Dynamic aspects of hypervalent compounds effected by the formation of three center‐four electron bond in heteroatoms

A Redox‐Confused Bismuth(I/III) Triamide with a T‐Shaped Planar Ground State

“…[15c] Interpretation of 2 as at ransition-state mimic (see TS in Scheme 1d)i mplies the presence of ap artially occupied 6p orbital at Bi perpendicular to the molecular plane. [23] Thus, 2 should exhibit ambiphilic behavior and coordinate both Lewis bases and Lewis acids.W hile combining 2 with 4-(N,Ndimethylamino)pyridine (DMAP), triethylamine,and arange of triarylphosphines showed no reaction, addition of the less bulky donor pyridine N-oxide yielded the adduct 4 (Scheme 3), which has been isolated and comprehensively characterized. Thes tructure of 4 (Figure 4, left) shows as quare-based pyramid geometry at each Bi atom, and arises from interaction of three Natoms (N1, N2, N3) and one Oatom with the metal (Bi1), and afifth interaction involving an itrogen atom (N6) from as econd equivalent of 2.T he tridentate ligand in 4 adopts ad istorted-pyramidal geometry with the long average C À Nbond lengths [1.420 ,cf.…”

Squeezing Bi: PNP and P2N3 Pincer Complexes of Bismuth(III

“…These phase-dependent structural outcomes point to facile interconversion between the two geometries, such that solvent and lattice effects can easily favour one or the other outcome, which is in line with the reportedly small inversion barriers at hypervalent bismuth centres. 56,57 Notably, the P1-Bi bond length in 2b within the sum of the van der Waals radii (3.59 Å) but significantly longer than the sum of the covalent radii for the two elements (2.14 Å), suggesting at least partial ionic character. Indeed, the crystallographically determined structural features of 2b are well-reproduced (Table 1) by DFT calculations performed on the hypothetical triflate-free dication [PNP-Bi] 2+ .…”

Formation of a Sterically Crowded 1,6,6αλ4-Triselenapentalene and 4H-Selenopyran-4-selones Fused with Two Bornane Skeletons Through the Reaction of d-Camphor p-Toluenesulfonylhydrazone With a Base and Elemental Selenium

“…It was assumed that the unusual selenium-oxygen replacement of 1,6,6aλ 4 -triselenapentalene ring forming 1,2-diselenole ring and a carbonyl group would proceed through oxidation of an electron-rich selenium atom, Se (1) or Se(3) of 6, via the plausible bond-switching tautomerization between 6′ and 6″. [38][39][40][41][42][43][44][45][46][47][48][49][50] In addition, the structure of 11, bearing an isolated carbonyl group, strongly suggested that the formation of 1,6,6αλ 4 oxadiselenapentalene ring would be unfavorable due to the weak attractive interaction between the selenium atoms of the 1,2-diselenole ring and the oxygen atom of the neighboring carbonyl group.…”

“…1,6,6αλ 4 -Triselenapentalenes D and their oxygen or nitrogen analogs are classified to be bicyclic 10-S-3 type sulfuranes having three sulfur atoms with a central hypervalent sulfur atom in the heteroaromatic ring system, and their structures, chemical reactivity, and their synthetic methods have been extensively investigated during these decades. [38][39][40][41][42][43][44][45][46][47][48][49][50] However, in contrast to 1,6,6αλ 4 -trithiapentalenes D, only a few synthetic studies on their selenium analogs, such as 1,6,6αλ 4 triselenapentalenes E, [51][52][53][54][55] 1,6,6αλ 4 -thiadiselenapentalenes, and 1,6,6αλ 4 -dithiaselenapentalenes F, [56][57][58] have been carried out to date may be due to the difficulty in the preparation of suitable 1,3,5-triselenoxo intermediates. The general structures of compounds D-F are shown in Figure 1.…”

“…1,3,5-Trithiones are generally recognized as the synthetic precursors of 1,6,6aλ 4 -trithiapentalenes. [38][39][40][41][42][43][44][45][46][47][48][49][50] Therefore, it was assumed that the precursor of 1,6,6aλ 4 -triselenapentalene 6 should be 1,3,5-triselone or its alkeneselenolate-type intermediates J formed through homologation of borneneselenolate ion B at the C-3 position. Actually, treatment of compound 1 with t-BuOK and elemental selenium in HMPA afforded only 2, 3, and 5, and neither 6, 7, nor 8 were found at all in the crude products as shown in Table 1.…”