Mixed-metal phosphinito complexes of platinum(II) and palladium(II) with lanthanide and actinide elements. The single-crystal X-ray structure of [UO2(OH2){(OPPh2)2Pd(S2CNEt2)}2]

Abstract

The synthesis of the phosphinito-bridged heteronuclear complexes [M′{(OPPh₂)₂M(S₂CNR₂)}_n](M′= Ce^III, Eu^III, Sm^III, or Nd^III, n= 3; M′= Th^IV, n= 4) and [UO₂(OH₂){(OPPh₂)₂M(S₂CNR₂)}₂] by reaction of [M(S₂ CNR₂){(Ph₂PO)₂H}](M = Pd or Pt, R = Et or Prⁱ) with lanthanide and actinide salts is described. [UO₂(OH₂){(OPPh₂)₂ Pd (S₂CNEt₂)}₂] crystallises in the monoclinic space group C2/c with a= 26.285(8), b= 13.870(8), c= 21.068(6)Å, β= 90.042(8)°, and Z= 4. The single-crystal X-ray structure of the complex shows a distorted pentagonal bipyramidal uranium(VI) ion lying on a crystallographic two-fold axis with the oxo ligands of the trans-UO₂ moiety, UO = 1.774(7)Å, occupying apical sites. The structure confirms co-ordination of two [(OPPh₂)₂Pd(S₂CNEt₂)]^– moieties around U^VI. The four phosphinito ligands bridge U^VI and the two Pd^II centres with U–O = 2.289(7) and 2.342(6)Å and Pd–P = 2.2642(24) and 2.2455(23)Å. An aqua ligand, U–O = 2.526(8)Å, completes the co-ordination sphere around the uranyl centre. The Pd^II centres are essentially planar, each being bound to two phosphinito and one bidentate dithiocarbamate ligand, Pd–S = 2.386(3) and 2.373(3)Å.