Structure and Reactivity of [Ru–Al] and [Ru–Sn] Heterobimetallic PPh3‑Based Complexes

Treatment of [Ru­(PPh3)­(C6H4PPh2)2H]­[Li­(THF)2] with AlMe2Cl and SnMe3Cl leads to elimination of LiCl and CH4 and formation of the heterobimetallic complexes [Ru­(C6H4PPh2)2{PPh2C6H4AlMe­(THF)}­H] 5 and [Ru­(PPh3)­(C6H4PPh2)­(PPh2C6H4SnMe2)] 6, respectively. The pathways to 5 and 6 have been probed by variable temperature NMR studies, together with input from DFT calculations. Complete reaction of H2 occurs with 5 at 60 °C and with 6 at room temperature to yield the spectroscopically characterized trihydride complexes [Ru­(PPh2)2{PPh2C6H4AlMe}­H3] 7 and [Ru­(PPh2)2{PPh2C6H4SnMe2}­H3] 8. In the presence of CO, 6 forms the acylated phosphine complex, [Ru­(CO)2(C­(O)­C6H4PPh2)­(PPh2C6H4SnMe2)] 9, through a series of intermediates that were identified by NMR spectroscopy in conjunction with 13CO labeling. Complex 6 undergoes addition and substitution reactions with the N-heterocyclic carbene 1,3,4,5-tetramethylimidazol-2-ylidene (IMe4) to give [Ru­(IMe4)2(PPh2C6H4)­(PPh2C6H4SnMe2)] 10, which converted via rare N-Me group C–H activation to [Ru­(IMe4)­(PPh3)­(IMe4)′(PPh2C6H4SnMe2)] 11 upon heating at 60 °C and to a mixture of [Ru­(IMe4)2(IMe4)′(PPh2C6H4SnMe2)] 12 and [Ru­(PPh3)­(PPh2C6H4)­(IMe4-SnMe2)′] 13 at 120 °C.