Metal–metal bonded alkaline-earth distannyls. Issue 20 (23rd April 2021)

• Record Type: Journal Article
• Authors: Chapple, Peter M.; Cartron, Julien; Hamdoun, Ghanem; Kahlal, Samia; Cordier, Marie; Oulyadi, Hassan; Carpentier, Jean-François; Saillard, Jean-Yves; Sarazin, Yann
• Is Part Of: Chemical science. Volume 12:Issue 20(2021)
• Page Start: 7098
• Page End: 7114
• Publication Date: 2021-04-23
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d1sc00436k
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : The complete series of heterobimetallic alkaline-earth distannyls [Ae{SnR3 }2 ·(thf) x ] (Ae = Ca, Sr, Ba) have been prepared for R = Ph and SiMe3, and their bonding and electronic properties have been comprehensively investigated. Abstract : The first families of alkaline-earth stannylides [Ae(SnPh3 )2 ·(thf) x ] (Ae = Ca, x = 3, 1 ; Sr, x = 3, 2 ; Ba, x = 4, 3 ) and [Ae{Sn(SiMe3 )3 }2 ·(thf) x ] (Ae = Ca, x = 4, 4 ; Sr, x = 4, 5 ; Ba, x = 4, 6 ), where Ae is a large alkaline earth with direct Ae–Sn bonds, are presented. All complexes have been characterised by high-resolution solution NMR spectroscopy, including 119 Sn NMR, and by X-ray diffraction crystallography. The molecular structures of [Ca(SnPh3 )2 ·(thf)4 ] (1′ ), [Sr(SnPh3 )2 ·(thf)4 ] (2′ ), [Ba(SnPh3 )2 ·(thf)5 ] (3′ ), 4, 5 and [Ba{Sn(SiMe3 )3 }2 ·(thf)5 ] (6′ ), most of which crystallised as higher thf solvates than their parents 1–6, were established by XRD analysis; the experimentally determined Sn–Ae–Sn′ angles lie in the range 158.10(3)–179.33(4)°. In a given series, the 119 Sn NMR chemical shifts are slightly deshielded upon descending group 2 from Ca to Ba, while the silyl-substituted stannyls are much more shielded than the phenyl ones ( δ 119 Sn/ppm: 1′, −133.4; 2′, −123.6; 3′, −95.5; 4, −856.8; 5, −848.2; 6′, −792.7). The bonding and electronic properties of these complexes were also analysed by DFT calculations. The combined spectroscopic, crystallographic and computational analysis of these complexes provide some insight into the main features of these unique families of homoleptic complexes. A comprehensive DFT study (Wiberg bond index, QTAIM and energy decomposition analysis) points at a primarily ionic Ae–Sn bonding, with a small covalent contribution, in these series of complexes; the Sn–Ae–Sn′ angle is associated with a flat energy potential surface around its minimum, consistent with the broad range of values determined by experimental and computational methods.