DINUCLEAR AND TETRANUCLEAR CAGES OF OXODIPHENYLANTIMONY PHOSPHINATES - SYNTHESIS AND STRUCTURES

The novel dimeric compounds [Ph(2)Sb(O(2)PR(2))O](2) . 2CH(2)Cl(2) [R = cycl-C6H11 (2) and cycl-C8H15 (3)] have been synthesized by reacting diphenylantimony trichloride (1) with 3 mol equiv of silver acetate f ollowed by 1 mel equiv of the phosphinic acid. By the same route under more stringent conditions to exclude moisture, the mixed phosphinate- acetate [Ph(2)Sb(O2P(C6H11)(2))(O(2)CMe)]O-2 (4) was isolated and char acterized. Treatment of 2 with acetic acid/water affords the tetranucl ear cage Ph(8)Sb(4)O(4)(OH)(2) (O2P(C6H11)(2))(2) . CH3COOH . CH2Cl2 ( 5); it is possible to convert 5 to 2 by heating it with an excess of t he phosphinic acid. Compounds 2, 3, and 5 have been characterized by X -ray structural analysis. All of them possess four membered Sb2O2 ring s with hexacoordinated antimony. In 5 the antimony atoms in the two Sb 2O2 rings are connected by oxo bridges on two sides to give an Sb4O6 c age. These structures are correlated with those of known tin cages.