“…As well as tricyclic silatranes, bicyclic silocanes are highly promising biologically active products [1]. Several molecular structures already have been determined by X-ray diffraction: X = Y = Ph, R = H (II) [2], X = Y = Ph, R = Me (III), X = Y = Ph, R = CMe 3 (IV), X = Y = Me, R = Ph (V), X = Y = Ph, R = Ph (VI) [3], X = Y = F, R = H (VII) [4], X = F, Y = Ph, R = Me (VIII) [5], X = F, Y = Me, R = H (IX) [6] major part of the determined silocane structures [II,III,VIII,IX] have a boat-boat (BB) configuration of eight-membered heterocycles Si-(OCC) 2 -N while structures IV and VII have boat-chair configurations of the skeleton. In all these structures the short SiÁ Á ÁN contact (with the exception of IV) is observed which vary within the 1.98-2.30 Å range thus indicating a N ?…”