Preparation and structure of rhenium fluoride trioxide ReO3F, and the polymorphism of rhenium trifluoride dioxide, ReO2F3

The methods of preparation of ReO3F are revised. ReO3F is an amorphous yellow solid that crystallizes into colorless needles after prolonged heating. Its structure is that of a fluorine and oxygen bridged chain with hexa coordinated rhenium atoms (a = 670.9(2), b = 596.6(2), c = 1030.6(4) pm, beta = 90.057(7)degrees, space group P2/c. In presence of donor solvents ReO(3)F(.)2L (L = (C2H5)(2)O, (CH3)(2)O, THF) are formed. ReO2F3, if crystallized from HF, exists in two crystalline forms, both are fluorine bridged chain polymers. (ReO2F3-I: a = 1539.7(3), b = 999.6(3), c = 924.4(2) pm, beta = 95.25(1)degrees, space group P2(1)/c; ReO2F3-II: a = 544.9(1), b = 494.2(1), c = 1253.7(2) pm, beta = 98.543(7)degrees, space group P2(1)/c. ReO2F3 crystallizes from CFCl3 Or SO2FCl as fluorine bridged cyclic trimer (a = 881.4(4), c = 822.1(6) pm, gamma = 120 degrees, space group P6(3)/m, or fluorine bridged cyclic tetramer (a = 1107.8(2), b 999.4(2), c = 1347.9(3) pm, space group Cmca).