Structural studies of some heterocyclic and organometallic compounds

Abstract

Single crystal X-ray work was carried out for four heterocyclic compounds: prior to this, definitive structures could not be written for any of these. The heterocyclic compounds reported are: 5,6-dihydro-1-thiobenzoylmethylene-1H-thiazolo[2,3-c][1,2,4] thiadiazole, (I); 4-N-(4'-bromophenylamino)-3-butylfuroxan, (II); 4,4'-methylenebis(1,3,5-trimethyl-4-imidazolin-2-one), (III), and 4-phenyl-3-phenylamino-1,2,4-thiadiazoline-5-one, (IV). These are then discussed, along with work which has been carried out for similar compounds. Trithiapentalenes and analogues having linear multisulphur systems are mentioned as criteria for deciding whether the NSS skeleton in (I) is best considered as N-S...S or N-S-S. Following this, the X-ray structure determinations of bis(4-methylpyridine)hydrogen(I) tetraphenylborate, (V), and bis(triphenylarsineoxide)hydrogen(I) tetrafluoroborate, (VI), arereported. Both (V) and (VI) are bis-cations which have strong hydrogen bonding. Other compounds with short 0...H...0 and N...H...N distances are mentioned, stabilities of such bis-cations compared to those of the monocations, and (amine-halogen-amine)⁺ complexes discussed. The final two X-ray structure determinations are for the compounds 1,1,1,3,3,3-hexaphenyldisilazane and µ-nitrido-bis (triphenylphosphorus)((I) thiocyanate. MNDO was used to calculate force constants for bending of linear molecular pseudohalides. The aim of such work was to rationalise 'unusual' geometries in some silicon-containing compounds via Second Order Jahn-Teller distortions, postulating that such compounds are easily distorted along a "soft' normal vibration coordinate.