6628-21-3Relevant articles and documents
Zinc-mediated carbene insertion to C-Cl bonds of chloromethanes and isolable zinc(II) isocyanide adducts
Kulkarni, Naveen V.,Das, Animesh,Jayaratna, Naleen B.,Yousufuddin, Muhammed,Rasika Dias
, p. 5151 - 5153 (2015)
The zinc adduct {[HB(3,5-(CF3)2Pz)3]Zn}+, which was generated from [HB(3,5-(CF3)2Pz)3]ZnEt and [Ph3C]{B[3,5-(CF3)2C6H3]4}, catalyzes the activation of C-halogen bonds of chloromethanes via carbene insertion. Ethyl diazoacetate serves as the carbene precursor. The presence of {[HB(3,5-(CF3)2Pz)3]Zn}+ in the reaction mixture was confirmed by obtaining {[HB(3,5-(CF3)2Pz)3]Zn(CNtBu)3}+ using CNtBu as a trapping agent. {[HB(3,5-(CF3)2Pz)3]Zn(CNtBu)3}+ loses one zinc-bound CNtBu easily to produce five-coordinate {[HB(3,5-(CF3)2Pz)3]Zn(CNtBu)2}+.
Enhanced Electrophilicity of Heterobimetallic Bi-Rh Paddlewheel Carbene Complexes: A Combined Experimental, Spectroscopic, and Computational Study
Collins, Lee R.,Van Gastel, Maurice,Neese, Frank,Fürstner, Alois
supporting information, p. 13042 - 13055 (2018/10/15)
Dirhodium paddlewheel complexes are indispensable tools in modern organometallic catalysis for the controlled decomposition of diazo-compounds. Tuning the reactivity of the thus-formed transient carbenes remains an active and dynamic field of research. Herein, we present our findings that the distal metal center plays an as yet underappreciated role in modulating this reactivity. Replacement of one rhodium atom in the bimetallic core for bismuth results in the formation of a significantly more electrophilic carbene complex. Bismuth-rhodium catalysts thereby facilitate previously unknown modes of reactivity for α-diazoester compounds, including the cyclopropanation of alkenes as electron deficient as trichloroethylene. While dirhodium paddlewheel complexes remain the catalysts of choice for many carbene-mediated transformations, their bismuth-rhodium analogues exhibit complementary reactivity and show great potential for small molecule and solvent activation chemistry. DFT calculations highlight the importance of metal-metal bonding interactions in controlling carbene electrophilicity. The paucity of these interactions between the 4d orbitals of rhodium and the 6p orbitals of bismuth results in weaker π-back-bonding interactions for bismuth-rhodium carbene complexes compared to dirhodium carbene complexes. This leads to weakening of the rhodium-carbene bond and to a more carbene-centered LUMO, accounting for the observed enhancement in bismuth-rhodium carbene electrophilicity. These findings are supported by a detailed spectroscopic study of the "donor-donor" carbene complexes Rh2(esp)2C(p-MeOPh)2 (19) and BiRh(esp)2C(p-MeOPh)2 (20), employing a combination of UV-vis and resonance Raman spectroscopy. The results reveal that carbene chemoselectivity in MRh(L)4 catalysis can be modulated to a previously unrecognized extent by the distal metalloligand.
A silver-catalyzed Büchner reaction
Lovely, Carl J.,Browning, R. Greg,Badarinarayana, Vivek,Dias, H.V. Rasika
, p. 2453 - 2455 (2007/10/03)
A silver scorpionate complex, derived from the highly fluorinated [HB(3,5-(CF3)2Pz)3]-, catalyzes the addition of ethyl diazoacetate to benzene rings, providing norcaradienes, which undergo electrocyclization to provide the corresponding cycloheptatriene. These reactions are surprisingly selective for addition to the aromatic moiety rather than C-H insertion.
