• Prasenjit Das

      Articles written in Journal of Chemical Sciences

    • Crystal structure and solid-state properties of discrete hexa cationic trinuclear zinc triazole cluster

      Chatla Naga Babu Paladugu Suresh Arruri Sathyanarayana Prasenjit Das Ganesan Prabusankar

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      A linear trinuclear cluster of the type [{Zn3 (HTrz)6 (H2O)6}6+ (NO$_{3}^{−}$)6 (H2O)] (ZnT) has been synthesized by one-pot reaction between 1,2,4-triazole and Zn(NO3).6H2O. Molecule consists of three Zn2+ ions linearly connected by 1,2,4-triazole with tri-fold symmetry. The coordination geometry around the zinc centre is octahedral with zinc-zinc separation of 3.810 Å. The coordination environment of central Zn2+ ion is satisfied by nitrogen atoms of six 1,2,4-triazoles, while the geometry of terminal Zn2+ ions is fulfilled by nitrogen atoms of three 1,2,4-triazoles and three water molecules. The thermal and absorption properties of ZnT have been reported for the first time.

    • Possible C-F bond activation by B(C6F5)3/lutidine and Al(C6F5)3/lutidine frustrated Lewis pair: an in silico study


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      The activation of the C-F bond in 1-fluorobutane, 1, 1-difluorobutane and 1, 1, 1-trifluorobutaneby some frustrated Lewis pair (FLP) has been assessed by DFT based computational study. The FLPs areconstructed from lutidine Lewis base in association with either B(C6F5)3 or Al(C6F5)3. Thermodynamics andkinetics of the reactions are studied, which reveals the concerning bond activation mediated by the Al(C6-F5)3/lutidine FLP is more favourable than the analogous reactions mediated by the B(C6F5)3/lutidine pair.Therefore, the Al(C6F5)3 acid is superior to the B(C6F5)3 acid to construct an effective FLP for some unusualbond activation. The EDA-NOCV study together with the WBI calculation reveals the C-F bond activation inthe studied systems takes place by the cooperative action of the FLP partners. The activation strain modelreveals the strain energy of the reactants to reach the transition state (TS) rather than the interaction energy atthe TS is the decisive factor to the TS barrier height of the concerned reactions.

      The activation of C-F bond in 1-fluorobutane, 1, 1-difluorobutane and 1, 1, 1-trifluorobutane by B(C6F5)3/lutidine and Al(C6F5)3/lutidine pairs has been assessed computationally. The Al(C6F5)3/lutidine pair is superior to the B(C6F5)3/lutidine pairs for such unusual bond activation as revealed by this study.

    • BSinGe4-n + (n =0-2): prospective systems containing planar tetracoordinate boron (ptB)


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      The potential energy surface (PES) has been explored for BSinGe4−n+ (n = 0-2) systems using density functional theory (DFT). The global minima (1a, 1b, and 1c) of the considered systems contain a planar tetracoordinate boron (ptB) center. The neutral states of the systems do not have a ptB in the global minimum structures. The designed BGe4+, BSiGe3+, and BSi2Ge2+ systems have 18 valence electrons. TheCCSD(T)/aug-cc-pVTZ level of theory has been applied to compute the relative energies of the low-lying isomers with respect to the global minima. The dynamical stability of BSinGe4−n+ (n = 0-2) systems is confirmed from the atom-centered density matrix propagation (ADMP) simulation over 20 ps of time at temperatures of 300 K and 500 K. The natural charge computations show that the charges on the ptB are highly negative, indicating strong r-acceptance from the peripheral atoms. The 1a, 1b, and 1c structures of BGe4+, BSiGe3+, and BSi2Ge2+ systems, respectively, have r/p-dual aromaticity as predicted from the nucleus-independent chemical shift (NICS) values.

      Density functional theory (DFT) based computation predicts the presence of a planar tetracoordinate boron (ptB) in the global minimum energy structures of BSinGe4−n+ (n = 0−2) systems. The systems are kinetically stable and show σ- and π- electronic delocalization.

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