194282-30-9Relevant articles and documents
Synthesis and Properties of Heterocyclic Substituted 1,2-Enedithiolates of Nickel, Palladium, and Platinum
Kaiwar, Sharada P.,Hsu, John K.,Liable-Sands, Louise M.,Rheingold, Arnold L.,Pilato, Robert S.
, p. 4234 - 4240 (2008/10/09)
A convenient new synthetic route to metallo-1,2-enedithiolates was applied to the synthesis of (dppe)M{S2C2-(heterocycle)(H)}; dppe = 1,2-bis(diphenyldiphosphino)ethane, M = Ni, Pd, and Pt, and heterocycle = 2-quinoxaline, 2-, 3-, and 4-pyridine, and 2-pyrazine. These complexes were prepared from the corresponding bis(hydrosulfido) complexes (dppe)M(SH)2 and the α-bromo ketones, heterocycle-C(O)CH2Br. In the solid state, (dppe)Ni{S2C2(2-pyrazine)(H)} is a slightly distorted square plane with a planar five-membered metallo-1,2-enedithiolate ring. The metallo-1,2-dithiolate is ≈6° from being coplanar with the pyrazine ring. These complexes all have a UV-visible band assignable to an intraligand transition (ILCT) that is best described as a 1,2-enedithiolate π → heterocycle π* charge transfer transition. The energy of the ILCT transition tracks with the reduction potential of the appended aromatic heterocycle. The pKa of the protonated complexes is 1-3 units higher than that of the parent heterocycle, independent of the metal, and consistent with resonance stabilization of the protonated heterocycle by the 1,2-enedithiolate ligand.
