Carbon-carbon couplings in the reactions of unsaturated Group 4 metal s-cis-butadiene complexes with 2,6-xylyl isocyanide

Abstract

Chemical Society, for support of this research. S. D. acknowledges a Rumble fellowship provided by Wayne State University for support of his graduate studies. Registry No. Trimesitylaluminum-tetrahydrofuran, 99654-Supplementary Material Available: Complete listings of bond lengths (Table SI), bond angles (Table S-11), anisotropic thermal parameters (Table S-III), and hydrogen atom positional coordinates and isotropic thermal parameters (Table S-IV) and a packing diagram (Figure S-1) (7 pages); a listing of observed and calculated structure factors (Table S-V) (23 pages). Ordering information is given on any current masthead page.

Synthesis and characterization of titanium tetraisocyanide complexes, [CpTi(CNXyl)4E], E=I, SnPh3, and SnMe3

“…Extensions of this study to alkyl isocyanides, the heavier group 4 elements, and analogous oxidations of [Cp * Ti(CO) 4 ] À [16] in the presence of CNXyl will be of significance to determine whether related group 4 isocyanide complexes are possible. Use of Cp * instead of Cp in the titanium chemistry is of particular interest because of a prior study by Teuben and co-workers which showed that the reaction of the quite labile diene complex ([Cp * Ti(diene)Cl], diene = 2, 3-dimethyl-1,3-butadiene), with CNXyl afforded a reductively coupled isocyanide complex, [(Cp * TiCl) 2 (l-{N(Xyl)-C} 2 )] [39], instead of one containing discrete isocyanide ligands, as in the case of 1. In particular, did the reductive coupling of CNXyl in Teuben's system arise due to the presence of the diene, the Cp * group, both ligands simultaneously, or other factors?…”

Modern applications of low-valent early transition metals in synthesis and catalysis

“…The result is a unique formal [4+1] coupling reaction alongside cleavage of an isocyanide triple bond, such that the C atom is inserted into both C-H bonds at the 2 position to give an exo-methylene. By contrast, the reaction with the hafnium analogue of 28 results in 31 , which was initially misidentified as a cyclic amidine complex 124 but instead is the result of imine C-C coupling from the Hf analogue of 29 . The Cp* 2 Zr analogue can selectively insert one equivalent of isocyanide (or CO) into the metal-butadiene bond, allowing for sequential reactions to be carried out 125 .…”

Five-membered metallacycles of titanium and zirconium ? attractive compounds for organometallic chemistry and catalysis

“…It is true that for the case of mononuclear compounds this type of complex was not described, but Hessen and co-workers published an interesting coupling of two isocyanides to a m-''trans''-diazabutatriene complex of the heterocumulene RNLCLCLNR, which is very similar to the already discussed m-''trans''-butatriene titanium complex. 31 In that paper the authors outlined the similarities to the coupling reaction of acetylides to 1,3-butadiynes and their complexation (Scheme 19).…”