A Structural and Spectroscopic Investigation of Octahedral Platinum Bis(dithiolene)phosphine Complexes: Platinum Dithiolene Internal Redox Chemistry Induced by Phosphine Association

作者：Chandrasekaran P^*; Greene Angelique F; Lillich Karen; Capone Stephen; Mague Joel T; DeBeer Serena; Donahue James P

来源：Inorganic Chemistry, 2014, 53(17): 9192-9205.

DOI：10.1021/ic501273b

The complexes [Pt(mdt)(2)] (4; mdt = methyldithiolene, [Me2C2S2](n-)), [Pt(adt)(2)] (5; adt = p-anisyldithiolene, [(MeO-p-C6H4)(2)C2S2](n-)), and [Pd(adt)(2)] (10) have been prepared in yields of %26gt;= 90% via transmetalation reactions with the corresponding [R2Sn(S2C2R%26apos;(2))] complexes (R = Bu-n, R%26apos; = Me; R = Me, R%26apos; = -C6H4-p-OMe, 3). Intraligand C-S and C-C-chelate, bond lengths (similar to 1.71 and similar to 1.40 angstrom, respectively) obtained by X-ray crystallography show these compounds to be comprised of radical monoanions mdt(center dot-) and adt(center dot-). The six-coordinate octahedral adducts [Pt(adt)(2)(dppe)] [6; dppe = 1,2-bis(diphenylphosphino)ethane], trans-[Pt(adt)(2)(PMe3)(2)] (8), and trans-[Pt(mdt)(2)(PMe3)(2)} (9) have also been prepared, and crystal structures reveal dithiolene ligands that are fully reduced ene-1,2-dithiolates (C-S and C-C-chelate = similar to 1.77 and 1.35 angstrom, respectively). Reduction of the dithiolene ligand thus occurs to accommodate the +IV oxidation state typical of octahedral six-coordinate platinum. The cyclic voltammogram of 5 shows two fully reversible reductions at -0.11 and -0.84 V in CH2Cl2 (vs Ag/AgCl), attributed to successive (adt(center dot-) + e(-) -%26gt; adt(2-)) processes, and a reversible oxidation at +1.01 V. The cyclic voltammogram of 9 shows two reversible oxidations at +0.38 and +0.86 V, which are assigned as successive (adt(2-) -%26gt; adt(center dot-) + e(-)) oxidations. Consistent with their formulation as having fully reduced dithiolene ligands, the UV-vis spectra for 6, 8, and 9 show no low-energy absorptions below 700 nm, and the S K-edge XAS spectra of 6 and 8 show dithiolene sulfur that is reduced relative to that in 5. The introduction of PMe3 to 10 did not produce the palladium analogue of 8 but rather [Pd(adt)(PMe3)(2)] (11). The reaction of [PdCl2(PPh3)(2)] with Li-2(mdt) produced a mixture of [Pd(mdt)(PPh3)2] (12, 20%) and [(Ph3P)Pd(mu-1,2-mdt-S,S%26apos;:S)(2)Pd(PPh3)] (13, 28%), with the latter having C-2 symmetry with a Pd2S2 core structure folded along the S ... S axis.

• 出版日期2014-9-1