Martin Gärtner

Friedrich-Schiller-University Jena, Jena, Thuringia, Germany

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Publications (24)73.58 Total impact

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    ABSTRACT: Starting material KN(H)C(6)H(3)-2,6-F(2) was prepared via a transamination reaction from KNH(2) and 2,6-F(2)C(6)H(3)NH(2) in THF and crystallized from 1,4-dioxane (diox) as the three-dimensional polymer [(diox)(1.5)K{N(H)-2,6-F(2)C(6)H(3)}.diox(0.5)](infinity) (1). The metathesis reaction of (THF)(4)CaI(2) with KN(Me)Ph in THF yields monomeric (THF)(4)Ca[N(Me)Ph](2) (2) with a nearly linear N-Ca-N moiety of 179.84(8) degrees . The metathesis reaction of (THF)(4)CaI(2) with KN(H)Mes yields trinuclear (THF)(6)Ca(3)[N(H)Mes](6) (3) with a linear Ca(3) fragment and bridging 2,4,6-trimethylphenylamido groups. The reaction of 1 with (THF)(4)CaI(2) gives dinuclear (THF)(5)Ca(2)[N(H)-2,6-F(2)C(6)H(3)](4).2THF (4) with three bridging and one terminally bound 2,6-difluorophenylamide. A similar reaction of (THF)(5)SrI(2) with KN(H)-2,6-F(2)C(6)H(3) yields dinuclear (THF)(6)Sr(2)[N(H)-2,6-F(2)C(6)H(3)](3)I.THF (5) in which the iodide anion binds terminally. This iodide ligand cannot be substituted as easily by excess KN(H)-2,6-F(2)C(6)H(3). The metathesis reaction of (THF)(5)BaI(2) with KN(H)-2,6-F(2)C(6)H(3) leads to the formation of [(THF)(2)Ba{N(H)-2,6-F(2)C(6)H(3)}(2)](infinity) (6) which crystallizes as a one-dimensional polymer with bridging 2,6-difluorophenylamide anions and additional Ba-F-bonds.
    Dalton Transactions 04/2008; DOI:10.1039/b717267b · 4.10 Impact Factor
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    ABSTRACT: The reaction of diethylmagnesium with diphenylphosphane yields [(THF)Mg(Et)PPh 2] infinity ( 1; THF = tetrahydrofuran) with bridging PPh 2 ligands and average Mg-P bond lengths of 262.2 pm. The metalation reaction of MgEt 2 with HPPh 2 and H 2PPh with a 1:2 stoichiometry gives [(THF) 4Mg(PPh 2) 2] ( 2) and [(THF) 6Mg 4{P(H)Ph} 8] ( 3), respectively. Tetranuclear 3 contains three chemically different phenylphosphanide groups with characteristic P-H stretching frequencies at 2261, 2286, and 2310 cm (-1). The metathesis reaction of potassium phenylphosphanide with CaI 2 yields oligomeric (THF) 3Ca[P(H)Ph] 2 ( 4). A similar reaction with SrI 2 and BaI 2 gives polymeric [(THF) 2Sr{P(H)Ph} 2] infinity ( 5) and [(THF)Ba{P(H)Ph} 2] infinity ( 6), respectively, showing one stretching frequency at 2285 cm (-1). These compounds crystallize polymeric with bridging phenylphosphanide substituents. The addition of Et 2O to a mixture of KPPh 2 and Mg(PPh 2) 2 in THF initiates the crystallization of (Et 2O)K[(THF)Mg(PPh 2) 3] ( 7) with a strand structure and (Et 2O) x(THF) yK 2[Mg(PPh 2) 4] ( 8) with a layer structure depending on the stoichiometry. The crystals of 8 easily lose THF and Et 2O and, therefore, the content of these ethers varies. Recrystallization of 8 from hot 1,4-dioxane (diox) yields (diox) 2K 2[Mg(PPh 2) 4] ( 9) with a layer structure comparable to that of 8. The central structural units are eight-membered K 2Mg 2P 4 rings that are interconnected by P-K-P bridges. In a THF solution, the magnesiates 7- 9 dissociate into the homometallic derivatives KPPh 2 and Mg(PPh 2) 2, as can be seen from NMR experiments.
    Inorganic Chemistry 03/2008; 47(4):1397-405. DOI:10.1021/ic702148v · 4.79 Impact Factor
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    ABSTRACT: The direct synthesis of 1-naphthyliodide and -bromide with calcium powder yields (thf)4Ca(Naph)I (1) and [(thf)3Ca(Naph)Br]2 (2), respectively. The metathesis reaction of 1 with KN(SiMe3)2 gives (thf)3Ca(Naph)–N(SiMe3)2 (3). In 2 and 3 very small Ca–C bond lengths of 252.8(4) and 251.4(6) pm, respectively, are observed. These compounds slowly decompose in THF solution via ether cleavage reactions. From this degradation, [(thf)4CaBr2]·naphthalene (4) crystallizes from THF solutions. Furthermore, decomposition of 1 in THF solution yields ethene and naphthalene whereas intermediate ethenolate undergoes subsequent degradation to an acetylide.
    Journal of Organometallic Chemistry 01/2008; 693(2):221-227. DOI:10.1016/j.jorganchem.2007.10.038 · 2.30 Impact Factor
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    ABSTRACT: In the title compound, [CaI2(C4H8O)(C4H10O2)2], the Ca atom is situated in the centre of a distorted pentagonal bipyramid. Two iodide anions occupy the axial positions, whereas the five oxygen donor atoms of two molecules of 1,2-dimethoxyethane and one molecule of tetrahydrofuran occupy the equatorial positions. The molecule is located on a crystallographic C2 axis.
    Acta Crystallographica Section E Structure Reports Online 12/2007; 63(12). DOI:10.1107/S1600536807059399 · 0.35 Impact Factor
  • Acta Crystallographica Section E Structure Reports Online 12/2007; 63(12). DOI:10.1107/S1600536807059399/bt2622Isup2.hkl · 0.35 Impact Factor
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    ABSTRACT: Compounds of the type aryl--M--X, with M=Ca, Sr, Ba and X as any kind of ligand (such as halide, phosphanide, amide, aryl), are presented. The low reactivity of the heavy alkaline earth metals calcium, strontium, and barium enforces an activation prior to use for the direct synthesis. The insertion of these metals into C--I bonds of aryl iodides (direct synthesis) yields aryl metal iodides and has to be performed at low temperatures and in THF. Aryl alkaline-earth-metal compounds show some characteristics: 1) the ease of ether cleavage enforces low reaction temperatures, 2) for Sr and Ba the Schlenk equilibrium is shifted towards homoleptic MI2 and MPh2, 3) high solubility of diaryl alkaline-earth-metal derivatives in THF even at low temperatures initiated quantum chemical investigations on the aggregation behavior, and 4) a strong low field shift of the 13C resonances of the ipso carbon atoms in NMR spectra was observed. First results from quantum chemical calculations on diaryl dicalcium(I) suggest a long Ca--Ca bond with a considerable Ca--Ca bond dissociation energy. Initial results on a selection of applications such as metallation, metathesis, and addition reactions of aryl calcium compounds are presented as well.
    Chemistry 10/2007; 13(22):6292-306. DOI:10.1002/chem.200700558 · 5.70 Impact Factor
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    ABSTRACT: Several preparative procedures for the synthesis of the THF complexes of the alkaline earth metal bis(phenylamides) of Mg (1), Ca (2), Sr (3), and Ba (4) are presented such as metalation of aniline with strontium and barium, metathesis reactions of MI2 with KN(H)Ph, and metalation of aniline with arylcalcium compounds or dialkylmagnesium. The THF content of these compounds is rather low and an increasing aggregation is observed with the size of the metal atom. Thus, tetrameric [(THF)2Ca{mu-N(H)Ph}2]4 (2) and polymeric [(THF)2Sr{mu-N(H)Ph}2]infinity and {[(THF)2Ba{mu-N(H)Ph}2]2[(THF)Ba{mu-N(H)Ph}2]2}infinity show six-coordinate metal atoms with increasing interactions to the pi systems of the phenyl groups with increasing the radius of the alkaline earth metal atom.
    Inorganic Chemistry 10/2007; 46(18):7678-83. DOI:10.1021/ic7010524 · 4.79 Impact Factor
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    ABSTRACT: The metathesis reaction of CaI2 with KPPh2 in THF yields (thf)4Ca(PPh2)2 (1). A metallation of HPPh2 with alkaline earth metals succeeds with strontium and barium and gives (thf)4Sr(PPh2)2 (2) and (thf)5Ba(PPh2)2 (3). From crystal structure determinations of 1 and 2 Ca-P and Sr-P bond lengths of 298.65(6) and 314.29(9) pm, respectively, were obtained. Extremely large Ba-P distances of 332.8(2) and 334.5(2) pm were found for 3. In order to investigate the influence of the bulkiness of the phosphanides on the molecular structure, (thf)4Ba[P(Mes)2]2 (4) and (thf)2Ba[P(Et)Ph]2 (5) were prepared in a similar manner. Derivative 4 is monomeric with Ba-P distances of 318.72(9) pm, whereas 5 crystallizes as a one-dimensional polymer with bridging ethyl(phenyl)phosphanide groups with Ba-P bond lengths between 324.8(1) and 336.0(1) pm.
    Zeitschrift für anorganische Chemie 09/2007; 633(11‐12):2025 - 2031. DOI:10.1002/zaac.200700256 · 1.25 Impact Factor
  • Acta Crystallographica Section E Structure Reports Online 09/2007; 63(9). DOI:10.1107/S1600536807037427/bt2446Isup2.hkl · 0.35 Impact Factor
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    ABSTRACT: The title compound, {[K(C12H10N)(C4H8O2)2]·C4H8O2}n, contains a K atom surrounded by two bridging diphenylamido ligands and three molecules of dioxane. Two of these dioxane ligands are located on a centre of inversion and form bridges to neighbouring K atoms, yielding two-dimensional layers. The K atom is in a distorted square-pyramidal environment in which one bridging dioxane molecule occupies the apical position.
    Acta Crystallographica Section E Structure Reports Online 09/2007; 63(9). DOI:10.1107/S1600536807037427 · 0.35 Impact Factor
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    ABSTRACT: Copper(II) and nickel(II) complexes with the new Schiff-base ligands N-salicylidene-3-(2-pyridyl)-propionic acid hydrazide (H2salhypyp) and the newly synthesized N-Salicylidene-3-(1-benzylimidazol-2-yl)-propionic acid hydrazide (H2salhyimp) have been synthesized and structurally characterized. The crystal structure analysis of the metal complexes reveals two fundamentally different structural motifs. Cationic di-μ-phenolate-bridged dimers are observed for the complexes with the H2salhypyp ligand, [{Cu(H2salhypyp)(MeOH)(ClO4)}2](ClO4)2 (1) and [{Ni(H2salhypyp)Cl(MeOH)}2]Cl2(MeOH)2 (2), whereas neutral dimeric units aggregated via the side chain nitrogen donors are observed for the complexes with the H2salhyimp ligand, [{Ni(salhyimp)}2](H2O)4 (4) and [{Cu(salhyimp)}2](MeOH)4 (3). The formation of either motif depends on the charge of the ligand species and consequently on the pH-value of the reaction solution. For the complexes 1 and 2 extensive hydrogen-bonding networks are observed which involve the perchlorate (N–H···O–Cl) and chloride anions (N–H···Cl), respectively. The M2O2 core unit of complexes 1 and 2 facilitates the formation of intramolecular M–(Me)O–H···X–M hydrogen-bonding interactions . The copper complex 3 exhibits an unusual one-dimensional coordination polymer which is linked through the axial coordination of phenolate oxygen atoms of adjacent dimeric units. Complex 4 exhibits a layered structure with each layer composed of hydrophobic π-stacks of the dimeric complex units which are interlaced by hydrogen-bonded chains of water molecules. The supramolecular structures of 3 and 4 are governed by π-π-stacking interactions. For 4 additional CH/π interactions are found within and between individual sheets of the layered structure.
    Zeitschrift für anorganische Chemie 09/2007; 633(11‐12):2009 - 2018. DOI:10.1002/zaac.200700249 · 1.25 Impact Factor
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    ABSTRACT: The title compound, [K2(C4H8O)6(C12H10N)2], contains two K atoms which are coordinated by two bridging diphenylamide ligands to yield a centrosymmetric four-membered KNKN ring. Each K atom is additionally coordinated by three molecules of tetrahydrofuran, yielding a square pyramid in which one tetrahydrofuran molecule occupies the apical position. One CH2 group and four H atoms are disordered equally over two positions.
    Acta Crystallographica Section E Structure Reports Online 09/2007; 63(9). DOI:10.1107/S1600536807037439 · 0.35 Impact Factor
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    ABSTRACT: A general procedure for the synthesis of a wide variety of arylcalcium halides by activation of the alkaline earth metal as well as bromo- or iodoarenes is reported. Chloro- and fluoroarenes are not suitable substrates for an insertion of calcium into the carbon-halogen bond. Furthermore, ortho-fluoro substitution prevents the formation of the corresponding heavy calcium organometallics. The ipso-carbon atoms show a strong low-field shift in the C-13 NMR spectra. The arylcalcium iodides crystallize monomeric as tetrakis(THF) complexes. Naphthylcalcium iodide shows a Ca-C bond length of 255.2(6) pm which lies in the characteristic region.
    ChemInform 07/2007; 2007(5):725-730. DOI:10.1055/s-2007-965909
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    ABSTRACT: Various preparative procedures are employed in order to synthesize alkaline earth metal bis(diphenylamides) such as (i) metalation of HNPh2 with the alkaline earth metal M, (ii) metalation of HNPh2 with MPh2, (iii) metathesis reaction of MI2 with KNPh2, (iv) metalation of HNPh2 with PhMI in THF, and (v) metathesis reaction of PhMI with KNPh2 followed by a dismutation reaction yielding MPh2 and M(NPh2)2. The magnesium compounds [(diox)MgPh2]infinity (1) and (thf)2Mg(NPh2)2 (2) show tetracoordinate metal atoms, whereas in (dme)2Ca(NPh2)2 (3), (thf)4Sr(NPh2)2 (4), and (thf)4Ba(NPh2)2 (5) the metals are 6-fold coordinated. Additional agostic interactions between an ipso-carbon of one of the phenyl groups of the amide ligand and the alkaline earth metal atom lead to unsymmetric coordination of the NPh2 anions with two strongly different M-N-C angles in 3-5.
    Inorganic Chemistry 07/2007; 46(12):5118-24. DOI:10.1021/ic700459d · 4.79 Impact Factor
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    ABSTRACT: The Schiff base-type title compound, C15H15N3O2, was obtained by the reaction of 3-(2-pyridyl)propionohydrazide with salicylaldehyde in ethanol. Whereas the 1H NMR spectrum in solution points to a mixture of two isomers, only one isomer was found in the solid state. The phenolic OH group forms an intramolecular hydrogen bond with the imino N atom. Intermolecular hydrogen bonds between the amido NH function and the pyridyl N atom join the molecules into chains parallel to the a axis. The compound is achiral, but crystallizes in the space group P212121, with the molecule adopting a chiral conformation.
    Acta Crystallographica Section E Structure Reports Online 07/2007; 63(7). DOI:10.1107/S1600536807025664/gk2074Isup2.hkl · 0.35 Impact Factor
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    ABSTRACT: Organocalcium chemistry is still in its infancy. The direct synthesis of activated calcium and (substituted) iodobenzenes allows for the large-scale and high-yield synthesis of aryl calcium iodides. The influence of the substitution patterns of the phenyl group, halogen atom, and solvent is discussed. Aryl calcium iodides show a Schlenk equilibrium that enables the isolation of diaryl calcium derivatives. Owing to the high reactivity of aryl calcium halides, low temperatures have to be maintained throughout the preparative procedures in order to avoid side reactions. A decrease of reactivity and, hence, an enhanced stability at higher temperatures can be achieved by shielding of the calcium atom by increasing the coordination number of the metal center or by substitution of the iodide anion by bulky groups.
    Angewandte Chemie International Edition 06/2007; 46(12):1950-6. DOI:10.1002/anie.200604192 · 11.34 Impact Factor
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    ABSTRACT: Die Organocalciumchemie steht noch immer am Anfang ihrer Entwicklung. Die Direktsynthese aus Iodarenen und aktiviertem Calciumpulver eröffnet einen einfachen Zugang zu Arylcalciumiodiden in guten Ausbeuten. Der Einfluss des Substitutionsmusters der Phenylgruppe, des Halogens und des Lösungsmittels wird diskutiert. Die Arylcalciumhalogenide zeigen ein Schlenk-Gleichgewicht, das die Isolierung von Diarylcalciumderivaten ermöglicht. Wegen der hohen Reaktivität der Arylcalciumhalogenide müssen während der Herstellung und Handhabung tiefe Temperaturen aufrechterhalten werden. Eine geringere Reaktivität und höhere Beständigkeit können durch sterisches Abschirmen des Calciumatoms erreicht werden, z. B. durch Erhöhung der Koordinationszahl des Metallzentrums oder Substitution des Iodidions durch sperrige Gruppen.
    Angewandte Chemie 03/2007; 119(12):1994 - 2001. DOI:10.1002/ange.200604192
  • Angewandte Chemie 02/2007; 119(10):1642-1647. DOI:10.1002/ange.200604436
  • Angewandte Chemie International Edition 02/2007; 46(10):1618-23. DOI:10.1002/anie.200604436 · 11.34 Impact Factor
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    ABSTRACT: The metathesis reactions of (thf)4Ca(Ph)I with the corresponding potassium compounds KR yield the heteroleptic arylcalcium derivatives (thf)3Ca(Ph)[N(SiMe3)2] (1) and (thf)4Ca(Ph)PPh2 (2), due to the insolubility of KI in common organic solvents. However, the reaction of KCp and KOC6H2-2,6-tBu-4-Me with (thf)4Ca(Ph)I give the homoleptic compounds (thf)2CaCp2 (3) and (dme)CaCp2 (4) (depending on the solvent) as well as (thf)3Ca(OC6H2-2,6-tBu-4-Me)2 (5). Diphenylcalcium decomposed under these reaction conditions. The reaction of K[(Me3SiN)2CPh] with (thf)4Ca(Ph)I yields [{(thf)3Ca}2{4,4-Ph2-2,6-(C6H4)2C3N3}(μ-I)] (6). This dihydrotriazine derivative forms due to a slow liberation of benzonitrile from the starting N,N'-bis(trimethylsilyl)benzamidinate. A solvent change in order to shift the Schlenk equilibrium (2 PhCaICaPh2 + CaI2) toward the homoleptic diphenylcalcium leads immediately to ether cleavage reactions and the formation of [{(Et2O)CaPh2}4·(Et2O)CaO] (7), which precipitates from diethyl ether. This cage compound contains an oxygen-centered Ca5 square pyramid with the phenyl groups bridging all Ca···Ca edges.
    Organometallics 01/2007; 26(4). DOI:10.1021/om061021q · 4.25 Impact Factor