Hydrogen scrambling processes in [Ta(η-C5Me5)(η-C5H5){(µ-H)2BH2}]: a surprising observation
Abstract
Quantitative phase-sensitive two-dimensional exchange n.m.r. spectra of [Ta(η-C5Me5)(η-C5H5)-{(µ-H)2BH2}] show that the observed scrambling of the terminal and bridging hydrogens of the (µ-H)2BH2 ligand proceeds by a dominant mechanism in which there is no direct exchange between the two terminal hydrogens. This has been interpreted in terms of an associative mechanism proceeding via an Ta{(µ-H)3BH} intermediate accompanied by η5↔η3 shifts of the C5 rings.