Unsymmetrical 1,4-diazabutadiene complexes of platinum(II)

The new unsymmetrical 1,4-diazabutadiene ligand glyoxal bis(2-(methoxymethyl)-4,6-di-tert-butylphenyl)diimine (L) and its reduced analog (LH4) were synthesized. The reactions of both ligands with bis(benzonitrile) complexes of palladium and platinum, MCl2(PhCN)(2), were investigated. Two isomers of formula MCl2L were isolated from the reaction of L with MCl2(PhCN)(2) (1a and Pk, for Pd, 2a and 2b for Pt), while only a single product, MCl2(LH4), formed in the reaction with LH4 (3 for M = Pd, 4 for M = Pt). All new compounds were characterized by elemental analyses and IR and NMR spectroscopies, The molecular structures for L, LH4, 2b, 3, and 4 were determined by single-crystal X-ray diffraction. The metal complexes exhibit distorted square-planar geometry. The aryl groups of the L and LH4 Ligands lie out of the coordination plane in a manner that blocks potential axial ligation sites. Ligand L crystallizes in the triclinic space group <P(1)over bar> with a = 5.760(1) Angstrom, b = 9.383(2) Angstrom, c = 14.954(3) Angstrom, alpha = 89.38(2)degrees, beta = 79.67(2)degrees, gamma = 88.14(2)degrees, and Z = 1. The reduced ligand LH4 crystallizes in the monoclinic space group P2(1) with a = 5.9758(1) Angstrom, b = 17.4272(2) Angstrom, c = 15.6222(1) Angstrom, beta = 99.063(1)degrees, and Z = 2. Complex 2b crystallizes in the monoclinic space group P2(1)/c with a = 16.9599(2) Angstrom, b = 18.4985(2) Angstrom, c = 12.4976(0) Angstrom, beta = 100.945-(0)degrees and Z = 4, Complex 3 crystallizes in the monoclinic space group C2/c with a = 36.1506(8) Angstrom, b = 8.0904 (2) Angstrom, c = 15.5671(1) Angstrom, beta = 113.988(1)degrees, and Z = 4. Complex 4 crystallizes in the monoclinic space group C2/c with a = 36.0649(3) Angstrom, b = 8.1787(2) Angstrom, c = 15.7585(3)Angstrom, beta = 112.610(1)degrees, and Z = 4.