Tuning the Inorganic Core of a reduced Ni 2 Ge 2 Cluster.

Tetranuclear cores (M-E) 2 of transition metals (M) and tetrylenes (E II =Si, Ge, Sn) are key motifs in homogeneous and heterogeneous catalysis. They exhibit a continuum of M-M and E-E bonding within the inorganic core that leads to a variety of structures for which there are no specific synthetic methods. Herein, we report a series of highly reduced [Ni 0 Ge II ] 2 squares solely stabilized by bulky terphenyl (C 6 H 3 -2,6-Ar 2 ) ligands, for which we provide complementary and high-yielding syntheses. Reactivity studies with common Lewis bases (carbene and CO) evince that the structure of the (M-E) 2 core can be transformed. We have investigated this core modification by computational means, offering a rationale to better understand the continuum of bonding across these clusters.