Hypervalence at tin(IV) by transannular bonding of sulfur in an eight-membered ring: The case of dibenzostannocines [{S(C_6H _4S)_2}Sn]

摘要

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; 1, 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.