Carbodicarbene σ/π-Donation Enables a Reactive Two-Coordinate Germanium(II) Dication.

All previously reported Ge(II) dications have remained chemically dormant, their reactivity confined to simple coinage metal coordination-a consequence of cationization-induced lone pair contraction that renders the Ge center inaccessible to substrates. We report that dual σ/π-donating carbodicarbene (CDC) ligands directly counteract this contraction, yielding [(CDC)2Ge][OTf]2 (4), the first two-coordinate Ge(II) dication to display broad reactivity beyond coinage metal coordination. Crystallographic and computational analysis reveal a delocalized 3c-4e C-Ge-C moiety and a less contracted Ge lone pair with retained Ge-centered LUMO, underpinning an unprecedented reactivity profile encompassing 1,1-oxidative addition, [1 + 4] cycloaddition, selenium insertion, and cooperative C-S bond activation. As a Ge-donor ligand, 4 coordinates to Rh, Ir, and Ag with donor strength comparable to that of IMes and forms geminal bimetallic complex 8, featuring a rare noncluster Ag-Ge-Ag three-center two-electron bonding motif. These results establish CDC-based low-coordination stabilization as a productive strategy for accessing structurally simple yet reactive main-group dications.