Formation, crystal and molecular structures of heteroleptic zinc(II) tri-tert-butoxysilanethiolates with ZnNO2S2 and ZnN2S2 coordination pattern

Five zinc tri-tert-butoxysilanethiolates containing heterocyclic, aromatic bases coordinated to zinc ion were synthesized. All obtained complexes are monomeric with ZnS2NO2 or ZnS2N2 core and formula: Zn(SSi(OBut)3)2L, where L is α-picoline (pic), 2,4-lutidine (lut) or N-methylimidazole (meim) or Zn(SSi(OBut)3)2L2 where L is pyridine (py) or N-methylimidazole. The complexes are formed in the two-stage synthesis. First zinc acetyloacetonate Zn(acac)2 reacts with tri-tert-butoxysilanethiol with the formation of [Zn{μ-SSi(OBut)3}(acac)]2 [B. Becker, A. Dołęga, A. Konitz, W. Wojnowski, Polyhedron 20 (2001) 949]. Subsequent addition of heterocycle leads to decomposition of [Zn{μ-SSi(OBut)3}(acac)]2 and complexes Zn(SSi(OBut)3)2L or Zn(SSi(OBut)3)2L2 are formed. Crystal structure determinations of the obtained complexes reveal distorted tetrahedral (Zn(SSi(OBut)3)2L2) or bipyramidal (Zn(SSi(OBut)3)2L) coordination of zinc atom. In the case of Zn(SSi(OBut)3)2L the immediate environment of zinc atom consists of two thiolate sulfur atoms, aromatic nitrogen and two oxygen atoms from tert-butoxy groups of tri-tert-butoxysilanethiolate completing coordination sphere.