NCN Chelated Organoantimony(III) and Organobismuth(III) Phosphinates and Phosphites: Synthesis, Structure and Reactivity

The reaction of the organoantimony and organobismuthoxides [LSbO] 2 ( 1 ) and [LBiO] 2 ( 2 ), where L = [2,6‐(Me 2 NCH 2 ) 2 C 6 H 3 ] – , with phenylphosphinic acid in a 1:4 molar ratio gave the molecular organoantimony and organobismuth phosphinates LM[OP(H)(O)(Ph)] 2 [M = Sb ( 3 ), Bi ( 4 )]. Similarly, the reaction of 1 and 2 with H 3 PO 3 gave the secondary phosphites LM[OP(H)(O)(OH)] 2 [M = Sb ( 5 ), Bi ( 6 )] or the fully deprotonated phosphite {LM[O 2 P(H)(O)]} 2 [M = Sb ( 7 ), Bi ( 8 )] depending on whether the molar ratio of the starting materials was 1:4 or 1:2. The syntheses of novel mixed phosphinate‐phosphite LSb[OP(H)(O)(OH)][OP(H)(O)(Ph)] ( 9 ), phosphonate‐phoshinate LSb[OP( t Bu)(O)(OH)][OP(H)(O)(Ph)] ( 10 ) and phosphonate‐phosphite LSb[OP( t Bu)(O)(OH)][OP(H)(O)(OH)] ( 11 ) compounds are also described. While the organoantimony compounds 3 , 5 and 7 are stable in solution, the organobismuth congeners showed only limited stability in solution and underwent a redox process involving to the reduction of the bismuth ions, and oxidation of the phosphorus ions from the +III to +V oxidation state. The reaction pathway associated with the redox process was studied with the system bismuth oxide 2 + Ph 2 P(O)(H), which gave compound LBi[OP(O)(Ph) 2 ] 2 ( 14 ) as a result of the oxidation of the phosphorus ion. All compounds were characterized by elemental analysis, 1 H, 13 C and 31 P NMR spectroscopy and IR spectroscopy. The solid‐state molecular structures of compounds 3 , 5a {LM[O 2 P(H)(O)][(HO) 2 P(H)(O)]} and 7 were determined by X‐ray diffraction.