Reactions of Nitridotechnetium(V) Complexes with Boranes

Nitrido bridges between technetium and boron were formed during reactions of [TcN(PMe2Ph)(Et2dtc)2] (Et2dtc− = diethyldithiocarbamate) and BH3 or BPhCl2 at low temperatures. X-Ray structure determinations show that the products contain almost linear Tc–N–B bonds with Tc–N distances which are only slightly lengthened with respect to the triple bonds in the precursor molecule. However, a significant lengthening of the Tc–S bond trans to the nitrido ligand is detected by the decrease of the structural trans influence of “N3−”N. The compounds are instable and decompose at room temperature under cleavage of the N–B bonds. A reaction between [TcNCl2(PPh3)2] and BCl3 does not yield a product with a nitrido bridge. Prolonged heating in dichloromethane results in decomposition of the technetium complex and the formation of (HPPh3)2[TcCl6]. Hydrogen bonds are established between the complex anion and each two counter ions.