Photoreductive Elimination of PhCl Across the Dinuclear Core of a [GePt]VI Complex

Diverse Functionality of Molecular Germanium: Emerging Opportunities as Catalysts

Fundamental research on germanium as the central element in compounds for bond activation chemistry and catalysis has achieved significant feats over the last two decades. Designing strategies for small molecule activations and the ultimate catalysts established capitalize on the orbital modalities of germanium, apparently imitating the transition-metal frontier orbitals. There is a growing body of examples in contemporary research implicating the tunability of the frontier orbitals through avant-garde approaches such as geometric constrained empowered reactivity, bimetallic orbital complementarity, cooperative reactivity, etc. The goal of this Perspective is to provide readers with an overview of the emerging opportunities in the field of germanium-based catalysis by perceiving the underlying key principles. This will help to convert the discrete set of findings into a more systematic vision for catalyst designs. Critical exposition on the germanium's frontier orbitals participations evokes the key challenges involved in innovative catalyst designs, wherein viewpoints are provided. We close by addressing the forward-looking directions for germanium-based catalytic manifold development. We hope that this Perspective will be motivational for applied research on germanium as a constituent of pragmatic catalysts.

σ-GeH and Germyl Cationic Pt(II) Complexes

The low electron count Pt(II) complexes [Pt(NHC')(NHC)][BAr^F] (where NHC is a N-heterocyclic carbene ligand and NHC' its metalated form) react with tertiary hydrogermanes HGeR₃ at room temperature to generate the 14-electron platinum(II) germyl derivatives [Pt(GeR₃)(NHC)₂][BAr^F]. Low-temperature NMR studies allowed us to detect and characterize spectroscopically some of the σ-GeH intermediates [Pt(η²-HGeR₃)(NHC')(NHC)][BAr^F] that evolve into the platinum-germyl species. One of these compounds has been characterized by X-ray diffraction studies, and the interaction of the H-Ge bond with the platinum center has been analyzed in detail by computational methods, which suggest that the main contribution is the donation of the H-Ge to a σ*(Pt-C) orbital, but backdonation from the platinum to the σ*(Ge-H) orbital is significant. Primary and secondary hydrogermanes also produce the corresponding platinum-germyl complexes, a result that contrasts with the reactivity observed with primary silanes, in which carbon-silicon bond-forming reactions have been reported. According to density functional theory calculations, the formation of Pt-Ge/C-H bonds is both kinetically and thermodynamically preferred over the competitive reaction pathway leading to Pt-H/C-Ge bonds.