MM quadruply bonded complexes supported by vinylbenzoate ligands: synthesis, characterization, photophysical properties and application as synthonsElectronic 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

From the reactions between M 2 (T i PB) 4 compounds and meta and para -vinylbenzoic acids (2 equiv.) in toluene at room temperature the compounds trans -M 2 (T i PB) 2 L 2 , 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 -Mo 2 (T i PB) 2 (O 2 CC 6 H 4 - m -CH&z.dbd;CH-C 6 H 5 ) 2 , 3A and trans -Mo 2 (T i PB) 2 (O 2 CC 6 H 4 - p -CH&z.dbd;CH-C 6 H 5 ) 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 1 H NMR, IR, UV-visible absorption and emission spectroscopy, high resolution MALDI-TOF 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 M 2 δ to Lπ* charge transfer transitions. The lifetimes of the 1 MLCT state fall in the range of 1-10 ps and for the molybdenum complexes the T 1 states are 3 δδ* with lifetimes ∼50 μs while for the tungsten complexes the T 1 are 3 MLCT with lifetimes in the range of 3-10 ns. MM complexes as potential synthons for the development of higher order extended structures via Heck coupling reactions, exhibiting interesting photophysical properties.