Inorganic Chemistry, Vol.56, No.5, 2801-2811, 2017
Effect of a kappa(1)-Bonded-M-1,2,3-triazole (M = Co, Ru) on the Structure and Reactivity of Group 6 Alkoxy (Fischer) Carbenes
The [3 + 2] cycloaddition of two different metal-bound azides, [(Me(4)cyclam)Co-II(N-3)]ClO4 and (eta(5)-C5H5) (dppe)Ru-II(N-3), (dppe = Ph2P CH2CH2PPh2) with Cr(0) and W(0) (ethoxy)(alkynyl) Fischer carbenes has been efficiently used for the preparation of polymetallic metal-carbene complexes. The presence of the kappa(1)-bonded metal triazole causes a significant influence on the electronic properties, structure, and reactivity of this new class of Fischer alkoxycarbenes. For the Ru(II) derivatives, their chemical behavior is considerably influenced by the interaction of the (eta(5)-C5H5)(dppe)Ru-II-triazole moiety with the empty p-carbene orbital that provokes a noticeable decrease in the electrophilicity of the M=C carbon (manifested by the shielding of the C-13 NMR chemical shifts). In turn, in the Co(II) derivatives, the incorporation of the (Me(4)cyclam)Co-II moiety diminishes the aromaticity of the triazole ring and has a marked effect on the energy and distribution of the LUSO orbital, mostly resident on the Co(II) fragment. The almost negligible participation of the carbene moiety in the LUSO makes this position unable to react with nucleophiles. The reactions reported in this work constitute the first examples of [3 + 2] cycloaddition of azides and alkynyl Fischer carbene complexes in solution.