Overlap control and stability of polyhedral molecules. closo-Carboranes

Jemmis, Eluvathingal D.

doi:10.1021/ja00389a021

Cited by 157 publications

(103 citation statements)

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“…[37] The energies of the six optimised isomers 13 a-e, which involve BH, CH or P fragments in the capping position, reveal that BH is preferred over both P and CH, at both B3LYP and G3B3 levels ( Table 2 and Figure S2 in the Supporting Information). [44] The stability of 13 a over 13 c could be due to the greater C À C bond strength as compared to C À P ( Table S4 in the Supporting Information). The adjacent carbon basal ring (13 a) again would be the thermodynamic product as in EH 2 C 2 P 3 + (E = P, As, Sb), [22] but conversion to 13 b via a 13 e intermediate could also be feasible due to its relatively low energy (34.1 kcal mol À1 ).…”

Section: Wwwchemeurjorgmentioning

confidence: 99%

Electronic Structure and Bonding in Neutral and Dianionic Boradiphospholes: R′BC₂P₂R₂ (R=H, tBu, R′=H, Ph)

Usharani

Poduska

Nixon

et al. 2009

Chemistry A European J

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Classical and non-classical isomers of both neutral and dianionic BC(2)P(2)H(3) species, which are isolobal to Cp(+) and Cp(-), are studied at both B3LYP/6-311++G(d,p) and G3B3 levels of theory. The global minimum structure given by B3LYP/6-311++G(d,p) for BC(2)P(2)H(3) is based on a vinylcyclopropenyl-type structure, whereas BC(2)P(2)H(3)(2-) has a planar aromatic cyclopentadienyl-ion-like structure. However, at the G3B3 level, there are three low-energy isomers for BC(2)P(2)H(3): 1) tricyclopentane, 2) nido and 3) vinylcyclopropenyl-type structures, all within 1.7 kcal mol(-1) of each other. On the contrary, for the dianionic species the cyclic planar structure is still the minimum. In comparison to the isolobal Cp(+) and H(n)C(n)P(5-n)(+) isomers, BC(2)P(2)H(3) shows a competition between pi-delocalised vinylcyclopropenyl- and cluster-type structures (nido and tricyclopentane). Substitution of H on C by tBu, and H on B by Ph, in BC(2)P(2)H(3) increases the energy difference between the low-lying isomers, giving the lowest energy structure as a tricyclopentane type. Similar substitution in BC(2)P(2)H(3)(2-) merely favours different positional isomers of the cyclic planar geometry, as observed in 1) isoelectronic neutral heterodiphospholes EtBu(2)C(2)P(2) (E = S, Se, Te), 2) monoanionic heterophospholyl rings EtBu(2)C(2)P(2) (E = P(-), As(-), Sb(-)) and 3) polyphospholyl rings anions tBu(5-n)C(n)P(5-n) (n = 0-5). The principal factors that affect the stability of three-, four-, and five-membered ring and acyclic geometrical and positional isomers of neutral and dianionic BC(2)P(2)H(3) isomers appear to be: 1) relative bond strengths, 2) availability of electrons for the empty 2p boron orbital and 3) steric effects of the tBu groups in the HBC(2)P(2)tBu(2) systems.

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Section: Wwwchemeurjorgmentioning

confidence: 99%

Electronic Structure and Bonding in Neutral and Dianionic Boradiphospholes: R′BC₂P₂R₂ (R=H, tBu, R′=H, Ph)

Usharani

Poduska

Nixon

et al. 2009

Chemistry A European J

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“…By the way, Jemmis had ever explained the stability difference of

{normalB}_{n} {normalH}_{n}^{2 -}

(5 ≤ n ≤ 7) series by the matching of the cap orbital and ring orbital, and obtained that the BH prefer to be the cap of five‐membered ring rather than three‐ and four‐membered ring. In addition, for

{normalB}_{n} {normalH}_{n}^{2 -}

(5 ≤ n ≤ 7) series, the calculated formation energy indicates that the

{normalB}_{5} {normalH}_{5}^{2 -}_{}

is less stable than

{normalB}_{6} {normalH}_{6}^{2 -}_{}

and

{normalB}_{7} {normalH}_{7}^{2 -}_{}

.…”

Section: The Qualitative Analysis Of the Normalbnnormalhn2− And C2bnmentioning

confidence: 99%

“…According to cap-ring model, [89,90] the stability of position isomers of C 2 B n22 H n (5 n 7) is related to the matching of the cap and ring fragments, while the CH group prefers to be the cap of three-and four-membered ring rather than five-membered ring. [90] In addition, for C 2 B n22 H n (5 n 7) series, the quantitative computational results indicate that the two carbon atoms prone to occupy the lowcoordinate and nonadjacent sites. [64,66,92] Therefore, in C 2 B 3 H 5 and C 2 B 4 H 6 , the two C atoms prefer to occupy the cap sites as illustrated in Figure 1.…”

Section: Full Papermentioning

confidence: 99%

“…To interpret the stability difference of B n H 22 n and C 2 B n22 H n (5 n 7) by qualitative point group method, only the conformations with D nh symmetry will be investigated in this article, as illustrated in Figure 1. By the way, it should be mentioned that the relative stability of various isomers of carborane C 2 B n22 H n (5 n 7) had ever been studied by Williams, [64] Jemmis, [65,66] Gimarc, [54,67] and McKee. [68] The geometries of B n H 22 n (5 n 7), 1,5-C 2 B 3 H 5 , 1,6-C 2 B 4 H 6 , and 1,7-C 2 B 5 H 7 displayed in Figure 1 are optimized and confirmed by vibration frequency analysis at B3LYP/def2-TZVPP level [69] with Gaussian 09 package, [70] where the B3LYP/def2-TZVPP method is always used as structure optimization method for boranes and borane analogs.…”

Section: Introductionmentioning

confidence: 99%

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A theoretical study on the stability difference of the borane BnHn2− and carborane C₂B_n₋₂H_n(5 ≤ n ≤ 7) clusters

Liao

Chai

Zhu

2014

Int. J. Quantum Chem.

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In order to study the electronic structure and structural stability of borane B n H 22 n and carborane C 2 B n22 H n (5 n 7) clusters, especially the stability difference between the borane B 5 H 22 5 and carborane C 2 B 3 H 5 . The frontier orbital energy levels of the borane B n H 22 n and carborane C 2 B n22 H n (5 n 7) clusters are calculated at CCSD(T)/aug-cc-pVXZ//B3LYP/def2-TZVPP level. The results are further analyzed by qualitative frontier orbital method based on the cap-ring interaction. The results reveal that: (1) the larger E gap (HOMO-LUMO energy gap) of carborane C 2 B n22 H n (5 n 7) clusters than borane B n H 22 n (5 n 7) clusters originates from the more effective cap-ring orbital overlap of carborane C 2 B n22 H n (5 n 7) clusters than that of borane B n H 22 n (5 n 7) clusters; (2) the smallest E gap of the borane B 5 H 22 5 results from the highest energy level of the ring symmetry-adapted linear combination orbital of B 5 H 22 5 cluster; and (3) the largest E gap of the carborane C 2 B 3 H 5 is induced by the most effective cap-ring orbital interaction of C 2 B 3 H 5 cluster.

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“…The high reactivity of B 7 H À2 7 (D 5h ) is attributed to the poor interaction between B 5 H 5 ring and the BH fragments [51,52]. Size of B 5 H 5 ring is large enough to have optimum overlap between p-MOs of the ring and MOs of the two BH fragments.…”

Section: Relative Stability and Bonding In The Pentagonal Bipyramidalmentioning

confidence: 99%

Structure and bonding of MCB5H7 and its sandwiched dimer CB5H6M–MCB5H6 (M=Si, Ge, Sn): Isomer stability and preference for slip distorted structure

Satpati¹

2008

Journal of Organometallic Chemistry

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Overlap control and stability of polyhedral molecules. closo-Carboranes

Cited by 157 publications

References 4 publications

Electronic Structure and Bonding in Neutral and Dianionic Boradiphospholes: R′BC₂P₂R₂ (R=H, tBu, R′=H, Ph)

Electronic Structure and Bonding in Neutral and Dianionic Boradiphospholes: R′BC₂P₂R₂ (R=H, tBu, R′=H, Ph)

A theoretical study on the stability difference of the borane BnHn2− and carborane C₂B_n₋₂H_n(5 ≤ n ≤ 7) clusters

Structure and bonding of MCB5H7 and its sandwiched dimer CB5H6M–MCB5H6 (M=Si, Ge, Sn): Isomer stability and preference for slip distorted structure

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Overlap control and stability of polyhedral molecules. closo-Carboranes

Cited by 157 publications

References 4 publications

Electronic Structure and Bonding in Neutral and Dianionic Boradiphospholes: R′BC2P2R2 (R=H, tBu, R′=H, Ph)

Electronic Structure and Bonding in Neutral and Dianionic Boradiphospholes: R′BC2P2R2 (R=H, tBu, R′=H, Ph)

A theoretical study on the stability difference of the borane BnHn2− and carborane C2Bn−2Hn(5 ≤ n ≤ 7) clusters

Structure and bonding of MCB5H7 and its sandwiched dimer CB5H6M–MCB5H6 (M=Si, Ge, Sn): Isomer stability and preference for slip distorted structure

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Electronic Structure and Bonding in Neutral and Dianionic Boradiphospholes: R′BC₂P₂R₂ (R=H, tBu, R′=H, Ph)

Electronic Structure and Bonding in Neutral and Dianionic Boradiphospholes: R′BC₂P₂R₂ (R=H, tBu, R′=H, Ph)

A theoretical study on the stability difference of the borane BnHn2− and carborane C₂B_n₋₂H_n(5 ≤ n ≤ 7) clusters