Crystal and electronic structures of Ni(II) silanethiolates containing flexible diamine ligands

• One mononuclear and four coordination polymers containing silanethiolate residue have been synthesized.
• Single-crystal structure of three complexes have been determined.
• Thermal stability and spectral properties of synthesized complexes have been described.
• The spin Hamiltonian parameters g, D, and E were determined for mononuclear compound using high-field HF EPR spectra.

Five nickel(II) complexes containing aliphatic diamines and tri-tert-butoxysilanethiolate ligand have been synthesized for the purpose of studying their structural, spectral (IR, UV–Vis, HF EPR) and thermal properties. Complexes (1)–(5) have been prepared in high yield by reactions of [Ni{SSi(OtBu)3}2(NH3)(H2O)] with 1.3-propanediamine (L1), 1,6-hexanediamine (L2), or 1,7-heptanediamine (L3). The X-ray structures were determined for complexes [Ni{(SSi(OtBu)3}2(μ-L1)2] (1), [Ni{(SSi(OtBu)3}2(μ-L2)2]n (2) and [Ni{(SSi(OtBu)3}2(μ-L3)4]n (3). Compound (1) is mononuclear with Ni(II) ions coordinated by two molecules of chelating 1.3-diaminepropane. Complexes (2) and (3) consist of 1D polymeric structures with Ni(II) atoms bridged by diamine molecules. The coordinated atoms and the nickel atom form a NiN2S2 square-planar core in polymeric (2) and a distorted trans-octahedral NiN4S2 core in mononuclear (1) and polynuclear (3). Reactions of [Ni{SSi(OtBu)3}2(NH3)(H2O)] with 1,4-butanediamine (L4) and 1,5-pentanediamine (L5) resulted in single crystals of compounds (4) and (5) which were not suitable for X-ray measurements. The spin Hamiltonian parameters g, D, and E were determined for compound (1) from high-field HF EPR spectra.

Five new nickel silanethiolates with diamines have been obtained. X-ray crystallography and spectroscopic methods FT-IR, UV–Vis and HF EPR followed. Complexes (2) and (3) are 1D coordination polymers showing different topology. Thermal stability of (2)–(4) complexes studied with TG-DTG.Figure optionsDownload as PowerPoint slide