On the Nature of Bonding in Synthetic Charged Molecular Alloy [P(7)ZnP(7)](4–) Cluster and Its Relevant [P(7)](3–) Zintl Ion

[Image: see text] Charged molecular alloys and Zintl ions are of interest in synthetic chemistry. However, their chemical bonding has seldom been elucidated using modern quantum chemistry tools. Herein, we report on in-depth chemical bonding analyses for a charged molecular alloy C(2) [P(7)ZnP(7)](4–) cluster and its relevant Zintl ion C(3v) [P(7)](3–) ligand, making use of electronic structure calculations at PBE0/def2-TZVP level, natural bond orbital and orbital composition analyses, canonical molecular orbitals, and adaptive natural density partitioning (AdNDP). The computational data show that C(3v) [P(7)](3–) Zintl ion has three isolated, negatively charged, bridging P sites. Such charges are largely P 3p lone-pairs in nature, but they also participate in secondary P–P bonding along the bridging sites. C(2) [P(7)ZnP(7)](4–) cluster is formulated as [P(7)](2–)[Zn](0)[P(7)](2–), in which [P(7)](2–) ligands maintain the structural and bonding integrity of [P(7)](3–) Zintl ion despite their difference in charge state. Two [P(7)](2–) ligands collectively bind with Zn center via four bridging P sites, resulting in a quasi-tetrahedral ZnP(4) core with the eight-electron counting. This bonding picture can alternatively be rationalized using the superatom concept. The Zn–P bonds are weak with a bond order of around 0.5, because the P centers have partial nonbonding 3p character, akin to 3p(2) lone-pairs albeit with a lower occupation number.