Tetra-Cationic Distibane Stabilized by Bis(α-iminopyridine) and Its Reactivity

İngilizce (OpenAlex)

The work establishes the salt of a tetra-cationic distibane, [L 2 Sb 2 ][CF 3 SO 3 ] 4 = [ 1 ] 2 [OTf] 4 (CF 3 SO 3 = OTf), stabilized by a bis(α-iminopyridine) ligand L, defying the Coulombic repulsion. The synthetic approach involved a dehydrocoupling reaction when a mixture of L and Sb(OTf) 3 in a 1:1 ratio was treated with Et 3 SiH/LiBEt 3 H as the hydride source. Compound [ 1 ] 2 [OTf] 4 was also achieved from [LSbCl][OTf] 2 as a precursor and using Et 3 SiH. Dissolution of [ 1 ] 2 [OTf] 4 in polar solvents unveiled the formation of the persistent L -stabilized dicationic Sb(II) radical monomer [ 1 ][OTf] 2, while the addition of Me 3 SiOTf regenerated the dimer in the salt [ 1 ] 2 [OTf] 4 . The homolytic cleavage of the Sb–Sb bond in [ 1 ] 2 4+ has manifested in exchange reactions between [ 1 ] 2 [OTf] 4 and Ph 2 Ch 2 (Ch = S, Se), giving [LSb(SPh)][OTf] 2 = [ 2 ][OTf] 2 and [LSb(SePh)][OTf] 2 = [ 3 ][OTf] 2, respectively, in acetonitrile. Reaction between [ 1 ] 2 [OTf] 4 and p -benzoquinone gave [L 2 Sb 2 (C 6 H 4 O 2 )][OTf] 4 = [ 4 ][OTf] 4 . An interesting oxygen atom insertion reaction occurred when [ 1 ] 2 [OTf] 4 was treated with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) to give [L 2 Sb 2 O][ OTf] 4 = [ 5 ][OTf] 4 . The oxo-bridged compound [ 5 ][OTf] 4 was also obtained from exposure of [ 1 ] 2 [OTf] 4 in open air. The strong Mn–Mn bond in [Mn 2 (CO) 10 ] could be cleaved by reacting with [ 1 ] 2 [OTf] 4 in the presence of pyridine to form [LSbMn(CO) 5 ][ OTf] 2 = [ 6 ][OTf] 2 . On the other hand, the reaction between [Co 2 (CO) 8 ] and [ 1 ] 2 [OTf] 4 gave the oxidative addition product [L 2 Sb 2 Co(CO) 3 ][OTf] 3 = [ 7 ][OTf] 3 . The compounds were characterized both in the solid and solution states. Computational studies gave a comprehensive understanding of the experimental findings.