Synthesis and Structural Characterization of a Stable Dimeric Boron(II) Dication

Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.
Angewandte Chemie International Edition (Impact Factor: 11.34). 12/2007; 46(47):9110-3. DOI: 10.1002/anie.200703616
Source: PubMed
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    ABSTRACT: Low-temperature catalytic dehydrogenation of H3Ga·NMe3 and a bicyclic guanidine [1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (hppH) or 1,5,7-triazabicyclo[4.3.0]non-6-ene (Htbn)] led to temperature-sensitive gallium hydrides H3Ga(tbn)·Htbn and [H2Ga(μ-hpp)]2. Both hydrides, which are stable only at low temperatures, were structurally characterized. A possible pathway and the role of the catalyst are discussed on the basis of NMR spectroscopic experiments and quantum chemical calculations.
    Berichte der deutschen chemischen Gesellschaft 05/2012; 2012(14). DOI:10.1002/ejic.201200102
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    ABSTRACT: Bicyclic guanidine 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (hppH) was investigated as a source of anionic or neutral ligand at antimony. Reaction of the in situ generated lithium guanidinate with SbCl3 in a 1:1 or 2:1 ratio forms the expected metathesis products Sb(hpp)nCl3–n (1, n = 1; 2, n = 2). The molecular structures of 1 and 2 were determined by X-ray diffraction, which shows chelating guanidinates and suggests the presence of a stereochemically active lone pair of electrons. The reaction of two equivalents of the neutral guanidine hppH with SbCl3 proceeds via proton transfer between the hpp fragments, affording the ion pair [hppH2][Sb(hpp)Cl3] (3), where [Sb(hpp)Cl3]– is an unusual example of a monometallic antimonate(III) anion. The molecular structure of 3 shows hydrogen bonding between two of the chlorides and the NH functionalities of the guanidinium cation.
    Berichte der deutschen chemischen Gesellschaft 02/2012; 2012(5). DOI:10.1002/ejic.201101189
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    ABSTRACT: Zinc dichloride and dimethylzinc were treated with several acyclic and bicyclic guanidines. Three different bicyclic guanidines and their potassium guanidinate salts were treated with ZnCl2. The reaction with the neutral guanidines afforded mononuclear complexes, stabilized by intramolecular hydrogen bonding. The reaction with the potassium guanidinate salts led to trinuclear complexes, which were extremely water sensitive. The reaction in the presence of added water furnished a tetranuclear complex with a central OZn4 unit in good yield, to which six guanidinate ligands were bound. The reaction of dimethylzinc with 2-[N,N′-diisopropylguanidino]pyridine and 2-[N,N′-diisopropylguanidino]quinoline afforded di- and tetranuclear Zn methyl complexes with mono- and dianionic guanidinate ligands. Dinuclear complexes of the monoanionic guanidinate ligands were formed at room temperature. At higher temperatures (75 °C), complete deprotonation of the guanidino groups and formation of tetranuclear Zn alkyl complexes was observed, which feature low-coordinate zinc sites.
    Berichte der deutschen chemischen Gesellschaft 03/2012; 2012(8). DOI:10.1002/ejic.201101223


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