Recent Developments in the Chemistry of Pn(I) (Pn=N, P, As, Sb, Bi) Cations

Abstract

The Group 15 Pn(I) cations (Pn=N, P, As, Sb and Bi), which are isoelectronic with the donor‐stabilized carbones, have emerged recently. Despite the presence of two lone pair of electrons, the Pn(I) cations are weakly nucleophilic due to their inherent positive charge. Strongly electron‐donating supporting ligands including zwitterionic forms have been used to enhance their Lewis basicity. Furthermore, the chelating effect of cyclic ligand systems proved effective in increasing their nucleophilicity. The strategies involved in successfully isolating the fleeting Sb(I) and Bi(I) cations as the recent most achievements in this field have been discussed. The syntheses, structure, bonding situations and reactivity of the Pn(I) cations are discussed. An outlook on the periodic trends and future applications of these electronically unique electron‐rich cationic moieties have been provided.

Insertion of CO2and CS2into Bi–N bonds enables catalyzed CH-activation and light-induced bismuthinidene transfer

“…23,24 Similarly, the eld of cationic bismuth(I) compounds is virtually unexplored, with a single example of an isolable species 36 and the reactivity of these species being entirely unknown. 17,42 Along these lines, reactions of compounds 3-R demonstrate for the rst time that cationic bismuth compounds may be exploited both, for the light-driven construction of organic heterocycles and for photochemically-induced transfer of low-valent Bi(I) building blocks.…”

Chemistry of the Bis(imine)‐Based Tetradentate Ligand Stabilized Group 14 E(II) Cations (E=Ge and Sn)

“…The bis(phosphine) stabilized Sb(I) cation showed mono‐metallation with the coinage metals Cu(I), Ag(I) and Au(I) centers, despite the presence of two lone pair of electrons. However, this chemistry has been discussed elsewhere [37] and is beyond the purview of discussion in this account.…”

Stabilizing Monoatomic Two-Coordinate Bismuth(I) and Bismuth(II) Using a Redox Noninnocent Bis(germylene) Ligand

“…Compounds containing heavy p-block group 14 and 15 elements E in uncommon low oxidation states are of paramount interest because they provide multiple new opportunities for the design of main-group element species mimicking transition-metal-like reactivity with respect to small molecule activation and catalysis. − However, the synthesis of such isolable species is challenging and requires suitable ligation around the low-valent E atom to prevent E–E bond oligomerization and disproportionation. Recent developments in this direction have paved the way to zerovalent monatomic complexes of the group 14 elements named tetrylones with the general formula L:→E 0 ←:L (E = C, Si, Ge, Sn, Pb). − Utilizing the bis­(silylene)­xanthene, we achieved the whole series of heavier tetrylones previously. ,,, The central E 0 atom is two-coordinated by two sufficient donor ligands and obeys the octet rule, retaining its four valence electrons as two lone pairs. , The various tetrylones stabilized by sufficient Lewis bases show an unparalleled reactivity toward small molecules. − Monovalent group 15 element complex cations of the type L 2 E + (L = donor, E = N, P, As, Sb, Bi) − are known isoelectronic species but particularly difficult to tame for the heaviest pnictogen, bismuth. Compared with the lighter congeners, low-valent bismuth compounds possess exceptional features such as strong spin–orbit coupling (SOC) due to relativistic effects, , low redox potentials and transition-metal-like properties in redox catalysis. − It should be noted here that the peculiar electronic features of low-valent Bi play also a decisive role in rare earth metal–bismuth coordination compounds that are single-molecule magnets. − …”