The characterisation of 1,1-diphenylstannacyclopentane and 1,1,6,6-tetraphenyl-1,6-distannacyclodecane. An X-ray diffraction study of the distannacyclodecane

Abstract

The first oligomeric stannacycloalkane, 1,1,6,6-tetraphenyl-1,6-distannacyclodecane (A) has been isolated, together with the monomer, 1,1-diphenylstannacyclopentane (B), from the reaction between butane-1,4-diyl- [graphic omitted] dimagnesium dibromide and diphenyltin dichloride. These compounds have been characterised by molecular weight measurements and by i.r., mass, ¹³C, and ¹¹⁹Sn n.m.r. spectroscopy. In (A), the ¹³C n.m.r. signal of C-3 shows two pairs of satellites from coupling to the two tin nuclei, ²J 19.4 and ³J 38.0 Hz. In (B), the ¹³C signal of C-3 shows one pair of satellites, ^2/3J 19.6 Hz, which can be regarded as resulting from the algebraic sum of the two-bond and three-bond mediated couplings. The structure of the distannacyclodecane (A) has been determined by single-crystal X-ray diffraction. It has a boat-chair-boat structure, similar to that of cyclodecane itself, with the Ph₂Sn groups replacing those methylene groups which are not subject to steric hindrance. The principal features of the structure of the stannacyclopentane (B) are apparent from a preliminary X-ray study. It has a twisted conformation of C₂ symmetry, with a twist angle of ca. 15° and an endocyclic angle at tin of 95°.