DIPHOSPHINOAMIDO COMPLEXES OF THORIUM(IV) AND URANIUM(IV) AND URANIUM(V) - CRYSTAL-STRUCTURES OF [(THCL2[N(CH2CH2PPR2I)(2)]2)2] AND [(UCL2[N(CH(2)CH(2)PET(2))2]2)2]

The complexes [MCl(x){N(CH(2)CH(2)PR(2))(2)}(4-x)] (M = Th or U; R = P t or Pr-i; x = 1-3) and [UCl2{N(CH2CH2 PPr2i)(2)}(3)] have been isolat ed in moderate to good yields from the reaction of MCl(4) with LI[N(CH (2)CH(2)PR(2))(2)]. The uranium(V) complex is shown to be formed by ad ventitious oxidation. The complexes isolated depend on the stoichiomet ry of the reaction, the bulk of the tertiary phosphine donors and the oxidation state of the metal (for uranium); they all have pendant dono rs and are labile in solution involving exchange of co-ordinated for u nco-ordinated tertiary phosphine. The solid-state structure of [ThCl2{ N(CH2CH2PPr2i)(2)}(2)] has been determined: triclinic, space group P $ ($) over bar$$ 1, a = 11.47(1), b = 13.18(1), c = 15.08(4) Angstrom, a lpha = 103.98(4), beta = 96.01(5), gamma = 99.17(4)degrees. It is dime ric in the solid state with two bidentate PNP ligands, one bridging an d one terminal chloride per thorium. The geometry of the thorium centr es is shown to be distorted capped octahedral. The solid-state structu re of [UCl2{N(CH(2)CH(2)PEt(2))(2)}(2)] was also determined: monoclini c, space group P2(1)/a, a = 26.274(3), b = 10.782(4), c = 24.659(7) An gstrom, beta = 90.31(14). It is dimeric in the solid state. containing one tri- and one bi-dentate chelating PNP ligand, one bridging and on e terminal chloride per uranium centre. The geometry of the uranium ce ntres is shown to be distorted dodecahedral.