Heterobimetallic complexes composed only of first-row transition metals [(TMTAA)V(IV)═O→M(II)Py5Me2](OTf)2 (TMTAA = 7,16-dihydro-6,8,15,17-tetramethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine; Py5Me2 = 2,6-bis(1,1-bis(2-pyridyl)ethyl)pyridine; M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II); OTf = trifluoromethanesulfonate) have been synthesized through a dative interaction between a terminal oxido and M(II) metal centers. This is the first series of V(IV)═O→M(II) heterobimetallic complexes containing an unsupported oxido bridge. Among these five complexes, only V(IV)═O→Fe(II) (3b) has a clear new absorption band upon formation of the dinuclear species (502 nm, ε = 1700 M(-1) cm(-1)). This feature is assigned to a metal-to-metal charge transfer (MMCT) transition from V(IV) to Fe(II), which forms a V(V)-O-Fe(I) excited state. This assignment is supported by electrochemical data, electronic absorption profiles, and resonance Raman spectroscopy and represents the first report of visible-light induced MMCT in a heterobimetallic oxido-bridged molecule where the electron originates on a d(1) metal center.

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We present a new synthetic method for the bis­(dimethyl)­phosphines Me4PCP (C6H4-2,6-(CH2P­(CH3)2)2) and DMPE ((CH3)2PCH2CH2P­(CH3)2) that starts from an aminophosphine, Et2NPMe2. Two equivalents of Et2NPMe2 react with the corresponding bis­(alkyl bromide) to afford an oxygen- and moisture-stable aminophosphonium salt. NaAlH4 selectively reduces the aminophosphonium salt to the desired phosphine. Each step is high yielding and requires minimal purification.

Compared to analogous sterically demanding complexes, the methyl derived pincer iridium complex shows enhanced reactivity with H2 including: rapid isomerization from a cis- to trans-dihydride complex and solvent activation during isomerization.