Molybdenum(II) Complexes with -Diimines: Catalytic Activity in Organic and Ionic Liquid Solvents

The new [MoX((3)-C3H5)(CO)(2)(-diimine)] complexes with: (i) X = Br or triflate and -diimine = 1,10-phenanthroline (phen) and dipyridophenazine (dppz); and (ii) X = Br and -diimine = phen and dppz, with several substituents, are synthesized and characterized. The structures of [MoBr((3)-C3H5)(CO)(2)(Cl-phen)] and [Mo(CF3SO3)((3)-C3H5)(CO)(2)(dppz)] are determined by using single-crystal X-ray diffraction. These and three complexes of 2,2-bipyridyl (bpy), and its two derivatives with Me and tBu substituents, are tested in the homogeneous catalytic epoxidation of several olefins in dichloromethane, exhibiting, in general, a good selectivity towards the respective epoxide and relatively low TOFs. For the first time, the oxidation of cis-cyclooctene with some of these catalysts is also conducted in a variety of room-temperature ionic liquids (RTILs). In the presence of [MoBr((3)-C3H5)(CO)(2)(phen)], the conversions, in general, increase, compared with the reactions in organic solvents. Interestingly, different chemoselectivity is found when [C(6)mim][Ntf(2)] and [C(2)mim][FAP] are used with diol (24-26%). On the other hand, [MoBr((3)-C3H5)(CO)(2)(L)] (L = Me-phen or dppz) exhibits much lower conversions in the RTILs tested than in common organic solvents.