Reactions of molybdenum pentachloride with oxygen and nitrogen donor ligands

The interactions of molybdenum pentachloride (1) with a variety of organic compounds were studied in dichloromethane and the metal products were isolated in the solid state. The 3:1 molar reactions of 1 with OCRR0 (R = R0 = Ph; R = H, R0 = 2-C6H4Me) afforded the complexes Mo(O)Cl3(OCRR0)2 (R = R0 = Ph, 2a; R =H, R0 = 2-C6H4Me, 2b) in high yields. Compound Mo(O)Cl3[O(CH)3CC(O)CH3] , 3, was isolated in 35% yield from 1 and 2-acetylfuran. The 1:1 reaction of 1 with phenazine (C12H8N2) 1 resulted in the formation of MoCl5(C12H8N2), 4; the oxydo-chloride derivative Mo(O)Cl3[j1(N)-C12H8N2], 5, was prepared straightforwardly by addition of phenazine to Mo(O)Cl3, formed in situ upon treatment of 1 with tetrahydrofuran. The addition of a twofold excess of Me2NCH2CH2CO2Me to 1 afforded MoCl4[j1(N)-Me2NCH2 CH2CO2Me]2, 6, in 72% yield. The reaction of 1 with MeO2CC,,CCO2Me led to a mixture of inseparable products: MoOCl3(j1-MeO2CC,,CCO2Me)2, 7a, MoCl5(j1-MeO2CC,,CCO2Me), 7b, and MoCl4(j1-MeO2 CC,,CCO2Me)2, 7c, were recognized by combined EPR/DFT investigation. Analogous DFT/EPR studies were performed on 2b and 4. The X-ray structures of 2a, 3 and 5 were determined; the X-ray structure of 5 represents a rare example of crystallographically-characterized pentacoordinated Mo(V) neutral complex.