Conversion of Benzaldehyde Imines into Isocyanides at a Low-Valent Molybdenum Center. Preparation and Reactivities of Isocyanide−Dinitrogen Complexes trans-[Mo(RNC)(N2)(Ph2PCH2CH2PPh2)2] (R = Aryl, Alkyl)1

Abstract

The molybdenum dinitrogen complex trans-[Mo(N2)2(dppe)2] (1; dppe = Ph2PCH2CH2PPh2) reacts with benzaldehyde imines PhCHNR (R = Ph, C6H4Me-p, C6H4OMe-p, C6H4F-p, C6H4NMe2-p, Bun, Pri, CH2Ph) in benzene at reflux to give a series of isocyanide−dinitrogen complexes trans-[Mo(RNC)(N2)(dppe)2] (7) with the concurrent formation of benzene. The structure of 7a (R = Ph) has been determined by X-ray crystallography. Treatment of 7a and 7f (R = Bun) with CO (1 atm) or p-MeOC6H4CN results in the replacement of the coordinated N2 by these ligands, affording trans-[Mo(RNC)(L)(dppe)2] (L = CO (9), p-MeOC6H4CN (10)). The complex containing two different isocyanides trans-[Mo(PhNC)(ButNC)(dppe)2] was obtained analogously from 7a and ButNC. On the other hand, when benzene or toluene solutions of 7a and 7e (R = C6H4NMe2-p) were first heated under Ar up to 80−90 °C for a short period to dissociate the coordinated N2 and then treated with H2 at room temperature, dihydrogen complexes trans-[Mo(RNC)(η2-H2)(dppe)2] (13) were p...