Magnetic properties, infrared spectroscopy, thermal and theoretical studies of oxomolybdenum(V) complexes with 2,2 '-bipyrimidine

Mono- and dinuclear complexes of oxomolybdenum(V) with 2,2'-bipyrimidine (bpym), MoOCl3(bpym) (1) as two geometric isomers (violet and brown), Mo2O3Cl4(bpym)(2) (2), Mo2O4Cl2(bpym)(2) (3), and Mo2O2Cl6(mu-bpym) (4), have been prepared and characterized by EPR, electronic, infrared and Raman spectroscopy, thermal analysis and theoretical calculations. Magnetic susceptibilities in the 4.6-290 K range show different magnetic behavior for the MoO3+, Mo2O34+ and Mo2O2 (mu-bpym)(6+) units. The EPR spectra have also been registered. Theoretical calculations converged to two stable isomers named cis and trans for MoOCl3(bpym), Mo2O3Cl4(bpym)(2) and for Mo2O4Cl2(bpym)(2) but four isomers for Mo2O2Cl6(mu-bpym). Based on the theoretical and experimental results for the violet and brown 1, we assume that both cis and trans isomers are present in the solid state. This could also explain the existence of two isomers in Mo2O2Cl6(mu-bpym).