Tri- tert-butoxysilanethiolate complexes of manganese(II) with chelating heterocyclic bases – Structure of compounds with a MnN 2O 2S 2 or MnN 2OS 2 kernel and MeOH within the coordination sphere

Abstract

The reaction of labile bis(tri- tert-butoxysilanethiolato)tetra(methanol)manganese(II) [Mn{SSi(OBu t ) 3} 2(MeOH) 4] ( 1) with chelating heterocyclic bases (bipyridine, phenanthroline and neocuproine) resulted in the formation of new heteroleptic manganese(II) tri- tert-butoxysilanethiolate complexes exhibiting remarkable stability. Elemental and spectral analyses (IR, MS, UV–Vis) suggested that in all three cases two silanethiolate ligands and a heterocyclic base are attached to the metal centre giving complexes with [Mn{SSi(OBu t ) 3} 2(N–N)] stoichiometry, where N–N = 2,2′-bipyridine ( 2), 1,10-phenanthroline ( 3) and neocuproine ( 4). As a result of recrystallization from methanol monocrystals of 2 and a new, unstable complex [Mn{SSi(OBu t ) 3} 2(phen)(MeOH)] ( 3a) were formed and their structures determined. Both complexes are monometallic. The manganese atom in 2 is hexa-coordinated and the central MnN 2O 2S 2 kernel results from the O,S-chelating ability of the tri- tert-butoxysilanethiolate ligand. Compound 3a represents another type of complex, where the same silanethiolate ligand is bonded to manganese only through a sulfur atom, and a methanol molecule is present within the metal coordination sphere. The structure type found in 3a is characterized by a penta-coordinated Mn centre, a MnN 2OS 2 kernel, and the presence of three different ligands was previously unknown among manganese compounds. Compound 3a represents an extremely rare example of a metal thiolate complex, where an alcohol molecule serves as a coligand. Furthermore, it is the first ever obtained thiolate complex where N-, O- and S-donor atoms are derived from independent ligands.