Andrew C. Price

Bis(diphenylphosphino)methane complexes of rhodium(III) halides as synthons for dinuclear rhodium(III) complexes

Several rhodium(II1) complexes have been synthesized by the reaction of dirhodium tetraacetate, Rh,(O,CCH,),, with bis(dipheny1phosphino)methane (dppm), in the presence of trimethylsilyl halides. Octahedral complexes of formula RhC13(dppm)(CH3CN) (1) and Rh13(dppm)(CH3CN) (2) have been isolated as minor products in the reaction between Rh,(OC for 2: space group Cc, a = 11.897(2), b= 17.110(3), c= 15.246(l) A, p= 106.04(g)“, V=2983(1) A3, Z=4; for 3: space group p2,2,21, a = 15.914(4), b = 19.819(6), c= 12.207(3) A, I’=3850(2) A3, 2=4.

Crystallographic disorder of the Re2 unit in complexes of the type A2Re2X8 (A=HP-n-Pr3, PMePh3; XCl or Br)

Abstract The preparation and structural characterization of three complexes containing the [Re2X8]2− (X=Cl or Br) anion are described. Crystallographic parameters are as follows: for [HPnPr3]2Re2Cl8 (1) a=33.831(9), b=11.274(6), c=18.286(5) A, β=91.11(1)°, V=6955(7) A3, Z=8, space group C2/c; for [PMePh3]2Re2Cl8 (2) a=10.861(2), b=11.964(3), c=16.235(4) A, β=93.40(2)°, V=2106(1), Z=2, space group P21/n; for [PMePh3]2Re2Br8 (3) a=10.964(2), b=12.198(2), c=16.421(2) A, β=93.83(1)°, V=2191(1) A3, Z=2, space group P21/n. These complexes exhibit an unusual form of crystallographic disorder which has been previously observed in other derivatives that contain the [Re2X8]2− anion. It is suggested that while this type of disorder must correlate with the positions of the cations relative to the anions in the crystal packing, and other factors, no simple analysis is likely to be adequate.