Three-Fold-Symmetric Selenium-Donor Metallaboratranes of Cobalt and Nickel.

A novel selenium-containing pyridazinyl-based soft scorpionate ligand (KTnse) was synthesized. It reacts with CoCl and NiCl, yielding the first metallaboratrane complexes with selenium in their donor positions. Further substitution with Ag(OTf) or NaN allows isolation of the respective triflate or azide complexes.