Hypercoordination by Multiple Dangling Benzylmethoxy Ligands in Highly Crowded Triaryltin Bromide [(2‐MeOCH2C6H4)]3SnBr and Diaryltin Mixed Halides [(2‐MeOCH2C6H4)]2SnBrCl, and a related Distannane and Distannoxane

Abstract

AbstractThe reaction between the Grignard reagent formed from Mg and 2‐bromobenzylmethyl ether and SnCl4 produced four products: [2‐(MeOCH2)C6H4]3SnBr (1), [2‐(MeOCH2)C6H4]2SnX2 (2, X2=Br2 (a) and BrCl (b)), [{2‐(MeOCH2)C6H4}3Sn]2 (3), and [{2‐(MeOCH2)C6H4}2SnBr]2O (4). In the case of 1, two of the three dangling arm O atoms coordinate to the central tin atom with O−Sn internuclear distances of 2.53 (O1) and 2.91 (O2) Å, the shorter interaction being trans to the Br atom, the other trans to a phenyl carbon atom. In the case of 2a the resulting hexacoordinate structure exhibits two very short O−Sn interactions of 2.42 and 2.50 Å, well below the sum of the VdW radii of O and Sn, 3.69 Å. The sterically crowded ditin compound 3 was obtained in trace amounts and the structure demonstrates no dangling O−Sn interactions. General changes in structure compared to other distannane systems are reflective of the great steric crowding. Distannoxane 4, has a Sn−O−Sn bond angle of 148.1(2)° which is larger compared to other distannoxane structures. The intermolecular interactions between Sn−O 2.470(3) and 2.521(3)Å and 2.665(3) and 2.629(3)Å for Sn1 and Sn2 respectively are responsible for a distorted octahedral geometry around the two tin atoms. The various 119Sn, 13C and 1H NMR spectra are in accord with their structural analysis for 1 and 2, and in the solid state 13C NMR spectrum of 1 the dangling methylene group is observable whereas is solution there is a rapid dynamic equilibrium resulting in a single resonance for all methylene groups.