A Tripodal Trisilanol Ligand and Its Complexation Behavior towards Cu super(I), Cu super(II), and Zn super(II)

• Published in: European journal of inorganic chemistry Vol. 2014; no. 12; pp. 2124 - 2130
• Main Authors: Schax, Fabian, Braun, Beatrice, Limberg, Christian
• Format: Journal Article
• Language: English
• Published: 01.04.2014
• Subjects: Complexation; Crystal structure; Equivalence; Hydrogen bonding; Ligands; NMR spectroscopy; Routing (telecommunications); X ray diffraction
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201400088

A three-step synthetic route for a new tripodal branched trisilanol ligand PhSi(OSiPh sub(2)OH) sub(3) (LH sub(3)) was developed. X-ray diffraction analysis revealed that the trisilanol crystallizes as a dimer with a cyclic hydrogen-bonding network. The reaction of LH sub(3) with three equivalents of Cu sub(n)es sub(n)(Mes = mesityl) led to a hexanuclear compound [L sub(2)Cu sub(6)] (1), which was characterized by single-crystal X-ray diffraction analysis as well as by solution NMR spectroscopy. The crystal structure of 1 revealed that the compound features a hexagonal planar Cu super(I) sub(6) ring, which is the first of its kind in an oxygen environment. Deprotonation of the ligand with n-butyllithium and subsequent reaction with CuBr sub(2) resulted in the dinuclear Cu super(II) complex [L' sub(2)Cu sub(2)][Li(THF sub(2))] sub(2) (2, THF = tetrahydrofuran), which contains a new siloxide ligand formed from L super(3-) by the elimination of a SiOPh sub(2) unit, as evidenced by X-ray diffraction analysis. To check if the "Ph sub(2)SiO" elimination is a general behavior of this trisilanol, the reaction with ZnBr sub(2) was investigated under analogous conditions. However, this led to the isolation of [L sub(2)Zn sub(2)][ Li(OEt)] sub(2) (3) without any rearrangement of the siloxide ligand. A tripodal branched trisilanol ligand PhSi(OSiPh sub(2)OH) sub(3) (LH sub(3)) was synthesized. Its reaction with three equivalents of Cu sub(n)es sub(n)(Mes = mesityl) led to a hexanuclear compound [L sub(2)Cu sub(6)] with a planar Cu super(I) sub(6) ring. Deprotonation of LH sub(3) with n-butyllithium and subsequent reaction with either CuBr sub(2) or ZnBr sub(2) resulted in dinuclear complexes. In the case of CuBr sub(2), the original ligand eliminates a "Ph sub(2)SiO" unit.