Dismantling of Vinyl Ethers by Pentanuclear [(iPr3P)Ni]5H6: Facile Cooperative C−O, C−C and C−H Activation Pathways.

Abstract: The [(iPr3P)Ni]5H6 cluster (1) and H2C=CHOtBu react at room temperature to form the new pentanuclear NiH carbide [(iPr3P)Ni]5H4(C)(CO) (3), along with an equivalent of isobutylene. This transformation requires the activation of multiple unreactive bonds, including C−H, C−C, and C(sp3)−O bond cleavage. Analysis of the reaction mixture by 1H NMR revealed the production of two additional paramagnetic species, assigned as [(iPr3P)Ni]4H4(C‐CH3)NiOtBu (4 a) and [(iPr3P)Ni]4H4(C‐CH2OtBu)NiOtBu (5 a), which arise from C(sp2)−O bond cleavage and CH bond rearrangements. The reaction of 1 with H2C=CHOSiMe2CH2Ph produced the isolable 4 a analogue [(iPr3P)4Ni5]H4(CCH3)(OSiMe2CH2Ph) (4 c). An isolable analogue of 5 a was obtained from the reaction of 1 with H2C=CHOAd (Ad=1‐admantyl), which produced [(iPr3P)4Ni5]H4(CCH2OAd)(OAd) (5 d). The utilization of both cluster faces and vertices for bonding substrate fragments in these transformations demonstrates the remarkable flexibility of the robust Ni5H4 core in the cooperative activation of multiple C−O, C−C and C−H bonds. [ABSTRACT FROM AUTHOR]