Molybdenum(VI) imido complexes: formation of [Mo(NPh)(S2CNR2)3]X and [Mo(NPh)(S2CNR2)2(μ-MoO4)]2 (R = Me, Et) from the reaction of [MoO2(S2CNR2)2] and PhNCO under aerobic conditions

Abstract

Products from the thermolysis of PhNCO and [MoO 2 (S 2 CNR 2 ) 2 ] (R = Me, Et) are highly dependent upon the reaction conditions. When carried out in air, the major products are cations, [Mo(NPh)(S 2 CNR 2 ) 3 ] ? , as shown by a crystal structure of [Mo(NPh)(S 2 CNEt 2 ) 3 ] 2 [Mo 6 O 19 ]. Under rigorously anaerobic conditions, reaction of two equivalents of PhNCO with [MoO 2 (S 2 CNR 2 ) 2 ] affords [Mo(NPh) 2 -(S 2 CNR 2 ) 2 ] as the major product. However, chloroform solutions of the bis(imido) complexes hydrolyze in air to afford [Mo(NPh)(S 2 CNR 2 ) 2 (l-MoO 4 )] 2 , in which molybdate groups bridge between molybdenum(VI) imidobis(dithiocarbamate) centers. These results are placed in context of our earlier studies of these reactions that lead to the formation of oxo-disulfide [MoS 2 (NPh)(S 2 CNR 2 ) 2 ] and dimeric molybdenum(V) [MoO(l-NPh)(S 2 CNR 2 )] 2 complexes, thus allowing a full picture of these transformations to be established.

The mechanism and kinetics of propene ammoxidation over α-bismuth molybdate

“…These very unfavorable thermodynamics for formation of Mo=NH groups suggests that in the presence of water, produced as a byproduct of propene ammoxidation (> 3 mol H 2 O produced / mol C 3 H 6 consumed), the surface concentration of Mo=NH groups should be very small. The instability to hydrolytic decomposition in air at room temperature of Mo 6+ =NR groups in organometallic complexes has also been reported [35,36,37]. We note further that theoretical calculations of the transition state enthalpy change for the reaction of an allyl species with a Mo 3 O 9 cluster to produce bound acrolein is 10.9 kcal/mol [38], and the transition state enthalpy change for the reaction of allyl species with a Mo 3 O 8 NH cluster to produce bound acrylonitrile is very similar at 11.4 kcal/mol [39].…”