The preparation of trans-Mo-2((TPB)-P-i) 2(O2C-2-AnQ) (2), I, and Mo-2(DAniF)(3)(O2C-2-AnQ), II, where, O2C-2-AnQ = 9,10-anthraquinone-2-carboxylate, (TPB)-P-i = 2,4,6-triisopropylbenzoate and DAniF = N, N'-di-(p-anisyl) formamidinate are described together with electronic structure calculations employing density functional theory on model compounds. Compounds I and II have been further characterized by H-1 NMR spectroscopy, MALDI-TOF mass spectrometry, electrochemical studies, UV-vis-NIR and steady state emission spectroscopy, time-resolved (fs and ns) transient absorption and infrared spectroscopy. Compound II has been structurally characterized by a single crystal X-ray crystallography study. Both compounds show metal-to-ligand charge transfer transitions, (MLCT)-M-1, corresponding to Mo-2 delta to L Pi(*) (L = O2C-2-AnQ) and have S-1 states with relatively long lifetimes (tau(I) similar to 8 ps; tau(II) similar to 2 ps). Femtosecond time resolved IR studies, fs-TRIR indicate that for I, despite its relatively small HOMO-LUMO gap, and II the negative charge in the S-1 state resides on one anthraquinone carboxylate ligand. For II, fs-TRIR spectroscopy detects the Mo-2 (3)delta delta(*) state with tau similar to 100 ns despite the presence of a lower energy (MLCT)-M-3 state. This, together with earlier findings indicates a significant kinetic barrier to the interconversion of MLCT and Mo-2 delta delta(*) states.
