Als erstes Beispiel eines Tetrasilabicyclo[l.l.O]butan‐Derivats wird die Titelverbindung (VI) wie aufgezeigt ausgehend von Trichlorsilan (I) dargestellt.

The weak central Si‐Si bond in 1 is surprisingly short (2.373 Å)—its length is almost the same as that of the SiSi bonds in trans,trans,trans‐(tBuMeSi)4 (2.377 Å). The Si1Si3 bond was expected to be particularly long owing to the high p‐character and in analogy to the bonding in bicyclobutanes.

4-Trithiadiazepine(1) and its benzo derivative (2) have planar delocalised lox and 14n aromatic structures, respectively; in the dihydro compound (3) the five heteroatoms are co-planar, with the approximately cis and trans periplanar methylene protons rapidly interconverting.An X-ray analysis of dimethyl 1,3,5,2,4-trithiadiazepine-6,7dicarboxylate revealed a planar geometry for the heterocyclic ring.1 The parent trithiadiazepine (1) and its benzo (2) and dihydro (3) derivatives have been synthesised2 and their X-ray crystallographic structures are now reported? together with the results of ab initio3a and MND03b calculations and the photoelectron spectra of ( 1) and (2).Trithiadiazepines ( 1) and (2) (Figures 1 and 2) both have the

Reaction of tetrasul p hu rtetran itride with t ridtrip henyl phosp hi ne) plati nu m (0) or tetra kis( trip henylphosphine)palladium(O) gives [M(S2N2)(PPh3)I2-CH2Cl2; the X-ray structure of the platinum compound shows the [Pt(S2N2)I2 unit to be planar: the S2N22-group acts as a bidentate and bridging ligand with the platinum atoms bring bridged by nitrogen to form a four membered Pt2N2 ring.

Tetrasulphur tetranitride and phenyl vinyl sulphoxide or sulphone react to give a novel planar delocalised 1 4 ~~ electron aromatic system, 1 h462,3,5,7h462-tetrathia-2,4,6,8-tetraza-azulene (4) in which all the S4N4 atoms have been retained; the molecules form parallel overlapping stacks with a minimum interplanar atomic separation of 3.26 A.