SYNTHESIS AND COMPLEXATION OF DITHIATETRA ZADIBOROCINES

(Dialkylamino)dichloroboranes R2NBCl2 react with NN-bis-(trimethylsily l)-sulfur diimide to give a novel class of compounds, the eight-member ed rings bda4,5lambda4,2,4,6,8,3,7-dithiatetrazadiborocines (1). The d erivates with R = n-propyl (1a), isopropyl (1b), and n-butyl (1c) have been synthesized and characterized. The X-ray structure analysis of 1 b shows the molecule to have a boat-like configuration with two N=S = N functions connected via the BNR2 groups. Although the B atoms are li nked to three N atoms, only the exocyclic nitrogen is engaged in n bon d interactions with the boron. 1b reacts with W(CO)5(THF) to form the dinuclear complex 2, which is also investigated by means of an X-ray s tructure analysis. One W(CO)5 fragment is coordinated to a nitrogen at om of one N=S=N unit. whereas another W(CO)5 group is linked to the S atom of second SN2 function. However, the original sulfur diimide has changed into a sulfur diamide group HN-S-NH. A similar change of a N=S =N unit happens on treatment of 1b with Cp(CO)3WH leading to 3. As the X-ray structure analysis shows, in 3 again one sulfur diimide group r etains its original character. The second SN, unit has turned into a s ulfur amide function, where one N atom binds the H atom of (P(CO)3WH, the other one is linked to one of the CO ligands to form a carbonyl br idge between N and W. Among a series of other complexes only TiCl4 has additionally been found to react with 1b to yield 1b . 2 TiCl4, the s tructure of which is still unknown.