Silver(I) Sandwich Complexes of Oxa‐Crowned Derivatives of Dithiomaleonitrile

Abstract

AbstractThe coordination chemistry of the four oxa‐crowned derivatives of dithiomaleonitrile mn‐12S2O2, mn‐15S2O3, mn‐18S2O4, and mn‐21S2O5 as well as of the acyclic bis(methylthio)maleonitrile mn‐S2 with AgI was investigated by X ray structural and spectroscopic methods. The 2:1 complexes (ligand/AgI) [Ag(mn‐12S2O2)2]PF6, [1]PF6, [Ag(mn‐15S2O3)2]PF6, [2]PF6, and [Ag(mn‐S2)2]PF6, [6]PF6, and the 1:1 complexes [Ag(mn‐15S2O3)]ClO4, [3]ClO4, [Ag(mn‐18S2O4)]PF6, [4]PF6, and [Ag(mn‐21S2O5)]PF6 [5]PF6, were obtained with AgPF6 or AgClO4 in MeOH. The stoichiometry of the macrocyclic AgI complexes and the coordination mode of mn‐S2On+1 coronands (n = 1–4) is determined by the length of the macrocyclic oligoethylene chain. – The mn‐crown dithioethers mn‐12S2O2 and mn‐15S2O3 form with AgPF6 the new sandwich complexes [Ag(mn‐12S2O2)2]PF6, [1]PF6, and [Ag(mn‐15S2O3)2]PF6, [2]PF6. [1]PF6 crystallises in the triclinic space group P1. In the centrosymmetric cation [1]+ each mn‐12S2O2 ligand is coordinated to the AgI centre in an endo manner via both S atoms and one O atom. The distance of the second O atom of mn‐12S2O2 to AgI is somewhat longer than a normal Ag–Oether bond. The overall environment around AgI in [1]+ is that of a distorted cubic S4O4 set of donors. [2]PF6 crystallises in the monoclinic space group C2/c. In the centrosymmetric cation [2]+ silver(I) is planar‐coordinated by the four S atoms of both mn‐15S2O3 molecules. The six O atoms of both mn‐15S2O3 ligands show only long‐range interactions to the AgI ion. They surround AgI almost vertically to the planar S4 set of donors in a crown‐like manner. – The crystal structures of the 1:1 complexes [Ag(mn‐18S2O4)]PF6, [4]PF6, and [Ag(mn‐21S2O5)]PF6, [5]PF6, consist of linear chain polymers. [5]PF6 forms an N‐bridged chain polymer of endocyclic [Ag(mn‐21S2O5)]+ units with S1O4NNitrile coordination at the AgI centre. In the 2:1 complex [Ag(mn‐S2)2]PF6, [6]PF6, each mn‐S2 acts as a monodentate NNitrile donor. – 13C‐NMR studies in nitromethane solution confirm that the AgI ions in the complexes of the mn‐crown dithioethers remain coordinated. However, the AgI ion in complex of mn‐S2 is decoordinated.