Phosphorus and Arsenic Atom Transfer to Isocyanides to Form π‐Backbonding Cyanophosphide and Cyanoarsenide Titanium Complexes

Decarbonylation along with E atom transfer from Na(OCE) (E=P, As) to an isocyanide coordinated to the tetrahedral Ti II complex [(Tp t Bu,Me )TiCl], yielded the [(Tp t Bu,Me )Ti(η 3 ‐ECNAd)] species (Ad=1‐adamantyl, Tp t Bu,Me− =hydrotris(3‐ tert ‐butyl‐5‐methylpyrazol‐1‐yl)borate). In the case of E=P, the cyanophosphide ligand displays nucleophilic reactivity toward Al(CH 3 ) 3 ; moreover, its bent geometry hints to a reduced Ad−NCP 3− resonance contributor. The analogous and rarer mono‐substituted cyanoarsenide ligand, Ad−NCAs 3− , shows the same unprecedented coordination mode but with shortening of the N=C bond. As opposed to Ti II , V II fails to promote P atom transfer to AdNC, yielding instead [(Tp t Bu,Me )V(OCP)(CNAd)]. Theoretical studies revealed the rare ECNAd moieties to be stabilized by π‐backbonding interactions with the former Ti II ion, and their assembly to most likely involve a concerted E atom transfer between Ti‐bound OCE − to AdNC ligands when studying the reaction coordinate for E=P.