Synthesis of a T‐Shaped Cobalt(I) Complex and Its Dinitrogen Adduct

The coordination chemistry of the new NNP pincer ligand framework (QuiNacNacP) is explored with cobalt. Upon treatment of the cobalt(II) complex Co[QuiNacNacP]Cl with KC8, the formation of cobalt(I) dinitrogen complex Co[QuiNacNacP]N2 was observed. Co[QuiNacNacP]N2 crystallizes as a square planar (S = 0) complex with an essentially unactivated N2 ligand. In solution, the dinitrogen complex is in equilibrium with the paramagnetic T‐shaped complex Co[QuiNacNacP] (S = 1). The ability of Co[QuiNacNacP]Cl to act as a catalyst precursor in the reductive silylation of dinitrogen was also briefly explored. Reaction of ≈ 1000 equivalents KC8 with ≈ 1500 equivalents Me3SiCl (relative to Co[QuiNacNacP]Cl) under 1 atm of N2 furnished roughly 40 equivalents of N(SiMe3)3. A new quinolone‐based pincer ligand was developed, and its coordination chemistry with CoII was examined. Upon reduction, a square‐planar dinitrogen cobalt(I) derivative is formed, which is in equilibrium with a T‐shaped complex. A preliminary study shows that this system is capable of catalytically silylating dinitrogen.