Synthesis and initial transition metal chemistry of the first PGeP pincer-type germylene

Abstract

A PGeP pincer-type germylene, Ge(NCHPBu)CH, which contains two phosphane groups hanging from the N atoms of an N-heterocyclic germylene fragment, has been isolated for the first time. This compound has already furnished a rich transition metal derivative chemistry (Co, Rh, and Pd) that includes complexes containing bridging P,Ge,P-, chelating P,Ge- and pincer P,Ge,P-ligands.

From a Diphosphanegermylene to Nickel, Palladium, and Platinum Complexes Containing Germyl PGeP Pincer Ligands

“…The molecular structures of 2 Pd , 2 Pt , and 3 Ni were determined by X‐ray diffraction (XRD). The Supporting Information contains a large collection of bond lengths (Table S2) and a selection of interatomic bond angles (Table S3) for all the XRD‐determined structures reported in this article.…”

“…The Supporting Information contains a large collection of bond lengths (Table S2) and a selection of interatomic bond angles (Table S3) for all the XRD‐determined structures reported in this article. Compounds 2 Pd and 2 Pt (Figure ) are nearly identical in their metrical data (a short selection of interatomic distances is given in Table ), contain an almost tetrahedral Ge atom, with M−Ge bond lengths of 2.2777(3) Å ( 2 Pd ) and 2.3017(5) Å ( 2 Pt ), and have their M atom in a very distorted square‐planar environment (M1−P av =2.38 ( 2 Pd ), 2.34 Å ( 2 Pt ); M1−Cl1=2.3946(7) ( 2 Pd ), 2.388(1) Å ( 2 Pt )), the P1‐M1‐P2 angles being 149.36(3) o in 2 Pd and 154.02(4) o in 2 Pt owing to the strain imposed by the short CH 2 P t Bu 2 arms of their germyl PGeP pincer ligand. The metal atoms of 2 Pd and 2 Pt are rather well shielded by the tert ‐butyl groups of the phosphane fragment (Figure S23 in the Supporting Information).…”

“…However, transition‐metal complexes equipped with pincer‐type ligands containing at least a heavier tetrylene as a donor group (E) are still very scarce and, prior to our recent entry in this field, these ligands were restricted to the Driess’ ECE ( A ) and ENE ( B ) pincers shown in Figure , in which the tetrylene groups are donor‐stabilized benzamidinatosilylenes or ‐germylenes.…”

“…In a recent communication, we briefly described the synthesis and isolation (as a metal‐free product) of the first PEP pincer‐type heavier tetrylene, namely, the N‐heterocyclic germylene Ge(NCH 2 P t Bu 2 ) 2 C 6 H 4 ( 1 ; Figure ), as well as its reactions with a few transition‐metal complexes (Co 0 , Rh I , and Pd II ). Those initial reactivity studies suggested that germylene 1 is prone to increase the coordination number of its germanium atom through insertion processes that afford bridging germylene or terminal chloridogermyl PGeP pincer ligands .…”

“…In a recent communication, we briefly described the synthesis and isolation (as a metal‐free product) of the first PEP pincer‐type heavier tetrylene, namely, the N‐heterocyclic germylene Ge(NCH 2 P t Bu 2 ) 2 C 6 H 4 ( 1 ; Figure ), as well as its reactions with a few transition‐metal complexes (Co 0 , Rh I , and Pd II ). Those initial reactivity studies suggested that germylene 1 is prone to increase the coordination number of its germanium atom through insertion processes that afford bridging germylene or terminal chloridogermyl PGeP pincer ligands . A few additional transition‐metal complexes containing a germyl PGeP pincer ligand are currently known (Scheme ) and some of them have been successfully involved in homogeneous catalytic processes, but they have not been prepared from a germylene but from a diphosphanegermane.…”