Ligand Effects on the Electronic Structure of Heteroleptic Antimony-centered Radicals.

We report on the structures of three unprecedented heteroleptic Sb-centered radicals L(Cl)GaSb R (2-R, R = B[N(Dip)CH]22-B, 2,6-Mes2C6H32-C, N(SiMe3)Dip 2-N) stabilized by one electropositive metal fragment [L(Cl)Ga] (L = HC[C(Me)N(Dip)]2, Dip = 2,6-i-Pr2C6H3) and one bulky B- (2-B), C- (2-C), or N-based (2-N) substituent. Compounds 2-R are predominantly metal-centered radicals. Their electronic properties are largely influenced by the electronic nature of the ligands R , and significant delocalization of unpaired spin density onto the ligands was observed in 2-B and 2-N. Cyclic voltammetry (CV) studies showed that 2-B undergoes a quasi-reversible one-electron reduction, which was confirmed by the synthesis of [K([2.2.2]crypt)][L(Cl)GaSbB[N(Dip)CH]2] ([K([2.2.2]crypt)][2-B]) containing the stibanyl anion [2-B]-, which was shown to possess significant Sb-B multiple bonding character.