MM quadruply bonded complexes supported by vinylbenzoate ligands: synthesis, characterization, photophysical properties and application as synthons† †Electronic supplementary information (ESI) available: Transient absorption plots and kinetics, time resolved IR plots, NIR emission. CCDC 1015787 and 1015788. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4sc02542c Click here for additional data file. Click here for additional data file.

From the reactions between M2(T i PB)4 compounds and meta and para - vinylbenzoic acids (2 equiv) in toluene at room temperature the compounds trans-M2(T i PB)2L2, where L = m-vinylbenzoate 1A (M = Mo) and 1B (M = W) and T i PB = 2,4,6-triisopropylbenzoate, and where L = p-vinylbenzoate 2A (M = Mo) and 2B (M = W) have been isolated. Compounds 1A and 2A have been shown to undergo Heck carbon-carbon coupling reactions with phenyliodide to produce trans-Mo2(T i PB)2(O2CC6H4-m-CH=CH-C6H5)2,3A and trans-Mo2(T i PB)2(O2CC6H4-p-CH=CH-C6H5)2, 4A. The molybdenum compounds 1A and 2A have been structurally characterized by single crystal X-ray crystallography. All the new compounds have been characterized by 1H NMR, IR, UV-Visible absorption and emission spectroscopy, high resolution MALDITOF MS, fs- and ns- transient absorption spectroscopy and fs- time-resolved IR spectroscopy. Electronic structure calculations employing density functional theory, DFT, and time-dependent DFT have been employed to aid in the interpretation of spectral data. All compounds show intense absorptions in the visible region corresponding to M2δ to Lπ* charge transfer transitions. The lifetimes of the 1MLCT state fall in the range of 1 - 10 ps and for the molybdenum complexes the T1 states are 3δδ* with lifetimes ~50 μs while for the tungsten complexes the T1 are 3 MLCT with lifetimes in the range of 3 - 10 ns.