Direct measurement of covalent three-center, two-electron M-H-B bonding in Zr and Hf borohydrides using B K-edge XAS.

ABSTRACT: Metal borohydride complexes have long been the subject of intense fundamental interest because of their unconventional metal-ligand bonding that occurs via three-center, two-electron M-H-B bonds. This type of bonding implies significant delocalization of electron density over all three atoms, but the degree of orbital mixing between the metal and boron has been difficult to assess by direct experimental means. Herein, we demonstrate how ligand K-edge X-ray absorption spectroscopy (XAS) conducted at the B K-edge yields evidence of significant covalent M-H-B bonding with Zr and Hf. To accommodate the B K-edge XAS studies, which were conducted under ultra-high vacuum (<10^-8 torr), we prepared a series of new [Zr(RBH₃)₄] and [Hf(RBH₃)₄

SUBMITTER: Hansen HM 

PROVIDER: S-EPMC12570076 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature