Synthesis, characterization, and structural properties of mercury(II), cadmium(II) and zinc(II) tripiperidinophosphine chalcogenide complexes

Abstract

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.

Synthesis and structural characterization of Zn2+, Cd2+ and Hg2+ complexes with tripyrrolidinophosphine chalcogenides

“…and mercury (5 and 6) complexes are presumably due to better solubility of these complexes in dichloromethane and/or extensive dissociation in this solvent compared to cadmium complexes 3 and 4, consistent with our previous results on closely related complexes [21].…”

“…The smaller shifts of the selenides as compared to sulfides are consistent with the difference observed between P=O and P=S absorption upon coordination in related complexes [22,31] and are reasonable since the vibrations involving the relatively heavy sulfur or selenium atom would be less sensitive to coordination than those with the lighter oxygen atom. In contrast, the increase in the frequency of the P-N vibration range (909-1087 vs. 850-1080 cm -1 in the free ligands) suggests that the nitrogen atoms are not involved in coordination, in agreement with previously results observed in related systems [21].…”

“…In order to investigate the constitution of complexes 1-6 and see the effect of switching the ligand structure from Pip3PE [21] to the smaller Pyrr3PE on the stereochemistry of these complexes, the solid state structures of complexes 2-6 were analyzed. Unfortunately, attempts to obtain good quality crystals of complex 1 were unsuccessful.…”

“…We have previously shown that whilst piperidine containing bidentate ligands MeN(Pip2PE)2 (Pip = piperidinyl, E= S or Se) [20] form mononuclear complexes, analogous monodentate ligands, Pip3PE (Pip = piperidinyl, E = S or Se), produce dinuclear complexes [21]. More recently, we investigated the generality of this observation using the oxide analogue, Pip3PO, and showed that it forms mononuclear complexes [22], in contrast to dinuclear adducts obtained with its above mentioned sulfide and selenide counterparts, Pip3PE [21].…”

Low Molecular Weight Fluorescent Probes (LMFPs) to Detect the Group 12 Metal Triad

“…All three elements are found in the +2 oxidation state, they all adopt a range of coordination numbers (2,4, and 6 being the most common) and form tetrahedral and octahedral complexes [71]. Mercury is found predominantly in a linear (coordination 2) or tetrahedral (coordination 4) geometry [72,73]. The 3d sub-shell for zinc is somewhat polarizable, despite its high charge-to-volume ratio [74].…”