TY - JOUR
T1 - Cp2ti(κ2 -tbuncntbu)
T2 - A complex with an unusual κ2 coordination mode of a heterocumulene featuring a free carbene
AU - Beaumier, Evan P.
AU - Gordon, Christopher P.
AU - Harkins, Robin P.
AU - Mcgreal, Meghan E.
AU - Wen, Xuelan
AU - Copéret, Christophe
AU - Goodpaster, Jason D.
AU - Tonks, Ian A.
N1 - Publisher Copyright:
© 2020 American Chemical Society
PY - 2020/4/29
Y1 - 2020/4/29
N2 - Although there are myriad binding modes of heterocumulenes to metal centers, the monometallic κ2-ECE (E = O, S, NR) coordination mode has not been reported. Herein, the synthesis, isolation, and physical characterization of Cp2Ti(κ2-tBuNCNtBu) (3) (Cp = cyclopentadienyl, tBu = tert-butyl), a strained 4-membered metallacycle bearing a free carbene, is described. Computational (DFT, CASSCF, QT-AIM, ELF) and solid-state CP-MAS 13C NMR spectroscopic analysis indicate that 3 is best described as a free carbene with partial Ti-Cβ 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 3 corroborate its carbene-like nature: protonation with [LutH]I results in the formation of a Ti-formamidinate (4), while oxidation with S8 yields a Ti-thioureate (5). Additionally, a related bridged dititanamidocarbene, (Cp2Ti)2(μ- η 1, η 1-CyNCNCy) (10) (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.
AB - Although there are myriad binding modes of heterocumulenes to metal centers, the monometallic κ2-ECE (E = O, S, NR) coordination mode has not been reported. Herein, the synthesis, isolation, and physical characterization of Cp2Ti(κ2-tBuNCNtBu) (3) (Cp = cyclopentadienyl, tBu = tert-butyl), a strained 4-membered metallacycle bearing a free carbene, is described. Computational (DFT, CASSCF, QT-AIM, ELF) and solid-state CP-MAS 13C NMR spectroscopic analysis indicate that 3 is best described as a free carbene with partial Ti-Cβ 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 3 corroborate its carbene-like nature: protonation with [LutH]I results in the formation of a Ti-formamidinate (4), while oxidation with S8 yields a Ti-thioureate (5). Additionally, a related bridged dititanamidocarbene, (Cp2Ti)2(μ- η 1, η 1-CyNCNCy) (10) (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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U2 - 10.1021/jacs.0c02487
DO - 10.1021/jacs.0c02487
M3 - Article
C2 - 32240590
AN - SCOPUS:85085141583
SN - 0002-7863
VL - 142
SP - 8006
EP - 8018
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 17
ER -