• Sundargopal Ghosh

Articles written in Journal of Chemical Sciences

• Synthesis and reactivity of dimolybdathiaborane cluster [(CpMo)2B4SH6] (Cp = $\eta^5^-C5Me5) Chemistry and reactivity of dimolybdathiaborane, [(CpMo)2B4SH6], 1, obtained from the reaction of 2-mercaptobenzothiazole, [CpMoCl4] and [LiBH4.thf], has been explored with dinuclear metal carbonyl [Fe2(CO)9]. As a result, reaction of 1 with [Fe2(CO)9] yielded heterometallathiaborane, [(CpMo)2B4H6SFe(CO)3], 2 in good yield. Both the new compounds have been characterized in solution by 1H, 11B and 13C NMR spectroscopy and the structural types were unequivocally established by X-ray crystallographic analysis of compound 2. Cluster 2 has a bicapped octahedral geometry with the {Fe(CO)3} fragment occupying one of the high-connectivity cluster vertexes rather than a capping position. Interestingly, cluster 1 undergoes geometric changes (bicapped trigonal bipyramid → bicapped octahedron) on the addition of two-electron {Fe(CO)3} fragment to 1. • Click-generated triazole based ferrocene-carbohydrate bioconjugates: A highly selective multisignalling probe for Cu(II) ions Two Cu2+-specific colorimetric sensors, based on ferrocene-carbohydrate bioconjugates, 2, C46H56O20N6Fe and 3, C28H33O10N3Fe were designed and synthesized in good yields. Both the compounds, 2 and 3, behave as very selective and sensitive chromogenic and electrochemical chemosensor for Cu2+ ion in aqueous environment (CH3CN/H2O (2:8,$v/v$). The analytical detection limit (ADL) for receptor 2 was$7.5 \times 10^{−7}$M. The considerable changes in their absorption spectra of 2 and 3 are accompanied by the appearance of a new low energy (LE) peak at 630 nm (2:$\epsilon = 1600$M-1 cm-1 and 3: 822 M-1 cm-1). This is further accompanied by a strong colour change from yellow to dark green that allows the prospective for `naked eye’ detection of Cu2+ ion. • Dimetallaheteroborane clusters containing group 16 elements: A combined experimental and theoretical study Recently we described the synthesis and structural characterization of various dimetallaherteroborane clusters, namely nido-[(CpMo)2B4ECl$_x$H$_{6−x}\$], 1-3; (1: E = S, x = 0; 2: E = Se, x = 0; 3: E = Te, x = 1). A combined theoretical and experimental study was also performed, which demonstrated that the clusters 1-3 with their open face are excellent precursors for cluster growth reaction. In this investigation process on the reactivity of dimetallaheteroboranes with metal carbonyls, in addition to [(CpMo)2B4H6EFe(CO)3] (4: E = S, 6: E = Te) reported earlier, reaction of 2 with [Fe2(CO)9] yielded mixed-metallaselenaborane [(CpMo)2B4H6SeFe(CO)3], 5 in good yield. The quantum chemical calculation using DFT method has been carried out to probe the bonding, NMR chemical shifts and electronic properties of dimolybdaheteroborane clusters 4-6.

• Reactivity of [Cp*Mo(CO)₃Me] with chalcogenated borohydrides Li[BH₂E₃] and Li[BH₃EFc] (Cp* = (ŋ⁵-C₅Me₅); E = S, Se or Te; Fc = (C₅H₅-Fe-C₅H₄))

Reactivity of [Cp*Mo(CO)₃Me], 1 with various chalcogenide ligands such as Li[BH₂E₃] andLi[BH₃EFc]] (E = S, Se or Te; Fc = (C₅H₅-Fe-C₅H&#8324)) has been described. Room temperature reaction of 1 with Li[BH₂E₃] (E = S and Se) yielded metal chalcogenide complexes [Cp*Mo(CO)₂(ŋ2-S₂CCH3)], 2 and [Cp*Mo(CO)₂(ŋ1-SeC₂H₅)], 3. In compound 2, {Cp*Mo(CO)2} fragment adopts a four-legged piano-stool geometry with a η2-dithioacetate moiety. In contrast, treatment of 1 with Li[BH3(EFc)] (E = S, Se or Te; Fc = C₅H₅-Fe-C₅H₄) yielded borate complexes [Cp*Mo(CO)₂(μ-H)(μ-EFc)BH₂], 4-6 in moderate yields. Compounds 4-6 are too unstable and gradual conversion to [{Cp*Mo(CO)₂}₂(μ-H)(μ-EFc] (7: E = S; 8: Se) and [{Cp*Mo(CO)₂}₂(μ-TeFc)₂], 9 happened by subsequent release of BH₃. All the compounds have been characterized by mass spectrometry, IR, multinuclear NMR spectroscopy and structures were unequivocally established by crystallographic analysis for compounds 2, 3 and 7.

• Synthesis and structural characterization of a diruthenium pentalene complex, [Cp∗Ru{(Cp∗Ru)2B6H14}(Cp∗Ru)]

Treatment of nido-[1,2-(Cp*Ru)2(μ-H)2B3H7], 1 with five equivalents of Te powder led to the isolation of diruthenium pentalene analogue [(Cp*Ru){(Cp*Ru)2B6H14}(RuCp*)], 2 and a metal indenyl complex [(Cp*Ru)2B2H6C6H3 CH3], 3. The [(Cp*Ru)2B6H14] fragment in 2 may be considered as a true metal–boron analogue of η55-pentalene ligand (C8H6) and [(Cp*Ru)B2H6C6H3 CH3] fragment in 3 is an analogue of η5-indenyl ligand. The solid-state X-ray structures were unambiguously determined by crystallographic analysis of compounds 2 and 3. Further, the density functional theory (DFT) calculationswere performed to investigate the bonding and the electronic properties of 2a (Cp analogue of 2). The frontier molecular orbital analysis of both 2a and 2b (Cp analogue of [(Cp*Ru)B8H14(RuCp*)]) reveals a lower HOMO–LUMO gap indicating less thermodynamic stability

• Syntheses and structures of chalcogen-bridged binuclear group 5 and 6 metal complexes

Syntheses and structural elucidations of a series of chalcogen stabilized binuclear complexes of group 5 and 6 transition metals have been described. Room temperature reaction of [Cp*CrCl]2 (Cp* = h5- C5Me5) with Li[BH3(SePh)] afforded a Se inserted binuclear chromium complex, [(Cp*Cr)2(m-Se2SePh)2], 1.In an attempt to make the analogous complexes with heavier group 6 metals, reactions of [Cp*MCl4] (M = Mo and W) with Li[BH3(SePh)] were carried out that yielded Se inserted binuclear complexes [(Cp*M)2(m-Se)2(m-SePh)2], 2 and 3 (2: M = Mo and 3: M = W) along with known [(Cp*M)2B5H9], 4a–b (4a: M = Mo and 4b: M = W). Similarly, the reactions of [Cp*NbCl4] with Li[BH3(EPh)] (E = S or Se)followed by thermolysis led to the formation of binuclear chalcogen complexes [(Cp*Nb)2(m-E2)2], 5 and 6 (5: E = S and 6: E = Se) and known [(Cp*Nb)2(B2H6)6], 7. All these complexes have been characterized by 1H and 13C NMR spectroscopy and mass spectrometry. The structural integrity of complexes 1, 3, 5 and 6 was established by the X-ray diffraction studies. The DFT studies further exemplify the bonding interactions present in these complexes, especially the multiple bond character between the metals in 1–3.

• Correction to: Syntheses and structures of chalcogen-bridged binuclear group 5 and 6 metal complexes

• # Journal of Chemical Sciences

Volume 135, 2023
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• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019