Maximal occupation by bases of π‐hole bands surrounding linear molecules

Abstract

Linear molecules such as CO2 contain a positive π‐hole ring that surrounds C on the molecule's equator. Quantum calculations examine the question as to how many bases can simultaneously bind to this ring. Linear molecules examined are TO2, where T = C, Si, Ge, Sn; bases are NCH and NH3. CO2 engages in the weakest of the tetrel bonds, and can bind up to three NCH and two NH3. Unlike σ‐hole tetrel bonds, Si forms the strongest tetrel bonds, with interaction energies as high as 43 kcal/mol with NH3. But like GeO2, SiO2 can sustain only two bases in its equatorial ring. The π‐hole ring of SnO2 can engage in up to four tetrel bonds with either NCH or NH3, even though these bonds are weaker than those with GeO2 or SiO2. As all of these complexes cast TO2 in the role of multiple electron acceptor, the resulting negative cooperativity makes each successive bond weaker than its predecessor as bases are added, as well as reducing the magnitude of the central molecule's π‐hole.

Conformation-Associated C···dz2-PtII Tetrel Bonding: The Case of Cyclometallated Platinum(II) Complex with 4-Cyanopyridyl Urea Ligand

“…For both conformers, two positive regions were revealed: first, on the center of the pyridine ring on both sides of the cycle (Vs,max = 16-20 kcal/mol (3A) and 11-17 kcal/mol (3B)) and second, a belt between the C and N atoms of the cyano group ring (Vs,max = 14 for 3A and 12 kcal/mol for 3B). Such belt is typical for cyano groups [72].…”

“…For both conformers, two positive reg were revealed: first, on the center of the pyridine ring on both sides of the cycle (Vs,m 16-20 kcal/mol (3A) and 11-17 kcal/mol (3B)) and second, a belt between the C an atoms of the cyano group ring (Vs,max = 14 for 3A and 12 kcal/mol for 3B). Such b typical for cyano groups [72]. For a more precise analysis of the presence of π-holes on carbon atoms, we structed the dependence of the MEP (0.001) value on the angle in the plane pas through the CN group and the pyridine ring [73].…”

Noncovalent chalcogen and tetrel bonding interactions: Spectroscopic study of halide–carbonyl sulfide complexes

“…22 Noncovalent chalcogen and tetrel bonding interactions have been studied theoretically at multiple levels of theory in order to ascertain the strength of binding, as well as binding motifs. [23][24][25][26] In addition, computational studies have also focussed on the relation of noncovalent bond formation with spectroscopic shifts. [27][28][29][30][31] Chalcogen and tetrel bonding interactions have also been studied experimentally, 32 utilizing various techniques in order to capture key structural and energetic effects.…”

“…Noncovalent chalcogen and tetrel bonding interactions have been studied theoretically at multiple levels of theory in order to ascertain the strength of binding, as well as binding motifs 23–26 . In addition, computational studies have also focussed on the relation of noncovalent bond formation with spectroscopic shifts 27–31 .…”