Biomedical subjects
Publications and source records attributed to Klaus Merz.
The title compounds are enantioselectively synthesized in just two preparative steps, making use of the Ugi-four-component reaction with an amino acid as chiral component, followed by a gold-catalyzed hydroamination.
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The title compound, [Hf(C11H23N2)2Cl(2)], is a monomeric hafnium(IV) complex containing two bidentate amidinate ligands and two cis Cl atoms. The crystals are triclinic (space group P-1) and there is one independent six-coordinate monomer with a highly distorted octahedral geometry in the asymmetric unit. The reported structure is the first hafnium-amidinate complex to be characterized successfully by single-crystal X-ray diffraction.
Cryptands bearing an intraannular azido substituent have been synthesized and characterized spectroscopically. Their complexation properties were investigated by picrate extraction analysis. The oxygen-containing cryptands were found to be good ligands for alkali cations, with a preference for Li(+) and Na(+). The molecular structure of the complex with KBr was determined by X-ray crystallography. In this, the first structurally characterized complex of an aryl azide bound to a metal cation, the potassium cation was found to show ninefold coordination to four oxygen atoms and two nitrogen atoms of the crown ether moiety, to the bromide anion and to N1 of the azido group, as well as C1 of the benzene ring.
New fascinating electronic features of the simple diketoamine chelate ligand HN[CH2C(tBu)=O]2 (1) are described. Unexpectedly, the corresponding trianionic amido-dienolate form of 1 is capable of reducing main-group metal atoms M after initial coordination and intramolecular L-->M two-electron transfer and of stabilizing main-group elements in unusual low oxidation states. This is impressively shown by the synthesis and structural characterization of the novel Ge and Sn complexes 4-6 by redox reactions of lithiated 1 with the corresponding metal halides GeCl4 and MCl2 (M=Ge, Sn). Surprisingly, conversion of tris-lithiated 1 with GeCl4 readily consumes two molar equivalents of GeCl4 and results in the formation of the neutral GeCl3 complex 4 and GeCl2. The former represents the second example of a structurally characterized neutral octahedrally coordinated germanium compound. Reaction of dilithiated 1 with GeCl2 does not lead to the expected ClGe(+2) complex but affords the novel dimeric germylene 5, whereas similar reaction using SnCl2 furnishes the monomeric stannylene (ClSn(+2) complex) 2 and elemental tin due to the higher oxidation potential of Sn(+2). Unexpectedly, a similar redox reaction of dilithiated 1 with PbCl2 furnishes the first air- and water-stable lithium 1,2-diketoimine-enolate 7 and elemental lead. Compound 7 is tetrameric in the solid state and consists of a strongly distorted Li4O4 cubic core with trigonal-bipyramidal coordinated Li+ ions.
Lithiation of the N-benzyl substituted diketoamine ligand PhCH(2)-N[CH(2)C(tBu=O](2) with lithium diisopropylamide (LDA) affords a novel chiral anionic N,O-ligand L; LiL reacts with GeCl(2).dioxane to give the corresponding new monomeric germylenes LGeCl and L(2)Ge.
Monophosphanylation of the difluorostannane Is2SnF2 (Is = 2,4,6-triisopropylphenyl) with Si(PH2)4 furnishes the first isolable fluoro(phosphanyl)stannane Is2Sn(F)PH2 1, which readily undergoes unique SiO2-assisted decompostion to [Is2Sn(PH)]2 2 and HF, while further phosphanylation of 1 leads to the remarkably stable diphosphanylstannane Is2Sn(PH2)2 3; the latter reacts with Me3SnF at the glass-wall to give the first perstannylphosphonium pentafluorosilicate [P(SnMe3)4]+ SiF5- 4.
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[structure: see text] The unprecedented formation of a complex macrocyclic selenium-carbon ring system, which is initiated by the action of coordinating reagents upon a sterically hindered alkynylselenolate, has been observed. The crystal structure of the product could be obtained and shows a rigid tricyclic arrangement consisting only of selenium and sp(2)-hybridized carbon atoms. This reactivity stands in contrast to the corresponding unsubstituted alkynylselenolates and is an example where a bulky substituent destabilizes an adjacent unsaturated pi-system.
The crystal packing of 1-iodo-3-nitrobenzene, C(6)H(4)INO(2), is formed by planar molecules which are linked by I...I and NO(2)...NO(2) interactions. In the case of 1-iodo-3,5-dinitrobenzene, C(6)H(3)IN(2)O(4), the NO(2) groups are not exactly coplanar with the benzene ring and the molecules form sheets linked by NO(2)...NO(2) interactions. In contrast with 4-iodonitrobenzene, the crystal structures of both title compounds do not form highly symmetrical I...NO(2) intermolecular interactions.
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Single crystals of germanium(IV) tetrachloride, GeCl(4), were grown at 193 K. In the crystal structure, the isolated molecules have very well realised tetrahedral geometry.
The title compound, C(6)H(13)O(3)P, displays a crystallographic mirror plane. Bond lengths in the phosphonic acid moiety are P[double bond]O = 1.5557 (13) A and P[double bond]O = 1.5089 (18) A. The molecules are linked via intermolecular hydrogen bonding to form a one-dimensional chain of fused rings. There are no significant contacts between planes.
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