tpm)] N03*2H20 (tpm = tri-2-pyridylmethane) and [AuMe2L]N03 [ L = tri-2-pyridylmethanol (tpmo), di -2- pyridylmethane (dpm) , aa-di-2-pyridyltoluene (dpt), di- 1 - pyrazolylmet hane (dpzm) , and tri-1 -pyrazolylmethane (tpzm)]. The crystal structures of complexes of tpzm, tpm, and dpt have been determined by single-crystal X-ray diffraction at 295 K and refined by least-squares methods to R = 0.033, 0.029, and 0.042 for 3 043, 1 616, and 2 529 independent ' observed * reflections, respectively. In these structures the [AuMe,L] + cations have essentially cis-square-planar co-ordination for gold(m), AuC2N2, with Au-C 2.023(7)-2.041(12) A and Au-N 2.1 27(8)-2.142(8) A. In complexes of the potential tridentate ligands one pyridyl group is not co-ordinated in the tpm complex, and one pyrazolyl group is involved in a weak axial Au N interaction [3.139(7) A] in the tpzm complex. Comparison of the H n.m.r. spectra of complexes of the potentially tridentate ligands (tpzm, tpm, and tpmo) with model complexes of bidentate ligands (dpzm, dpm, and dpt) suggests that the co-ordination behaviour of the ligands in methanol resembles that found in the solid state. Crystal data : [AuMe,(tpzm)]NO,, monoclinic, space group P2,/n, a = 16.72(1), b = 9.662(3), c = 10.700(4) A, f3 = 107.83(3)", Z = 4; [AuMe2(tpm)]N03*2H20, orthorhombic, space group P212121, a = 18.56(1), b = 11.150(7), c = 9.983(7) A, Z = 4; [AuMe2(dpt)]N03, monoclinic, P21/n, a = 14.1 42(6), b = 13.01 2(7), c = 10.372(3) A, p = 100.60(3)", Z = 4.Full Tex