Ancillary Ligand‐Controlled Dinitrogen Cleavage and Transformation at Titanium Centers

Abstract

ABSTRACT The activation and transformation of dinitrogen (N 2 ) represents a significant scientific challenge. In particular, while metal nitrides are pivotal intermediates, achieving N─N bond cleavage with 3d metals such as titanium remains scarce. Here we report unprecedented ancillary ligand control over the N 2 activation pathway in PCP‐ligated (PCP = 2,6‐( t Bu 2 PCH 2 ) 2 ‐C 6 H 3 ) titanium complexes upon reduction, wherein aryloxide or diarylamide groups facilitate complete N─N bond scission to dititanium bis( μ ‐nitrido) complexes, whereas the phenyl analogue leads to C─P bond activation of the pincer. Computational studies suggest that heteroatom‐mediated interactions with K + ions in the secondary coordination sphere facilitate isomerization of the N 2 bridge from end‐on to side‐on, thereby promoting N─N bond rupture. Moreover, these complexes catalyze the silylation of N 2 , producing up to 22.0 equiv. of N(SiMe 3 ) 3 , representing the highest turnover number (TON) for Group IV metal systems to date. These findings highlight the role of ligand environment in N 2 activation and provide new insights into the design of efficient early‐metal catalysts for nitrogen fixation.