Group 12 metal zwitterionic thiolate compounds: preparation and structural characterization

Abstract

Reactions of TabHPF₆ (Tab = 4-(trimethylammonio)benzenethiolate) with three equiv. of M(OAc)₂·2H₂O (M = Zn, Cd) gave rise to two tetranuclear adamantane-like compounds, [M₄(μ-Tab)₆(Tab)₄](PF₆)₈·S (1·S: M = Zn, S = DMF·4H₂O; 2·S: M = Cd, S = DMF·5H₂O). The similar reactions of MCl₂ (M = Zn, Cd, Hg) with four equiv. of TabHPF₆ in the presence of Et₃N afforded three mononuclear compounds [M(Tab)₄](PF₆)₂·S (3·S: M = Zn, S = 2(H₂O)_0.5; 4·S: M = Cd, S = 2(H₂O)_0.5; 5·S: M = Hg, S = 2DMF). Treatment of the precursor complex 3 or 5 with equimolar MCl₂ and two equiv. of TabHPF₆ and Et₃N produced one dinuclear compounds [M(μ-Tab)(Tab)₂]₂(PF₆)₄·2DMF·2H₂O (6·2DMF·2H₂O: M = Zn; 8·2DMF·2H₂O: M = Hg) while analogous reactions of 4 with CdCl₂·2H₂O gave rise to [Cd(μ-Tab)₂(Tab)]₂(PF₆)₄·2DMF (7·2DMF). These compounds were characterized by elemental analysis, IR spectra, UV-Vis spectra, ¹H NMR and single-crystal X-ray crystallography. In 1 or 2, four M²⁺ ions and six S atoms of Tab ligands constitute an adamantane-like [M₄(μ-S)₆] cage in which each M²⁺ ion is tetrahedrally coordinated by one terminal S and three bridged S atoms from four different Tab ligands. In 3–5, each M²⁺ center of the [M(Tab)₄]²⁺ dication is tetrahedrally coordinated by four S atoms of Tab ligand. Two [M(Tab)₂]²⁺ dications in 6 or 8 are further bridged by a pair of Tab ligands to form a dimeric [M(μ-Tab)(Tab)₂]₂⁴⁺ structure. Each dimeric [(Tab)Cd(μ-Tab)₂Cd(Tab)]⁴⁺ unit in 7 is linked to its two neighboring units via two couples of bridging Tab ligands, thereby generating a unique 1D cationic chain. These results may provide useful information on interpreting structural data of MTs containing group 12 metals.