A sandwich-type cluster containing Ge@Pd<sub>3</sub> planar fragment flanked by aromatic nonagermanide caps.

Xu, Hong-Lei; Tkachenko, Nikolay V; Wang, Zi-Chuan; Chen, Wei-Xing; Qiao, Lei; Muñoz-Castro, Alvaro; Boldyrev, Alexander I; Sun, Zhong-Ming · Nat Commun · 2020

basic_science · Level V

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Abstract

Sandwich-type clusters with the planar fragment containing a heterometallic sheet have remained elusive. In this work, we introduce the [K(2,2,2-crypt)]<sub>4</sub>{(Ge<sub>9</sub>)<sub>2</sub>[η<sup>6</sup>-Ge(PdPPh<sub>3</sub>)<sub>3</sub>]} complex that contains a heterometallic sandwich fragment. The title compound is structurally characterized by means of single-crystal X-ray diffraction, which reveals the presence of an unusual heteroatomic metal planar fragment Ge@Pd<sub>3</sub>. The planar fragment contains a rare formal zerovalent germanium core and a peculiar bonding mode of sp<sup>2</sup>-Ge@(PdPPh<sub>3</sub>)<sub>3</sub> trigonal planar structure, whereas the nonagermanide fragments act as capping ligands. The chemical bonding pattern of the planar fragment consists of three 2c-2e Pd-Ge σ-bonds attaching Pd atoms to the core Ge atom, while the binding between the planar fragment and the aromatic Ge<sub>9</sub> ligands is provided by six 2c-2e Pd-Ge σ-bonds and two delocalized 4c-2e σ-bonds. The synthesized cluster represents a rare example of a sandwich compound with the heteroatomic metal planar fragment and inorganic aromatic capping ligands.