Germylenes, ambiphilic Ge(II)-complexes that bear an empty p-orbital and a Ge-centred lone pair, have attracted significant attention as promising tools in main-group catalysis due to their unique electronic structure and reactivity patterns. Much like N-heterocyclic carbenes (NHCs) form a substantial subclass within the lightest of the tetrylenes, N-heterocyclic germylenes (NHGes) represent a similarly significant subclass of germylenes, distinguished by analogous bonding and electronic features. The ring-systems of these NHGes exhibit different degrees of unsaturation and ring-size, spanning from 4-to 7-membered motifs. Additionally, decoration of the N-donor with bulky substituents results in kinetic stabilisation of the reactive Ge(II) centre. The reactivity of these centres is largely due to the reduced state of Ge(II), where the Ge(II/IV) redox couple facilitates the activation of bonds like C-H and H-H via oxidative addition (Scheme 1, a). This allows Ge(II) to exhibit reactivity patterns that closely parallel those of transition metals (TMs). Redox-neutral bond activation can also take place through Ge-ligand cooperativity. In these cases the bonds are activated ditopically over the Ge(II) centre and the ligand backbone, retaining the divalent state on Ge. Some examples of this type of reactivity feature ylide-like Ge-complexes bearing diketiminate (NacNac) ligands or Ge-complexes ligated by iminopyridines, allowing for the activation of a plethora of bonds (Scheme 1, b). The ambiphilic nature of germylenes also renders them excellent ligands for transition metals, with examples spanning the whole d-block. The versatility of the potential Ge-M manifolds that can be synthesised also translates to a versatility in the loci of reactivity. The reactivity of these systems can either be localised on one of the two components of the Ge-M manifold, or be ditopic and spread over both components (Scheme 1, c). In an interesting example by Cui et al., a bis-germylene was synthesised bearing a redox-active naphthyridine diimine ligand, which could act as donor of up to six electrons. Redox-active ligands (RALs) can act as electron reservoirs, storing electrons and eliminating the need to access energetically unfavourable oxidation states at the bound metal centre. This results in a flattening of the energy landscape of chemical transformations, with the metals acting as a conduit for the electrons. A compelling example is the reported four-electron reactivity of a iminopyridine-germylene complex, where the Ge(II) centre is oxidised to Ge(IV) while also acting as conduit for the electrons stored in the RAL. This electronic flexibility of RALs has also been leveraged in main group complexes to impart bond activation reactivity typically associated with transition metals. For example, a bis-Al(II) complex bound to redox-active diimine ligands can mediate the four-electron cleavage of the N=N bond in azo-compounds, with the electrons required being provided by both oxidation of the Al(II) centres and the RALs. This promising avenue has led to the isolation of a multitude of RAL-based complexes of main group metals such as Mg, Al, Ga, Si, , and Ge. In contrast to the well-reported cooperative reactivity of germylene-TM complexes, examples reporting cooperative transformations such as ditopic bond activation or synergistic redox activity have, to the best of our knowledge, not been extended to germylene-main group combinations. We hypothesised that the naphthyridine diimine scaffold would enable us to integrate the previously described strategies within a single, versatile germylene scaffold. Instead of introducing two Ge(II) centres in the dinucleating naphthyridine scaffold, introduction of only one Ge(II) centre would leave a vacant redox-active pocket for a or main group metal (or TM) to bind in close proximity to the germylene and potentially facilitate the envisioned cooperative reactivity (Scheme 1, d). Here we report the synthesis, characterisation and electronic structure of such an NHGe. We describe the binding of Zn and Mg to the vacant site and detail the electronic structures of these heterodinuclear complexes, focussing on the interaction between the Ge(II) centre with the metal in close proximity. Lastly, we detail the activation of substrates containing C-C multiple bonds by the Ge-Mg complex, where the Mg centre plays a vital role in electronically stabilising a quadruply reduced ligand, whilst Ge engages in metal-ligand cooperative activation of C-C unsaturated bonds.