Reaction of metal chlorides (MCl2) with tripiperidinophosphine chalcogenides (Pip3PE) produces new dimer species (1)(2)(3)(4)(5)(6) of the formula [MCl2(Pip3PE)]2 (Pip = piperidinyl; E = S or Se; M = Hg, Cd or Zn). These coordination complexes were characterized by elemental analysis, IR, multinuclear ( 31 P, 113 Cd and 199 Hg) NMR spectroscopy and single crystal X-ray analysis. Compounds 1-6 exist as centrosymmetric homobimetallic dimers, [M(µ-Cl)Cl(Pip3PE)]2. Each dimer incorporates two µ2-chloro atoms and two terminal M-Cl bonds. The E atom of Pip3PE forms terminal M-E bonds {S; 2.305(11); Se: 2.412(6)-2.589(15) Å} and thus the geometry about each metal centre is distorted tetrahedral and the range of tetrahedral bond angles is 102.83(3) to 113.32(3) o . The P=Se bond lengths of 2.183(9)-2.205(2) Å in the selenide complexes are slightly elongated compared to those in the free ligands [2.1090(4) Å]. The results are discussed and compared with those obtained for related analogues.

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Six new complexes of zinc(II), cadmium(II) and mercury(II) chlorides with tripyrrolidinophosphine chalcogenides of the types [MCl2(Pyrr3PE)2] (M = Zn, E = S (1) or E = Se (2); M = Cd, E = S (3) or E = Se (4)) and [{HgCl(Pyrr3PE)}2(µ-Cl)2] (E = S (5) or Se (6)) have been prepared in yields of 66-92% by reaction of the ligands with metal chloride in ethanol and characterized by 1 H and 31 P NMR, IR, elemental analysis, conductivity, and single crystal X-ray diffraction analysis. The results show that the complexes are pseudo tetrahedral containing coordinated chloride atoms. Interestingly, the X-ray studies reveal that whilst the title ligands produce dinuclear complexes with mercury, their Cd and Zn complexes are mononuclear. The tetrahedral bond angles vary from 85.69(5)° to 126.25(4)° in the dinuclear complexes 5 and 6 and from 93.51(3) o to 117.38(3) o in mononuclear species 2-4.The P=E bond lengths are in the range 1.999(9)-2.198(2) Å. The coordination properties of the title ligands are discussed and compared to those obtained for their bulkier counterparts.