• Meenu

      Articles written in Journal of Chemical Sciences

    • Synthesis and characterisation of some hypervalent silicon compounds

      S P Narula Ravishankar Manish Kumar Meenu

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    • Recent chemistry of hypervalent silicon(IV) compounds — Part II. Synthesis and characterisation of some new spirobicyclic five- and six-coordinated siliconate anions

      Suraj P Narula Ravi Shankar Meenu

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      Some new pentacoordinated anionic spirobicyclic silicon(IV) compounds containing the isothiocyanato group, [(C6H4O2)2SiNCS] M+; [M=K(1), Na(2), K(18-crown-6)(3), NH4(4)], have been prepared by the activation of the silicon centre of tetracoordinated silances by NCS ion. These compounds have been characterised by elemental analyses, IR, multinuclei (1H,13C and29Si) NMR and FAB mass spectroscopy. Synthesis of stable spirobicyclic hexacoordinated dianionic siliconates with six-and seven-membered oxygen-containing rings around silicon atoms, [(C7H4O3)2 Si(NCS)2]2−2B+; (B=PyH(5), 3-mepyH(6)4-mePyH(7)] and [(C8H4O4)2Si(NCS)2]2−2[3-mepyH]+(8), are also described. The complexes58 have been achieved from the reactions of appropriate cationic five-coordinate silicon (IV) intermediate with salicylic acid (57) or phthalic acid (8). The resulting compounds have been characterised by elemental analyses. IR multinuclei (1H,13C,29Si) NMR spectral data.

    • Synthesis, crystal structure determination of two-dimensional supramolecular co-ordination polymer of silver(I) with 1,2-Bis(phenylthio)ethane and its Hirshfeld surface analysis

      Rahul K Mudsainiyan Amanpreet K Jassal Meenu Arora Sukhvinder K Chawla

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      The 2-D polymeric complex (I) has the formula [Ag(phSE)(NO3)]n, which has been crystallized from methanol-acetonitrile mixture and characterized by elemental analysis and single-crystal X-ray diffraction analysis. In this polymer, each Ag(I) ion occupies distorted trigonal pyramidal geometry coordinating with two sulphur atoms from two different ligands and two oxygen atoms from two NO33 groups. Each NO3 acts as a bridging ligand coordinating through its two oxygen atoms to different Ag(I) ions. The Ag(I) ion and NO3 group are in plane with torsion angle 176.43$^{\circ}$. All the ligands adopt anti-conformation but the relative orientation of two -S-C-C-S units is perpendicular to one another such that two phenyl rings attached to the two sulphur atoms coordinating to a particular Ag ion lie on the same side. Each NO3 bridges two neighbouring Ag ions belonging to two different -S-Ag-S-C-C-S-Ag-S- tapes running along 𝑎-axis where two phenyl rings are not parallel to each other to reduce the steric hindrance and maximize packing. The adjacent chains are fused to form 2D sheet by bridging both through bidentate phSE ligand and NO3 anion stacking in 𝑎𝑏 plane. The structure consists of 4-c uninodal net where Point symbol for Ag (I) ion and net is (44.62) with sql type topology. X-ray diffraction analysis and Hirshfeld surface analysis give rise to comparable results but in Hirshfeld surface analysis, twothird times more close contacts are obtained. The fingerprint plots demonstrate that these weak non-bonding interactions are important for stabilizing the crystal packing.

    • Evaluation of micellar properties of sodium dodecylbenzene sulphonate in the presence of some salts

      ASHWANI KUMAR SOOD MEENU AGGARWAL

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      The influence of some salts (NaCl, KCl, NH4Cl and MgCl2) on the critical micelle concentration (CMC) and fraction of counterion dissociation (α) of sodium dodecylbenzene sulphonate (SDBS) have been determined by conductometric and dynamic light scattering (DLS) methods at 298.15 K. The CMC determination involves fitting of experimental conductivity-surfactant concentration data into the integral form of Boltzmanntype sigmoidal equation. The procedure provides much better results compared to the conventional and differential methods for surfactant such as SDBS that exhibits a gradual transition from pre-micellar to thepost-micellar region. The decrease in CMC of SDBS was found to be the highest in the presence of MgCl2 and least in the case of NaCl among the studied salts. The fraction of counter ion dissociation decreases sharply at lower concentrations of the salts (except NaCl) which have been discussed in terms of effective ionic charge on the micelles. Using CMC and α value, the aggregation number of the micelle, micellar surface area and packing parameter has been calculated and were seen to agree well with the corresponding literature values obtained by using fluorescence and surface tension measurements. The effect of salts on the change in micellar size and the surface charge has also been evaluated with the help of DLS experiments and transmission electron microscopy (TEM) images

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