Behavior of the Local Reactivity Descriptors during Complexation:  A Case Study of BXX‘X‘ ‘NH₃(X, X‘, X‘‘= H, F)

Abstract

The behavior of local reactivity descriptors such as condensed fukui functions, “relative electrophilicity”, and “relative nucleophilicity” was studied as the complexation reaction of BH3 or fluoroboranes and NH3 proceeds. This study reveals the change of these descriptors of different atoms during the reaction. The case study indicates the general properties of descriptors in a reactive surface.

Electrophilicity Index

“…Relative electrophilicity and relative nucleophilicity are defined as s k + / s k - and s k - / s k + , respectively . Although they perform better ,,− than the Fukui function or local softness on certain occasions, they suffer from various drawbacks. ,,,, In light of the local HSAB principle, , a softness matching index has been defined − for analyzing the regioselectivity as when atoms i and j of a nucleophile form a cycloadduct through the atoms k and l of an electrophile. The corresponding philicity 93 related quantity was also reported recently …”

Conformational Preference in Heteroatomic Analogues of Ethane, H3X−YH3 (X = B, Al; Y = N, P): Implications of Charge Transfer

“…Conformational preferences arise due to special stabilities at certain angular orientations compared to other angles. Steric repulsions between the neighboring atoms in the eclipsed conformer that are relieved in the staggered conformer have been generally understood to be the origin of such staggered preference. , However, recently, there has been a renewed interest in the search for the origin of such conformational preference in organic homo-binuclear molecular systems − as conformational flexibility amounts to one of the basic processes in structural chemistry.…”

Separability of local reactivity descriptors

“…Recently, we discussed the behaviour of reactivity descriptors during complexation of BH 3 and NH 3 using ab-initio calculation. 24 We have seen that the non-interacting values of f + or fare approached only by atoms of fragmented species for complex anion or cation respectively. Our discussion in §3 for complex AB analytically justifies the results obtained earlier.…”

“…However, the sum of the condensed RE and RN of all atoms in a system is not a fixed quantity. Equation (24) implies that the sum of RE or RN for a non-interacting dimer is twice that of the sum for all atoms of the monomer. On similar lines, results can be generalized for non interacting A n .…”

“…Recently, we have discussed the behavior of the reactivity descriptors during complexation of BH 3 and NH 3 using ab-initio calculation. 24 The paper has been organized as follows. In §2 we present a brief theoretical background defining the local descriptors and how these have been used in the study of reactivity and selectivity.…”