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      https://www.ias.ac.in/article/fulltext/jcsc/128/10/1663-1669

    • Keywords

       

      Sulfuranes; isolobal analogy; oligo-sulfuranes; electronegativity perturbation.

    • Abstract

       

      We studied the effect of electronegativity perturbation on the isolobal behavior of tetra-coordinate hypervalent compounds of S (sulfuranes, SL₄, L is any atom or group which can provide one electron for S-L bonding). Though formally the fragment SL₄ obtained from SL6 is an isolobal equivalent of CH₂, a qualitative molecular orbital study shows that only SF₂H₂ with equatorial F atoms is a practical isolobal substitute for CH₂ and can form oligomers, (SF₂H₂)₂, (14), (SF₂H₂)₃, (15) and (SF₂H₂)₄, (16) analogous to ethylene, cyclopropane and cyclobutane, respectively. DFT computations at the B2PLYP/6-311++g(d,p), MP2/ aug-ccpVTZ and B3LYP/6-311++g(d,p) levels confirm these structures to be minima on the PES. The skeletal S-S bonds in these structures are formed solely by the bonding combination of anti-bonding fragment orbitals of SF₂H₂. In contrast, per-fluorination, the usual way to stabilize hypervalent structures, is found to have an opposite effect here. Calculations at the same levels show (SF₄)₂, (SF₄)₃, and (SF₄)₄ not to be minima. The highly stable HOMO of SF₄ fragment and large HOMO-LUMO gap makes SF₄ a stable entity, preventing it from oligomerization. Out of the various isomers of SFnH₄−n, n = 0-4, only SF₂H₂ with equatorial F atoms can form oligomeric sulfuranes. Substitution of F by heavier analogs of the group did not lead to any stable oligomers.

    • Author Affiliations

       

      CHAKKINGAL P PRIYAKUMARI1 ELUVATHINGAL D JEMMIS2

      1. School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram, CET Campus, Thiruvananthapuram, Kerala 695 016, India
      2. Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, Karnataka 560 012, India
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