Ab initio studies on isomers of macropolyhedral borane ions [B₂₀H₁₈]ⁿ (n = 0, –2, –4)

Abstract

Various isomers of macropolyhedral borane ions [B20H18]n (n = 0, -2, -4) are investigated by using the density functional theory methods at RB3LYP/6-31+G* and RB3LYP/6-31G* levels to obtain the optimized geometries, harmonic vibrational frequencies, electron structures, and the stability order. The calculated results show that optimized bond lengths are consistent with the available experimental values and the natural populations, taking [a2 -B20H18]4- (4) as an example, are also in agreement with NMR spectra. The calculated vibrational frequencies are all real, so all of these isomers could be stable, among which [a2 -B20H18]2- (3) and [a2 -B20H18]0 (7) are considered for the first time in this paper. On the basis of the contour maps of molecular orbitals, the delocalized characteristic of molecular orbitals and the possible redox mechanism of these ions are also discussed. Moreover, the analysis on counting of skeletal bonding electrons shows that the isomers (1)-(6) obey the electronic requirement predicted by the mno rule, whereas the newly predicted isomer (7) does not match the mno rule.

Solid‐State Reactions of Eicosaborate [B20H18]2− Salts and Complexes

“…Silver(I) atoms in 1c-1 e, 2c,2dand 2f are tetracoordinated and realize tetrahedral geometry.I n1d, neither of the two symmetrically independents ilver atoms is connected with the anion; Ag1 is connected with four PPh 3 ligands and Ag2 with three PPh 3 ligands and aw ater molecule instead. [45] It is interesting that coordination of silver atoms in 1e is realized throught he same B5-B8 edges of the dimeric [trans-B 20 H 18 ] 2À as was found in the complex {1-2,5-8-[Ag 2 (Ph 3 P) 4 [B 10 H 10 ]]}; prepared in the presence of CF 3 COOH. In the case of 1c and 2c each silver atom is connected with three PPh 3 ligands, thus, it is connected with am acropolyhedral anion through av ertex (coordination polyhedron is AgHP 3 ).…”

“…It is worth mentioning, that in {5-8,5'-8'-1e}asilver atom is connected with an edge containing equatorial boron atomso nly,w hich is av ery rare case for coinage metal complexes with decahydro-closo-decaboron cages,b ecause apical atoms are more negatively charged. [45] It is interesting that coordination of silver atoms in 1e is realized throught he same B5-B8 edges of the dimeric [trans-B 20 H 18 ] 2À as was found in the complex {1-2,5-8-[Ag 2 (Ph 3 P) 4 [B 10 H 10 ]]}; prepared in the presence of CF 3 COOH. [33] It seemst hat trifluoroacetic acid affects the location of metal atom for both the [B 10 H 10 ] 2À and[ trans-B 20 H 18 ] 2À boron cluster anions.…”

“…Indeed, here the AgH 2 P 2 coordination polyhedron was found and {5–8,5′–8′‐ 1 e } and {7–10,7′–10′‐ 2 d } coordination isomers were obtained. It is worth mentioning, that in {5–8,5′–8′‐ 1 e } a silver atom is connected with an edge containing equatorial boron atoms only, which is a very rare case for coinage metal complexes with decahydro‐ closo ‐decaboron cages, because apical atoms are more negatively charged . It is interesting that coordination of silver atoms in 1 e is realized through the same B5–B8 edges of the dimeric [ trans ‐B 20 H 18 ] 2− as was found in the complex {1‐2,5‐8‐[Ag 2 (Ph 3 P) 4 [B 10 H 10 ]]}; prepared in the presence of CF 3 COOH .…”

Reversible single-crystal-to-single-crystal photoisomerization of a silver(i) macropolyhedral borane

“…The hydrogen atom is in the apical vertex of the macropolyhedral borane that has the most negative charge, as shown by DFT calculations. 12 As a result, the linkage type of the complex can be termed as [10,10′-1].…”

Photochromic System among Boron Hydrides: The Hawthorne Rearrangement

“…Access to innovative and/or more efficient technological devices is directly linked to the development of usable functionalized materials such as responsive molecular switches. , Therefore, the growing needs of industry demand a systematic exploration of molecules displaying attractive photophysical and photochemical properties, requiring the fine understanding at a fundamental level of the molecular mechanisms that govern the photoprocesses coming into play. In this framework, boron hydrides − represent a family of compounds whose rich structural variety offers a diverse set of tunable optical properties with potential applications such as blue lasing, , strongly phosphorescent luminophores, singlet oxygen production, and energy-transfer composite materials . Other borane-based large systems have recently emerged as appealing materials for medicinal applications, whereas the functionalization of icosahedral boranes, carboranes, and metallacarboranes has a growing interest as alternatives to the traditional organic and organometallic material building blocks .…”