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Article Abstract
Although there are myriad binding modes of heterocumulenes to metal centers, the monometallic κ-ECE (E = O, S, NR) coordination mode has not been reported. Herein, the synthesis, isolation, and physical characterization of CpTi(κ-BuNCNBu) () (Cp = cyclopentadienyl, Bu = -butyl), a strained 4-membered metallacycle bearing a free carbene, is described. Computational (DFT, CASSCF, QT-AIM, ELF) and solid-state CP-MAS C NMR spectroscopic analysis indicate that is best described as a free carbene with partial Ti-C bonding that results from Ti-N π-bonding mixing with N-C-N σ-bonding of the bent N-C-N framework. Reactivity studies of corroborate its carbene-like nature: protonation with [LutH]I results in the formation of a Ti-formamidinate (), while oxidation with S yields a Ti-thioureate (). Additionally, a related bridged dititanamidocarbene, (CpTi)(μ-η,η-CyNCNCy) () (Cy = cyclohexyl) is reported. Taken together, this work suggests that the 2-electron reduction of heterocumulene moieties can allow access to unusual free carbene coordination geometries given the proper stabilizing coordination environment from the reducing transition metal fragment.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7201867 | PMC |
| http://dx.doi.org/10.1021/jacs.0c02487 | DOI Listing |
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