Photochemical and chemical oxidation of α-dimine-dithiolene metal complexes:: Insight into the role of the metal atom

[Pd(bpy)(bdt)], 2 (bpy = 2,2'-bipyridine, bdt = 1,2-benzenedithiolate), was prepared in good yield by the reaction of bdtNa(2) with [(bpy)PdCl2] in DMSO. The analogous nickel complex, 1, was prepared in a similar reaction using MeOH/CH2Cl2 and [(bpy)NiCl2. dmf](2). Both 1 (a = 7.99'10(1) Angstrom, b = 11.4385(1) Angstrom, c = 16.1415(1) Angstrom, beta = 103.327(1)degrees, V = 1435.86(2) Angstrom (3), Z = it) and 2 (a = 8.1631(5) A, b = 11.4379(7) Angstrom, c = 16.2475(10) Angstrom, beta = 103.7010(10)degrees V = 1473.84(12) Angstrom (3), Z = 4) crystallize in the monoclinic space group P2(1)/c and are isostructural with their previously reported platinum analogue. In accord with the results observed for platinum but not nickel, photochemical oxidation of 2 in DMF provides the monosulfinate complex [Pd(bpy)(bdtO(2))], 4, along with a minor amount of the corresponding disulfinate [Pd(bpy)(bdtO(4))], 5, while chemical oxidation yields only the latter. 4 cocrystallizes with 5 in the monoclinic space group P2(1)/c (a = 8.026(3) Angstrom, b = 14.600(6) Angstrom, c = 13.371(3) Angstrom, beta = 101.80(3)degrees, V = 1533.8(9) Angstrom (3), Z = 4) as does pure 5 (a = 8.5611(9) Angstrom, b = 14.4586(15) Angstrom, c = 13.3677(14) Angstrom. beta = 108.122(2)degrees, V = 1572.6(3) Angstrom (3), Z = 4). Comparison of spectroscopic and electrochemical properties of the three complexes, [M(bpy)(bdt)], yields the following ordering for the energy of the HOMO: Pd < Ni < Pt. The observed reactivity patterns and the electronic data suggest that the "anomalous" reactivity of 1 be attributed to the greater relative flexibility of the coordination geometry for nickel(II) complexes rather than electronic differences such as the energies of the frontier orbitals.