Hypervalence at tin(IV) by transannular bonding of sulfur in an eight-membered ring: The case of dibenzostannocines [{S(C 6H 4S) 2}Sn

Abstract

Treatment of Ph 2SnCl 2 with S(C 6H 4SH) 2 in benzene leaded to the formation of [{S(C 6H 4S) 2}SnPhCl] ( 1); the same reaction with 1,4-diazabicyclo-[2.2.2]-octane leaded [{S(C 6H 4S) 2}SnPh 2] ( 4). The compounds [{S(C 6H 4S) 2}SnPhHal] (Hal = Br, 2; I, 3) have been synthesized by halogen exchange from 1 and the corresponding potassium halide. The compound [{S(C 6H 4S) 2}SnCl 2] ( 5) was obtained from S(C 6H 4SH) 2 and SnCl 4. The reaction of 1 with NaS 2CNEt 2·3H 2O yielded [{S(C 6H 4S) 2}SnPh{S 2CNEt 2}] ( 6). X-ray structure determinations of dibenzostannocines 1– 6 revealed that the tin atom acts as an acceptor atom displaying an intramolecular transannular interaction with the sulfur (thioether-like) atom. The local geometry of the Sn atom in the compounds 1– 5 is described as distorted trigonal bipyramidal with a TBP character spanning from 81% to 73%. In 6 the tin atom is six-coordinate with a distorted octahedral geometry.