Reactivity Studies of Oxo–Mo(IV) Complexes Containing Potential Hydrogen-Bond Acceptor/Donor Phenolate Ligands

Reactivity studies of oxo–Mo­(IV) complexes, Tp iPrMoO­{2-OC6H4C­(O)­R-κ2 O,O′} (R = Me, Et, OMe, OEt, OPh, NHPh), containing chelated hydrogen-bond donor/acceptor phenolate ligands are reported. Hydrolysis/oxidation of Tp iPrMoO­(2-OC6H4CO2Ph-κ2 O,O′) in the presence of methanol yields tetranuclear [Tp iPrMoO­(μ-O)2MoO]2(μ-OMe)2 (1), while condensation of Tp iPrMoO­{2-OC6H4C­(O)­Me-κ2 O,O′} and methylamine gives the chelated iminophenolate complex, Tp iPrMoO­{2-OC6H4C­(Me)­NMe-κ2 O,N} (2), rather than the aqua complex, Tp iPrMoO­{2-OC6H4C­(Me)­NMe-κO}­(OH2). The oxo–Mo­(IV) complexes are readily oxidized by dioxygen or hydrogen peroxide to the corresponding cis-dioxo–Mo­(VI) complexes, Tp iPrMoO2{2-OC6H4C­(O)­R}; in addition, suitable one-electron oxidants, e.g., [FeCp2]­BF4 and [N­(C6H4Br)3]­[SbCl6], oxidize the complexes to their EPR-active (g iso ≈ 1.942) molybdenyl counterparts (3, 4). Molybdenyl complexes such as Tp iPrMoOCl­{2-OC6H4C­(O)­R} (5) and Tp iPrMoOCl2 also form when the complexes react with chlorinated solvents. The ester derivatives (R = OMe, OEt, OPh) react with propylene sulfide to form cis-oxosulfido–Mo­(VI) complexes, Tp iPrMoOS­{2-OC6H4C­(O)­R}, that crystallize as dimeric μ-disulfido–Mo­(V) species, [Tp iPrMoO­{2-OC6H4C­(O)­R}]2(μ-S2) (6−8). The crystal structures of [Tp iPrMoO­(μ-O)2MoO]2(μ-OMe)2, Tp iPrMoO­{2-OC6H4C­(Me)­NMe}, Tp iPrMoOCl­{2-OC6H4C­(O)­NHPh}·{2-HOC6H4C­(O)­NHPh}, and [Tp iPrMoO­{2-OC6H4C­(O)­R}]2(μ-S2) (R = OMe, OEt) are reported.