The preparation and characterization of the compounds trans-M 2(TiPB)2(O2C-CHCH-2-C 4H3S)2 where M = Mo or W and TiPB = 2,4,6-triisopropylbenzoate are reported. The optical spectra of the new compounds are compared with those of related trans-M2(T iPB)2L2 compounds where L = O 2C-C6H4-4-CN, O2C-α, α′-terthienyl (TTh), and O2C-4-C6H 4N-B(C6F5)3, that show strong metal-to-ligand charge transfer bands because of M2δ to Lπ conjugation, and are notably temperature dependant due to the various conformations of the two trans-L groups. Upon cooling the spectral features sharpen as the planar geometry that optimizes M2δ-Lπ conjugation is favored. As the electronic coupling of the two trans-Lπ systems increases the (0,0) electronic transition gains intensity indicating a greater nesting of the ground state (S0) and excited state (S 1) potential energy surfaces. These features are discussed in terms of the related electronic coupling of [M2]-[M2] complexes.
All Science Journal Classification (ASJC) codes
- Inorganic Chemistry