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Open AccessArticle

(2-Pyridyloxy)silanes as Ligands in Transition Metal Coordination Chemistry

1
Institut für Anorganische Chemie, TU Bergakademie Freiberg, D-09596 Freiberg, Germany
2
Institut für Analytische Chemie, TU Bergakademie Freiberg, D-09596 Freiberg, Germany
*
Author to whom correspondence should be addressed.
Inorganics 2018, 6(4), 119; https://doi.org/10.3390/inorganics6040119
Received: 29 September 2018 / Revised: 24 October 2018 / Accepted: 26 October 2018 / Published: 31 October 2018
(This article belongs to the Special Issue Coordination Chemistry of Silicon)
Proceeding our initial studies of compounds with formally dative TM→Si bonds (TM = Ni, Pd, Pt), which feature a paddlewheel arrangement of four (N,S) or (N,N) bridging ligands around the TM–Si axis, the current study shows that the (N,O)-bidentate ligand 2-pyridyloxy (pyO) is also capable of bridging systems with TM→Si bonds (shown for TM = Pd, Cu). Reactions of MeSi(pyO)3 with [PdCl2(NCMe)2] and CuCl afforded the compounds MeSi(µ-pyO)4PdCl (1) and MeSi(µ-pyO)3CuCl (2), respectively. In the latter case, some crystals of the Cu(II) compound MeSi(µ-pyO)4CuCl (3) were obtained as a byproduct. Analogous reactions of Si(pyO)4, in the presence of HpyO, with [PdCl2(NCMe)2] and CuCl2, afforded the compounds [(HpyO)Si(µ-pyO)4PdCl]Cl (4), (HpyO)2Si[(µ-pyO)2PdCl2]2 (5), and (HpyO)2Si[(µ-pyO)2CuCl2]2 (6), respectively. Compounds 16 and the starting silanes MeSi(pyO)3 and Si(pyO)4 were characterized by single-crystal X-ray diffraction analyses and, with exception of the paramagnetic compounds 3 and 6, with NMR spectroscopy. Compound 2 features a pentacoordinate Si atom, the Si atoms of the other complexes are hexacoordinate. Whereas compounds 14 feature a TM→Si bond each, the Si atoms of compounds 5 and 6 are situated in an O6 coordination sphere, while the TMCl2 groups are coordinated to pyridine moieties in the periphery of the molecule. The TM–Si interatomic distances in compounds 14 are close to the sum of the covalent radii (1 and 4) or at least significantly shorter than the sum of the van-der-Waals radii (2 and 3). The latter indicates a noticeably weaker interaction for TM = Cu. For the series 1, 2, and 3, all of which feature the Me–Si motif trans-disposed to the TM→Si bond, the dependence of the TM→Si interaction on the nature of TM (Pd(II), Cu(I), and Cu(II)) was analyzed using quantum chemical calculations, that is, the natural localized molecular orbitals (NLMO) analyses, the non-covalent interaction (NCI) descriptor, Wiberg bond order (WBO), and topological characteristics of the bond critical points using the atoms in molecules (AIM) approach. View Full-Text
Keywords: AIM; DFT; intermetallic bond; 29Si NMR spectroscopy; X-ray diffraction AIM; DFT; intermetallic bond; 29Si NMR spectroscopy; X-ray diffraction
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MDPI and ACS Style

Ehrlich, L.; Gericke, R.; Brendler, E.; Wagler, J. (2-Pyridyloxy)silanes as Ligands in Transition Metal Coordination Chemistry. Inorganics 2018, 6, 119.

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