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    A Zwitterionic Tetrastanna(II) Cyclic Crown
    (John Wiley and Sons Inc, 2023) Sahoo, Padmini; Chibde, Purva; Das, Satyabrata; Banerjee, Subhrashis; Vanka, Kumar; Gonnade, Rajesh G.; Yıldız, Cem. B.; Majumdar, Moumita
    A 12-membered zwitterionic tetrastanna(II) cycle 1 having a crown ether-like topology has been isolated from the deprotonation of 1,1?-methylenediimidazole (B) with two equivalents of Sn[N(SiMe3)2]2 (A). The solid-state structure and NMR analysis confirms the tetrastanna(II) cycle 1 to be comprised of two stannate(II) and two stannyliumylidene ion pairs in alternating positions of the heterocycle. Computational analysis shows greater nucleophilicity at the proximally located stannate(II) centers. Nonetheless, the tetrastanna(II) cycle 1 remains poorly reactive due to engagement of SnII lone pair electrons in intramolecular donor-acceptor interactions. Simple deprotonation reaction between Sn[N(SiMe3)2]2 (A) and N-(diisopropylphenyl)imidazole (C) in equimolar ratio has led to a stannylene 2, involving the formation of a Sn?C covalent bond with the anionic imidazol-2-yl carbon center along with the release of NH(SiMe3)2. Compound 2 exists as a dimer, where the unsubstituted ring nitrogen atom coordinated intermolecularly to the other stannylene center.
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    Coordination Chemistry of the Antimony(III) and Bismuth(III) Cations using Bis(?-iminopyridine) as Ligand
    (John Wiley and Sons Inc, 2023) Haldar, Hritwik; Yıldız, Cem Burak; Majumdar, Moumita
    Bis(alpha-iminopyridine) L has been employed as the redox non-innocent Schiff-base ligand to coordinate with cationic antimony(III) and bismuth(III) centers. Mono- and di- cationic compounds: [LSbCl2][CF3SO3] 1, [LBiCl2][CF3SO3] 2, [LSbCl2]2[Sb2Cl8] 3, [LBiCl2]2[Bi2Cl8] 4, [LSbCl][CF3SO3]2 5, [LBiCl][CF3SO3]2 6 have been isolated and characterized using single crystal X-ray crystallography in the solid-state and solution-state NMR studies. These compounds have been prepared from PnCl3 (Pn=Sb, Bi) and chloride abstracting agent such as Me3SiCF3SO3 or AgCF3SO3 in the presence of L. The Bi tri-cationic species forms heteroleptic compound 7, being coordinated by two types of Schiff-base donors L and L?. The latter has been in situ generated by the cleavage of one of the two imines present in L.
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    Intramolecular donor-stabilized tetra-coordinated germanium(iv) di-cations and their Lewis acidic properties
    (Royal Society of Chemistry, 2023) Yıldız, Cem Burak; Khan, Souvik; Gonnade, Rajesh G.; Majumdar, Moumita
    We report the first examples of intramolecular phosphine-stabilized tetra-coordinated germanium(iv) di-cationic compounds: [LiPr2Ge][CF3SO3]23iPr and [LPh2Ge][CF3SO3]23Ph (LiPr = 6-(diisopropylphosphanyl)-1,2-dihydroacenaphthylene-5-ide; LPh = 6-(diphenylphosphanyl)-1,2-dihydroacenaphthylene-5-ide). The step wise synthetic strategy involves the isolation of neutral and mono-cationic Ge(iv) precursors: [LiPr2GeCl][X] (X = GeCl31iPr, OTf 2iPr), [LPh2GeCl2] 1Ph and [LPh2GeCl][OTf] 2Ph. Both 3iPr and 3Ph exhibit constrained spiro-geometry. DFT studies reveal the dispersion of di-cationic charges over P-Ge-P sites. Anion or Lewis base binding occurs at the Ge site resulting in relaxed distorted trigonal bipyramidal/tetrahedral geometry. 3iPr and 3Ph activate the Si-H bond initially at the P-site. The hydride ultimately migrates to the Ge-site rapidly giving [LPh2GeH][CF3SO3] 3PhH, while sluggishly forming [LiPr2GeH][CF3SO3] 3iPrH. Compounds 3iPr and 3Ph were tested as catalysts for the hydrosilylation of aromatic aldehydes. While catalytic hydrosilylation proceeded via the initial Et3Si-H bond activation in the case of 3iPr, compound 3Ph as a catalyst showed a masked Frustrated Lewis Pair (FLP) type reactivity in the catalytic cycle.