Direct Electrochemical Synthesis of Pyrimidine-2-thionato Complexes of Zinc(II) and Cadmium(II): The Crystal Structure of (1,10-Phenanthroline)bis(pyrimidine-2-thionato)cadmium(II)

Abstract

Zn(pymt)2 and Cd(pymt)2 complexes have been obtained by electrochemical oxidation o f anodic zinc or cadmium in acetonitrile solutions o f pyrimidine-2-thione (Hpymt). W hen 2,2'-bipyridine (bipy) or 1,10-phenanthroline (phen) was added to the electrochemical cell, the adducts [M (pymt)2(bipy)], or [M(pymt)2(phen)] (M = Zn or Cd) were obtained. Crystals o f [Cd(pymt)2phen] are orthorhombic, with a = 9.882(2), b = 12.491(1), c = 16.513(2)A, space group P 2,2,2, and Z = 4. The cadmium atom has distorted octahedral geometry, and one ni trogen atom o f each pyrimidine-2-thiolato ligand is not coordinated.

Electrochemical Synthesis and Structural Characterisation of Cadmium and Mercury Complexes Containing Pyrimidine‐2‐thionate Ligands

“…The Cd-N bond lengths of 2.336(4) and 2.457(4) Å are also close to the values found in other octahedral complexes of cadmium containing heterocyclic thionates as ligands; for example 2.42(2) and 2.53(2) Å in [Cd(pymS) 2 (phen)], [42] [Cd(4,6-CF 3 MepymS) 2 (bipy)] and [Cd(4,6-CF 3 PhpymS) 2 -(phen)] (see below).…”

“…[42,46] The Cd-N pymS bond lengths [2.56(2) Å and 2.570(4) Å for 4 and 6, respectively] are clearly longer than those involving the metal and the nitrogen atoms of the bipyridine in 4 or phenanthroline in 6 [Cd-N bipy = 2.38(3) Å and Cd-N phen = 2.378(4) Å]. This situation is probably due to the fact that the chelate coordination of the thionate ligand gives rise to a four-membered ring, which causes an elongation of the C-N bond as the interaction with sulfur is more favourable and the thionate ligand is rigid.…”

“…However, these Cd-N bipy and Cd-N phen bond lengths [2.38(3) Å] do not differ significantly from those found in other octahedral cadmium(ii) 2,2Ј-bipyridine and 1,10-phenanthroline complexes. [42,46] The thionate ring is nearly planar and the exocyclic sulfur atom is also in the same plane. Other structural characteristics of the thionate ligand and the 2,2Ј-bipyridine or 1,10-phenanthroline unit are as one would expect and do not warrant further discussion.…”

Synthesis and Structure of the Group 12 Pyrimidinethiolate Complexes ∞3[Zn(S‐2‐N2C4H3)2], ∞2[Cd(S‐2‐N2C4H3)2], [Hg(S‐2‐N2C4H3)2] and[Cd(S‐2‐N2C4H3)2(tmeda)]

“…These bands are interpreted as being due to C-H bending and C-S stretching vibrations in the neu-tral ligand. Interestingly, Kennedy et al have found that extensive coupling within the ring system, as indicated, for example, by an 18 O study of 2-hydroxypyridine, [25] precludes the identification of any band definitively assigned to a C-S stretching vibration. [21] Two peaks in the spectrum of pyrimidinethiol at 1051 and 983 cm -1 have been assigned as ring breathing vibrations.…”

“…[18] However, crystal structures have not been reported to date. Herein, the structures of [M(S-2-N 2 C 4 H 3 ) 2 ] n (M = Zn, Cd, Hg) are reported and the complexes synthesised by an organometallic approach.…”