Carbenes As Catalysts for Transformations of Organometallic Iron Complexes

Compared with the enormous arsenal of catalysts used to produce organic compounds, complementary species that are able to mediate sophisticated organometallic transformations are virtually nonexistent. We found that stable N-heterocyclic carbenes (NHCs) can mediate unusual organometallic transformations in solution at room temperature. Depending on the choice of NHC initiator, stoichiometric or catalytic reactions of bis(cyclooctatetraene)iron [Fe(COT)_2] ensue. The stoichiometric reaction leads to the isolation of a previously unknown mixed-valent species, featuring distinct and directly bonded Fe(0) and Fe(I) centers. In the catalytic process, three iron atoms are fused to afford the tri-iron cluster Fe_3(COT)_3, which is a hydrocarbon analog of Dewar’s classic Fe_3(CO)_(12) complex. The key step in both of these processes is proposed to involve the NHC’s ability to induce metal–metal bond formation. These NHC-mediated reactions provide a foundation on which to develop future organometallic transformations that are catalyzed by organic species

Synthesis and reactivity of olefin metathesis catalysts bearing cyclic (alkyl) (amino) carbenes

All it's CAACed up to be! Cyclic (alkyl)(amino)carbenes (CAACs) can be used as ligands for olefin metathesis catalysis. A dramatic steric effect of the N-aryl group of the CAAC on catalyst activity was observed and utilized to develop a new catalyst with activity comparable to standard commercially available catalysts

Insights Into the Carbene-Initiated Aggregation of [Fe(cot)_2]

Stable carbenes react with [Fe(cot)_2] in very different ways. Whereas the classical N-heterocyclic carbenes induce the formation of tetra- and trimetallic iron clusters, abnormal NHCs and carbocyclic carbenes (BACs) form mono- and bimetallic iron complexes. Cyclic (alkyl)(amino)carbenes (CAACs) react with [Fe(cot)_2] in a completely different manner, namely through outersphere [4+1] cycloaddition

Carbon–Carbon Bond Formation at a Neutral Terminal Carbido Ligand: Generation of Cyclopropenylidene and Vinylidene Complexes

No AbstractPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/55908/1/7422_ftp.pd