Abstract

Representative members of a new family of covalently bonded charge-transfer molecular hybrids, of general formula [(η5-C5H 5)Fe(μ,η6:η1-p-RC6H 4NN)Mo(η2-S2CNEt2)3] +PF6 - (R: H, 5+PF6 -; Me, 6+PF6 -; MeO, 7 +PF6 -) and [(η5-C 5-Me5)Fe(μ,η6:η1-C 6H5NN)Mo(η2-S2CNEt 2)3]+PF6 -, 8 +PF6 -, have been synthesized by reaction of the corresponding mixed-sandwich organometallic hydrazines [(η6- C5H5)Fe(η6-p-RC6H 4NHNH2)]+PF6 - (R: H, 1+PF6 -; Me, 2+PF6 -; MeO, 3+PF6 -) and [(η5-C5Me5)Fe(η6-C 6H5NHNH2)]+PF6 -, 4+PF6 -, with cis- dioxomolybdenum(VI) bis(diethyldithiocarbamato) complex, [MoO2(S 2CNEt2)2], in the presence of sodium diethyldithiocarbamato trihydrate, NaSC(=S)-NEt2·3H 2O, in refluxing methanol. These iron-molybdenum complexes consist of organometallic and inorganic fragments linked each other through a π-conjugated aryldiazenido bridge coordinated in η6 and η1 modes, respectively. These complexes were fully characterized by FT-IR, UV-visible, and 1H NMR spectroscopies and, in the case of complex 7+PF6 -, by single-crystal X-ray diffraction analysis. Likewise, the electrochemical and solvatochromic properties were studied by cyclic voltammetry and UV-visible spectroscopy, respectively. The electronic spectra of these hybrids show an absorption band in the 462-489 and 447-470 nm regions in CH2Cl2 and DMSO, respectively, indicating the existence of a charge-transfer transition from the inorganic donor to the organometallic acceptor fragments through the aryldiazenido spacer. A rationalization of the properties of 5 +PF6 --8+PF6 - is provided through DFT calculations on a simplified model of 7 +PF6 -. Besides the heterodinuclear complexes 5+PF6 --8+PF6 -, the mononuclear molybdenum diazenido derivatives, [(η1-p-RC6H4NN)Mo(η2-S 2CNEt2)3] (R: H, 9; Me, 10; MeO, 11), resulting from the decoordination of the [(η5-C5H 5)Fe]+ moiety of complexes 5+PF 6 --7+PF6 -, were also isolated. For comparative studies, the crystalline and molecular structure of complex 10·Et2O was also determined by X-ray diffraction analysis and its electronic structure computed. © 2007 American Chemical Society.