TY - JOUR

T1 - Mechanism of generation of Closo -decaborato amidrazones.

T2 - Intramolecular non-covalent B-H⋯π(Ph) interaction determines stabilization of the configuration around the amidrazone CN bond

AU - Burianova, Valeria K.

AU - Bolotin, Dmitrii S.

AU - Mikherdov, Alexander S.

AU - Novikov, Alexander S.

AU - Mokolokolo, Pennie Petrus

AU - Roodt, Andreas

AU - Boyarskiy, Vadim P.

AU - Dar'In, Dmitry

AU - Krasavin, Mikhail

AU - Suslonov, Vitalii V.

AU - Zhdanov, Andrey P.

AU - Zhizhin, Konstantin Yu

AU - Kuznetsov, Nikolay T.

PY - 2018/6/7

Y1 - 2018/6/7

N2 - Three types of N(H)-nucleophiles, viz. hydrazine, acetyl hydrazide, and a set of hydrazones, were used to study the nucleophilic addition to the CN group of the 2-propanenitrilium closo-decaborate cluster (Ph3PCH2Ph)[B10H9NCEt], giving N-closo-decaborato amidrazones. A systematic mechanistic study of the nucleophilic addition is provided and included detailed synthetic, crystallographic, computational and kinetic work. As a result, two possible mechanisms have been proposed, which consist of firstly a consecutive incorporation of two Nu(H) nucleophiles, with the second responsible for a subsequent rapid proton exchange. The second possible mechanism assumes a pre-formation of a dinuclear [Nu(H)]2 species which subsequently proceeds with the nucleophilic attack on the boron cluster. The activation parameters for hydrazones indicate a small dependence on bond formation [ΔH‡ = 6.8-15 kJ mol-1], but significantly negative entropies of activation [ΔS‡ ranges from -139 to -164 J K-1 mol-1] with the latter contributing some 70-80% of the total Gibbs free energy of activation, ΔG‡. In the X-ray structure of (Z)-(Ph3PCH2Ph)[B10H9N(H)C(Et)NHNCPh2], very rare intramolecular non-covalent B-H⋯π(Ph) interactions were detected and studied by DFT calculations (M06-2x/6-311++G∗∗ level of theory) and topological analysis of the electron density distribution within the framework of Bader's theory (QTAIM method). The estimated strength of these non-covalent interactions is 0.8-1.4 kcal mol-1.

AB - Three types of N(H)-nucleophiles, viz. hydrazine, acetyl hydrazide, and a set of hydrazones, were used to study the nucleophilic addition to the CN group of the 2-propanenitrilium closo-decaborate cluster (Ph3PCH2Ph)[B10H9NCEt], giving N-closo-decaborato amidrazones. A systematic mechanistic study of the nucleophilic addition is provided and included detailed synthetic, crystallographic, computational and kinetic work. As a result, two possible mechanisms have been proposed, which consist of firstly a consecutive incorporation of two Nu(H) nucleophiles, with the second responsible for a subsequent rapid proton exchange. The second possible mechanism assumes a pre-formation of a dinuclear [Nu(H)]2 species which subsequently proceeds with the nucleophilic attack on the boron cluster. The activation parameters for hydrazones indicate a small dependence on bond formation [ΔH‡ = 6.8-15 kJ mol-1], but significantly negative entropies of activation [ΔS‡ ranges from -139 to -164 J K-1 mol-1] with the latter contributing some 70-80% of the total Gibbs free energy of activation, ΔG‡. In the X-ray structure of (Z)-(Ph3PCH2Ph)[B10H9N(H)C(Et)NHNCPh2], very rare intramolecular non-covalent B-H⋯π(Ph) interactions were detected and studied by DFT calculations (M06-2x/6-311++G∗∗ level of theory) and topological analysis of the electron density distribution within the framework of Bader's theory (QTAIM method). The estimated strength of these non-covalent interactions is 0.8-1.4 kcal mol-1.

KW - ANION DERIVATIVES

KW - B-H ACTIVATION

KW - CENTER-DOT-PI

KW - CRYSTAL-STRUCTURES

KW - HYDROGEN-BOND

KW - NEUTRON-CAPTURE THERAPY

KW - NITRILIUM DERIVATIVES

KW - NUCLEOPHILIC-ADDITION

KW - PLATINUM(II) COMPLEXES

KW - SUBSTITUTION-REACTIONS

UR - http://www.scopus.com/inward/record.url?scp=85048006252&partnerID=8YFLogxK

UR - http://www.mendeley.com/research/mechanism-generation-closo-decaborato-amidrazones-intramolecular-noncovalent-bh%CF%80ph-interaction-deter

U2 - 10.1039/C8NJ01018H

DO - 10.1039/C8NJ01018H

M3 - Article

AN - SCOPUS:85048006252

VL - 42

SP - 8693

EP - 8703

JO - New Journal of Chemistry

JF - New Journal of Chemistry

SN - 1144-0546

IS - 11

ER -