Synthese und Komplexierung von Dithiatetrazadiborocinen

Synthesis and Complexation of Dithiatetrazadiborocines (Dialkylamino)dichloroboranes R 2 NBCl 2 react with N,N' ‐bis‐(trimethylsilyl)sulfur diimide to give a novel class of compounds, the eight‐membered rings 3,7‐bis(dialkylamino)‐ 3H,7H ‐1λ 4 ,5λ 4 ,2,4,6,8,3,7‐dithiatetrazadiborocines ( 1 ). The derivates with R = n ‐propyl ( 1a ), isopropyl ( 1b ), and n ‐butyl ( 1c ) have been synthesized and characterized. The X‐ray structure analysis of 1b shows the molecule to have a boat‐like configuration with two NSN functions connected via the BNR 2 groups. Although the B atoms are linked to three N atoms, only the exocyclic nitrogen is engaged in π bond 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 structure analysis. One W(CO) 5 fragment is coordinated to a nitrogen atom of one NSN unit, whereas another W(CO) 5 group is linked to the S atom of the second SN 2 function. However, the original sulfur diimide has changed into a sulfur diamide group HN–S–NH. A similar change of a NSN unit happens on treatment of 1b with Cp(CO) 3 WH leading to 3 . As the X‐ray structure analysis shows, in 3 again one sulfur diimide group retains its original character. The second SN 2 unit has turned into a sulfur amide function, where one N atom binds the H atom of Cp(CO) 3 WH, the other one is linked to one of the CO ligands to form a carbonyl bridge between N and W. Among a series of other complexes only TiCl 4 has additionally been found to react with 1b to yield 1b · 2 TiCl 4 , the structure of which is still unknown.