10.1021/jp108544v.s001 Brian G. Alberding Brian G. Alberding Malcolm H. Chisholm Malcolm H. Chisholm Terry L. Gustafson Terry L. Gustafson Yao Liu Yao Liu Carly R. Reed Carly R. Reed Claudia Turro Claudia Turro Photophysical Studies of <i>trans</i>-Bis(phenylethynyldiisopropylamidinato)bis(acetato)dimetal Complexes Involving MM Quadruple Bonds Where M = Mo or W American Chemical Society 2010 T 1 states II T 1 absorption MM Quadruple Bonds S 1 states S 1 Mo emission compound 1 MLCT T 1 state 2010-12-09 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Photophysical_Studies_of_i_trans_i_Bis_phenylethynyldiisopropylamidinato_bis_acetato_dimetal_Complexes_Involving_MM_Quadruple_Bonds_Where_M_Mo_or_W/2706277 The title compounds <i>trans</i>-M<sub>2</sub>(O<sub>2</sub>CMe)<sub>2</sub>[C(<i><sup>i</sup></i>PrN)<sub>2</sub>CCPh]<sub>2</sub>, <b>I</b> (M = Mo) and <b>II</b> (M = W), show electronic absorptions in the visible region of the spectrum assignable to <sup>1</sup>MLCT [M<sub>2</sub>δ to phenylethynylamidinate π*]. These compounds show dual emission from S<sub>1</sub> and T<sub>1</sub> states. For both <b>I</b> and <b>II</b>, S<sub>1</sub> is <sup>1</sup>MLCT, but for <b>I</b> the T<sub>1</sub> state is shown to be MMδδ* while for <b>II</b> T<sub>1</sub> is <sup>3</sup>MLCT. The lifetimes of the S<sub>1</sub> and T<sub>1</sub> states have been determined by femtosecond and nanosecond transient absorption spectroscopy: for <b>I</b> S<sub>1</sub> ∼ 20 ps and T<sub>1</sub> ∼ 100 μs and for <b>II</b> S<sub>1</sub> ∼ 6 ps and T<sub>1</sub> ∼ 5 μs. From solvent dependence of the absorption and emission spectra, we suggest that the S<sub>1</sub> states are localized on one amidinate ligand though the initial absorption is to a delocalized state.