[(Tpt-Bu,Me)Yb(μ-H)]2: a fecund precursor to a host of divalent, hydrotris(pyrazolyl)borate supported f-element complexes

We present an overview of recent work from our laboratories on the chemistry of the divalent lanthanide hydride [(Tpt-Bu,Me)Yb(μ-H)]2 (1). The first section deals with the hydrotris(3-tert-butyl, 5-methyl-pyrazolyl)borate, (Tpt-Bu,Me), ligated divalent lanthanide complexes leading up to the discovery of 1. The remaining sections are centered on the divalent ytterbium hydride [(Tpt-Bu,Me)Yb(μ-H)]2 (1), its preparation, molecular structure, NMR characteristics and reactivity. Three broad reactivity classes will be described, namely reactions with Lewis bases and Lewis acids, such as the perfluoroaryl boranes, σ-bond metathesis reactions generally involving acidic HX bonds, but also an example of CSi bond cleavage, and insertion chemistry, primarily involving alkynes. The molecular structures of several representative complexes have been determined by X-ray crystallography.