COMPOUNDS OF GERANIUM AND TIN, 25 - A ZWITTERIONIC DISTANNENE AND 2 (RSNX)(4) CAGES WITH AN UNUSUAL ARRANGEMENT OF THE SN4X4 CLUSTER ATOMS (R = TBU(3)SI, X = SE, TE)

Reaction of tin(II) chloride with RNa(THF)(2) (R = tBu(3)Si) in THF at -30 degrees C led to a complex reaction mixture, from which the compo unds R4Sn4(THF)(2), R2SnSnR2 (5), R-R (7), and a brownish black compou nd 6 were isolated. In toluene as solvent, the zwitterionic distannene 5 was obtained together with 7 and 6 which upon treatment with Et3PX, furnished the cluster compounds (RSnX)(4) (10: X = Se; 11: X = Te). T he Xray structure analyses of the isotypic compounds 10 and 11 reveale d that the tin atoms occupy the corners of an undistorted tetrahedron with weak tin-tin interactions. The chalcogen atoms form a plane which bisects the Sn, tetrahedron.