Crystal structures of two dioxomolybdenum complexes stabilized by salan ligands featuring phenyl and cyclohexyl backbones

Abstract

Two cis-dioxomolybdenum complexes based on salan ligands with different backbones are reported. The first complex, dioxido{2,20-[l,2-phenylenebis(iminomethylene)]bis(phenolato)}molybdenum(VI) dimethylformamide disolvate, [Mo(C20H18N2O2)O2]2C3H7NO (PhLMoO2, 1b), features a phenyl backbone, while the second complex, (6,60-{[(cyclohexane-1,2-diyl)bis(azane-diyl)]bis(methylene)}bis(2,4-di-tert-butylphenolato))dioxidomolybdenum(VI) methanol disolvate, [Mo(C36H56N2O2)O2]2CH3OH (CyLMoO2, 2b), is based on a cyclohexyl backbone. These complexes crystallized as solvated species, 1b2DMF and 2b2MeOH. The salan ligandsPhLH2 (1a) andCyLH2 (2a) coordinate to the molybdenum center in these complexes 1b and 2b in a2N2O fashion, forming a distorted octahedral geometry. The Mo—N and Mo—O distances are 2.3475 (16) and 1.9567 (16) Å, respectively, in 1b while the corresponding measurements are Mo—N = 2.3412 (12) Å, and Mo—O = 1.9428 (10) Å for 2b. A key geometrical feature is that the N—Mo—N angle of 72.40 (4) inCyLMoO2 is slightly less than that of thePhLMoO2 angle of 75.18 (6), which is attributed to the flexibility of the cyclohexane ring between the nitrogen as compared to the rigid phenyl ring in thePhLMoO2