Triphenylantimony(v) catecholates and o-amidophenolates:: Reversible binding of molecular oxygen

Novel neutral antimony(v) complexes were isolated as crystalline materials and characterized by IR and NMR spectroscopy: o-amidophenolate complexes [4,6-di-tert-butyl-N-(2,6-dimethylphenyl)-o-amidophenolato]tri- phenylantimony(v) (Ph3Sb[AP-Me], 1) and [4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-amidophenolato]triphenyl- antimony(v) (Ph3Sb[AP-iPr], 2); catecholate complexes (3,6-di-tert-butyl-4methoxycatecholato)triphenylantimo- ny(v) (Ph3Sb[(MeO)Cat], 3), its methanol solvate 3 center dot CH3OH (4); (3,6-di-tertbutyl-4,5-di-methoxycatecholato)triphe- nylantimony(v) (Ph3Sb[(MeO)(2)Cat], 5) and its acetonitrile solvate 5 center dot CH3CN (6). Complexes 1-7 were synthesized by oxidative addition of the corresponding o-iminobenzoquinones or o-benzoquinones to Ph3Sb. In the case of the phenanthrene-9,10-diolate (PhenCat) ligand, two different complexes were isolated: Ph3Sb[PhenCat] (7) and [Ph4Sb](+)[Ph2Sb(PhenCat)(2)](8). Complexes 7 and 8 were found to be in equilibrium in solution. Molecular structures of 2, 4, 6, and 8 were determined by X-ray crystallography. Complexes 1-7 reversibly bind molecular oxygen to yield Ph3Sb[L-Me]O-2 (9), Ph3Sb[L-iPr]O-2 (10), Ph3Sb[(MeO)L']O-2 (11), Ph3Sb[(MeO),L']O-2 (12) and Ph3Sb[PhenL']O-2 (13), which contain five-membered trioxastibolane species (where L is the O,O',N-coordinated derivative of a 1-hydroperoxy-6(N-aryl)-iminocyclohexa-2,4-dienol, and L' the O,O',O-coordinated derivative of 6-hydroperoxy-6-hydroxycyclohexa-2,4-dienone). Complexes 9-13 were characterized by IR and H-1 NMR spectroscopy and X-ray crystallography.