Hypervalence in germanium compounds containing the tetracylic moiety {S(C6H3S)2O}Ge via O···Ge transannular interactions: A structural study

Treatment of RnGeCl4−n with {S(C6H3SH)2O} (1) afforded the stable phenoxathiin-4,6-dithiolate compounds [{S(C6H3S)2O}GeR2] [n = 2; R = Et (2), Ph (3)] and [{S(C6H3S)2O}GeRCl] [n = 1; R = Et (4), Ph (5)]. Treatment of GeCl4 with 1 in benzene afforded the dichloro compound [{S(C6H3S)2O}GeCl2] (8) at 7 °C. Bromo compounds [{S(C6H3S)2O}GeRBr] [R = Et (6), Ph (7)] and [{S(C6H3S)2O}GeBr2] (9) were synthesized by halogen exchange from the appropriate chloro derivative using KBr/HBr. X-ray structure determinations of diorganyl dithiolate compounds 2 and 3 revealed that germanium atom is contained in a boat–chair-shaped eight-membered central ring and displays a tetrahedral geometry. In contrast, compounds 4–6 display a boat–boat-shaped central ring with a significant intramolecular transannular O···Ge interaction. The geometry of the pentacoordinate Ge atom in these last complexes may be described as distorted trigonal bipyramidal with a 62–65% distortion displacement.

The synthesis of [{S(C6H3S)2O}GeRnHal2−n] compounds (R = Et, Ph; Hal = Cl, Br; n = 2–0) is described. The acidity of the GeRHal2+ fragment enhances a transannular O···Ge interaction, prompting a trigonal bipyramidal germanium local geometry; the GeR22+ less acid fragment present has an opposite effect.Figure optionsDownload as PowerPoint slide