Reaction of at ethered triamine ligand with Bi-(NMe 2 ) 3 gives aBitriamide,for which aBi I electronic structure is shown to be most appropriate.T he T-shaped geometry at bismuth provides the first structural model for edge inversion in bismuthines and the only example of aplanar geometry for pnictogen triamides.A nalogous phosphorus compounds exhibit ad istorted pyramidal geometry because of different BiÀNa nd PÀNb ond polarities.A lthough considerable Bi I character is indicated for the title Bi triamide,i te xhibits reactivity similar to Bi III electrophiles,a nd expresses either avacant or afilled porbital at Bi, as evidenced by coordination of either pyridine N-oxideo rW (CO) 5 .T he product of the former shows evidence of coordination-induced oxidation state change at bismuth. Scheme 1. Synthesis of low-oxidation-state p-block complexes by either external reductants or redox-active ligands.

The use of pincer ligands to access non‐VSEPR geometries at main‐group centers is an emerging strategy for eliciting new stoichiometric and catalytic reactivity. As part of this effort, several different tridentate trianionic substituents have to date been employed at a range of different central elements, providing a patchwork dataset that precludes rigorous structure–function correlation. An analysis of periodic trends in structure (solid, solution, and computation), bonding, and reactivity based on systematic variation of the central element (P, As, Sb, or Bi) with retention of a single tridentate triamide substituent is reported herein. In this homologous series, the central element can adopt either a bent or planar geometry. The tendency to adopt planar geometries increases descending the group with the phosphorus triamide (1) and its arsenic congener (2) exhibiting bent conformations, and the antimony (3) and bismuth (4) analogues exhibiting a predominantly planar structure in solution. This trend has been rationalized using an energy decomposition analysis. A rare phase‐dependent dynamic covalent dimerization was observed for 3 and the associated thermodynamic parameters were established quantitatively. Planar geometries were found to engender lower LUMO energies and smaller band gaps than bent ones, resulting in different reactivity patterns. These results provide a benchmark dataset to guide further research in this rapidly emerging area.

Stable neutral and highly-reactive cationic Bi complexes featuring NNN and PNP pincer ligands are debuted.

The use of pincer ligands to access non-VSEPR geometries at main-groupc enters is an emerging strategy for elicitingn ew stoichiometric and catalytic reactivity.A sp art of this effort, severald ifferent tridentatet rianionic substituents have to dateb een employed at ar ange of different centrale lements, providing ap atchworkd ataset that precludes rigorouss tructure-function correlation.A na nalysis of periodic trendsi ns tructure (solid, solution, and computation), bonding, and reactivity based on systematic variation of the central element( P, As, Sb, or Bi)w ith retentiono fa single tridentate triamides ubstituent is reported herein. In this homologous series, the centrale lement can adopt either ab ent or planar geometry.T he tendency to adopt planarg eometries increases descending the group with the phosphorus triamide( 1)a nd its arsenic congener (2)e xhibiting bent conformations,a nd the antimony (3)a nd bismuth (4)a naloguese xhibiting ap redominantly planar structure in solution.T his trend has been rationalized using an energy decomposition analysis. Ar arep hase-dependent dynamic covalentd imerizationw as observed for 3 and the associated thermodynamic parameters were establishedq uantitatively. Planarg eometries were found to engender lower LUMO energiesa nd smaller band gaps than bent ones, resulting in different reactivity patterns.T hese results provide ab enchmark dataset to guidef urtherr esearchi nt his rapidlye merging area.

Reaction of a tethered triamine ligand with Bi(NMe2)3 gives a Bi triamide, for which a BiI electronic structure is shown to be most appropriate. The T‐shaped geometry at bismuth provides the first structural model for edge inversion in bismuthines and the only example of a planar geometry for pnictogen triamides. Analogous phosphorus compounds exhibit a distorted pyramidal geometry because of different Bi−N and P−N bond polarities. Although considerable BiI character is indicated for the title Bi triamide, it exhibits reactivity similar to BiIII electrophiles, and expresses either a vacant or a filled p orbital at Bi, as evidenced by coordination of either pyridine N‐oxide or W(CO)5. The product of the former shows evidence of coordination‐induced oxidation state change at bismuth.