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Laboratories for Inorganic Materials (Chemistry Department) and the Canadian Centre for Picosecond Laser Flash Photolysis, Concordia University, 1455 de Maisonneuve W. Montreal, Quebec, H3G 1M8, Canada Manuscript received24 January1991 The photochemically interesting interaction of methylviologen and metal maleonitriledithiolate complexes has been investigated by absorption, emission and transient absorption spectroscopy. Ion-pair charge transfer bands for the (MV2+)[\(Pt(mnt)_{2}^{2-}\)] and (MV2+)[\(Ni(mnt)_{2}^{2-}\)] have been identified in the near-ir. The results presented here suggest that both the complexes mentioned above display weak higher energy state CT absorption bands attributed to weak coupling between the cation and anion. Photoexcitation of either complex in the MLCT region results in electron transfer from the donor mnt molecule to the acceptor planar methylviologen molecule producing an excited state. These complexes display room temperature emission which is not observed with conventional alkylammonium cations. The emission and excited state absorption spectra are consistent with a species resembling a reduced dimeric viologen paired with the planar \(M(mnt)_{2}^{-}\). Picosecond transient absorption spectroscopy indicates an excited state lifetime of 0.9±0.2 ns for the species produced from the platinum complex. |
