Formation of Separated versus Contact Ion Triplets in Magnesium Thiolates. Synthesis and Characterization of [Mg(15-crown-5)(SCPh3)2] and [Mg(15-crown-5)(THF)2][S-2,4,6-tBu3C6H2)]2

Abstract

The synthesis and structural characterization of two magnesium thiolate complexes are described. Both compounds were prepared by analogous reactions routes, namely, alkane elimination and transamination, but using differently sized ligands. Utilization of the smaller HSCPh₃, resulted in the formation of [Mg(15-crown-5)(SCPh₃)₂], 1, displaying a seven-coordinate magnesium center with two magnesium−sulfur bonds. Employment of the sterically more encumbered HS-2,4,6-tBu₃C₆H₂ yielded a separated cation and anions as displayed in [Mg(15-crown-5)(THF)₂][S-2,4,6-tBu₃C₆H₂]₂, 2. Compound 2 exhibits a seven-coordinate cation, completing its coordination environment with five metal−crown-ether interactions in addition to two tetrahydrofuran (THF) contacts. The compounds were characterized by IR and NMR spectroscopy in addition to X-ray crystallography. Crystal data with Mo Kα (λ = 0.710 73 Å) are as follows: 1, C₄₈H₅₀MgO₅S₂, a = 8.4785(4) Å, b = 9.3595(5) Å, c = 13.8306(6) Å, α = 87.332(1)°, β = 85.929(1)°, γ = 68.733(1)°, Z = 1, triclinic; 2, C₅₄H₉₄MgO₇S₂, a = 13.6755(2) Å, b = 12.8045(6) Å, c = 32.7127(12) Å, β = 97.87(1)°, Z = 4, monoclinic.