Hydridic Character and Reactivity of Di[1,2-bis- (dimethylphosphino)ethane]hydridonitrosylmolybdenum(0)

Abstract

The synthesis of the tetraphosphine-substituted molybdenum hydride complex trans-Mo(dmpe)2(H)(NO) (3) (dmpe = bis(dimethylphosphino)ethane) is described, which is obtained by starting from the known compound Mo(CO)4(NO)(ClAlCl3) via the isolable chloride trans-Mo(Cl)(dmpe)2(NO) (1) and the borohydride trans-Mo(η1-BH4)(dmpe)2(NO) (2). Two deuteride complexes trans-Mo(dmpe)2(D)(NO) (3a) and mer-Mo(CO)(D)(NO)(PMe3)3 (4) have been prepared. From these the Mo−D bond ionicities of both deuterides were obtained via determinations of the deuterium quadrupole coupling constants (DQCC) in solution from T 1min measurements of the 2H nucleus and in solid state from static 2H NMR spectra. A strongly polar character of the Mo−D(H) bond was found for 3 and 4. In agreement with its enhanced hydridicity 3 revealed a very high propensity for hydride transfer reactions. It reacted readily with benzophenone, acetophenone, and acetone to afford the corresponding alkoxide complexes trans-Mo(dmpe)2(NO)(OCHRR‘) (R = R‘ = Ph (5); R = Me, R‘ = Ph (6); R = R‘ = Me (7)). 3 also underwent rapid insertion with Fe(CO)5 and Re2(CO)10 to afford μ-formyl complexes Mo(dmpe)2(NO)[(μ-OCH)Fe(CO)4] (8) and Mo(dmpe)2(NO)[(μ-OCH)Re2(CO)9] (9), respectively. Furthermore, reversible double insertion of 3 into Re2(CO)10 was observed, which furnished the (ON)(dmpe)2Mo(μ-OCH)Re2(CO)8(μ-CHO)Mo(dmpe)2(NO) complex (10). For this reaction equilibrium constants were determined by VT-NMR measurements. ΔH and ΔS amount to −58.8 ± 2.7 kJ mol-1 and −48 ± 2 J·K-1.mol-1. The reaction of 3 with Mn2(CO)10 gave the μ-carbonyl complex Mo(dmpe)2(NO)[(μ-OC)Mn(CO)4] (12) via the intermediacy of Mo(dmpe)2(NO)[(μ-OCH)Mn2(CO)9] (11). The structures of compounds 1, 2, 8, 9, 10, and 12 were studied by single-crystal X-ray diffraction.

Hydride Route for the Palladium‐Catalysed Cyclocarbonylation of Monoterpenes

“…As a consequence, this complex presents a high propensity to undergo hydride-transfer reactions. [17] The 1 H NMR spectrum of complex 5 at 183 K shows the additional presence of a small amount of complex 2 (Figure 2). Increasing the temperature to 203 K leads to a large increase in the concentration of 2 due to decoordination of SnCl 2 , complex 5 becoming the minor species.…”

Molybdenum Nitrosyl Complexes and Their Application in Catalytic Imine Hydrogenation Reactions

“…[26,27] In addition we would expect for the deprotonated dihydrogen complexes the weakening of the resulting metal-hydride bonds to facilitate hydride transfers onto unsaturated compounds. [28,29] Based on this we supposed that (diphosphane)nitrosyl complexes of the type [Mo(NO)(PʝP)(CO) 2 L][A] (L = labile ligand) might render catalytic ionic hydrogenation systems, particularly for imine hydrogenations with proton-before-hydride transfer characteristics. Figure 1.…”

Hydride Transfer Reactivity of Mo(L)(H)(depe)2 (L = N, NBEt3)

“…[25] The reactivity patterns of related hydrido complexes with trans ligands L = NO and CMes were reported earlier so that it remains to study the influence of the nitrido ligand. [14,[17][18][19][20] We describe here the synthesis of molecules based on nitrido ligands such as Mo(H)(L)(depe) 2 (L = N and NBEt 3 ) and we present also reactivity studies carried out with the Mo(H)(NBEt 3 )(depe) 2 complex.…”