(Bu4N)[Re{NB(C6F5)3}Cl4(OH2)] – Struktur und EPR-Spektren

(Bu₄N)[Re{NB(C₆F₅)₃}Cl₄(OH₂)] – Structure and EPR Spectra The title compound represents the first structurally characterized rhenium(VI) complex with a bridging nitrido ligand. It has been prepared by the reaction of (Bu₄N)[ReNCl₄] with B(C₆F₅)₃ in CH₂Cl₂. An almost linear (170.5(3)°) nitrido bridge with a Re≡N bond length of 1.672(4) Å is formed. The coordination position trans to the multiple bond is occupied by a molecule of water. The EPR parameters of the title complex are reported and discussed with those of [ReNCl₄]^– concerning the spin-density distribution in the ‘‘ReNCl₄”︁”︁ unit.     

Synthesis of a novel bridged 2-(cyclopentadienyl)-indene system using Pd-catalyzed Negishi-type cross coupling

The palladium-catalyzed Negishi-type C-C-coupling of the nonaromatic systems 2-indenyl and cyclopentadienyl were investigated. The employed catalyst played a decisive role in product formation. Instead of Pd(PPh₃)₄, the more bulky Pd(dppf)Cl₂·CH₂Cl₂ led to the desired system in distinguished yields.     

Oligonary Nitrides and Oxonitrides of Si,P, Al,and B in Combination with Rare Earth or Transition Metals as well as Molecular Precursor Compounds with Nitrido Bridges M‐N‐Si (M = Ti,Zr, Hf,W, Sn)

A novel synthetic approach is presented leading to hitherto unknown nitridosilicates, oxonitridosilicates, oxonitridoaluminosilicates, carbidonitridosilicates, as well as nitridoborates and oxonitridoborates of rare earth elements, alkali, and alkaline earth metals. Typically, the respective metals were reacted with silicon diimide, aluminum nitride, or poly(boron amide imide), respectively, under pure nitrogen atmosphere utilizing a radiofrequency furnace. Usually, the compounds are obtained within short reaction periods as coarsely crystalline products. Zink nitridophosphates of the sodalite structure type were obtained by the reaction of phosphorus nitride imide with zinc or zinc chalcogenides, respectively. Several molecular metal silylamides and imides containing nitridobridges between the metals and silicon were obtained by the reaction of differently chlorinated disilazanes with metal chlorides. During these investigations hitherto unknown bis(trimethylsilyl)ammonium salts have been discovered. Furthermore, we report about the synthesis of N‐silyl metal hydrazides.     

Synthese und Struktur der Komplexe [(Me2PhP)3Cl2Re≡N‐RuCl2(C6H6)] und [(Me2PhP)3Cl2Re≡N‐RhCl(COD)]

Synthesis and Crystal Structure of the Complexes [(Me₂PhP)₃Cl₂Re≡N‐RuCl₂(C₆H₆)] and [(Me₂PhP)₃Cl₂Re≡N‐RhCl(COD)] The heteronuclear complex [(Me₂PhP)₃Cl₂Re≡N‐RuCl₂(C₆H₆)] ( 1 ) is obtained by the reaction of [ReNCl₂(PMe₂Ph)₃] with [RuCl₂(C₆H₆)]₂ in C₆H₅CN in form of red crystals with the composition 1 ·C₆H₅CN crystallizing in the monoclinic space group P2₁/c with a =1149.77(8), b = 3085.9(3), c = 1172.1(1) pm, β = 104.766(9)° and Z = 4. In the dinuclear complex the complex fragment [RuCl₂(C₆H₆)] is connected by an asymmetric nitrido bridge with the nitrido complex [ReNCl₂(PMe₂Ph)₃]. The nitrido bridge is characterised by a bond angle Re‐N‐Ru of 170.6(3)° and distances Re‐N = 170.2(5) and Ru‐N = 199.0(5) pm. The reaction of [ReNCl₂(PMe₂Ph)₃] with [RhCl(COD)]₂ in benzonitrile yields orange crystals of [(Me₂PhP)₃Cl₂Re≡N‐RhCl(COD)] ( 2 ) with the space group P2₁/c and a = 1522.3(2), b = 1274.85(4), c = 1921.2(2) pm, β = 106.759(7)° and Z = 4. The monovalent Rh atom exhibits a square planar coordination with the two π‐bonds of the cycloocta‐1, 5‐diene occupying cis positions. The distances in the almost linear nitrido bridge (Re‐N‐Rh = 174.8(4)°>) are Re‐N = 172.2(6) pm and Rh‐N = 195.6(6) pm.     

Use of ethyl oxamate for syntheses of oxamato(-1) and novel μ-oxamato(-2) complexes

Summary The use of ethyl oxamate for the synthesis of inorganic oxamato complexes is reported. A reaction system leading to the preparation of the novel polymeric -oxamato(-2) complexes [M(oxm)(H₂O)₂] _x (M=Cu, Zn, Cd), [Co(oxm)(H₂O)₂] _x ·0.5xH₂O and [Ni(oxm)(H₂O)₂] _x ·xH₂O is described (H₂ oxm = oxamic acid). Ethyl oxamate can also be used for the preparation of monomeric oxamato(-1) complexes.

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Der Einsatz von Ethyloxamat für die Synthese von Oxamato(-1) und neuen -Oxamato(-2)-Komplexen (Kurze Mitt.)

Zusammenfassung Es wird der Einsatz von Ethyloxamat für die Synthese von anorganischen Oxamato-Komplexen beschrieben. Ein Reaktions-System für die Herstellung von neuen -Oxamato(-2)-Komplexpolymeren: [M(oxm)(H₂O)₂] _x ; (M = Cu, Zn, Cd), [Co(oxm)(H₂O)₂] _x ·0.5xH₂O und [Ni(oxm)(H₂O)₂] _x ·xH₂O, wird vorgestellt. Ethyloxamat kann auch für die Herstellung von monomeren Oxamato(-1)-Komplexen verwendet werden.

     

Synthesis and characterization of binuclear transition metal–rhenium(VII) complexes with bridging cyanide ligands

Reacting transition metal complexes in low oxidation states, containing one or two cyanide ligands, with methyltrioxorhenium(VII) leads to bridged mixed metal compounds in good yields. The Re(VII) core is then surrounded by five or six ligands, respectively. The strength of these CN bridges and thus the stability of the newly generated bimetallic compound strongly depends on the donor strength of the ligands surrounding of the Cr/Mo/W or Fe moiety. The stability of the mixed metal molecules is reflected in the temperature dependent behavior of their ¹⁷O-NMR spectra, in their IR (Re=O) stretching frequencies and force constants, as well as several other spectroscopic data. UV–vis absorption spectra show the appearance of charge transfer bands. In the case of the mixed Mo/Re complexes the ⁹⁵Mo-NMR spectroscopy is also a helpful tool to examine the donor capability of the Mo moiety. The described compounds also show photosensitivity.     

Reactions of Rhenium and Technetium Nitrido Complexes with ER3 Fragments (E = B,Ga, Al,C, P; R = H,Alkyl, Aryl)

Terminal ‘N^3—’ ligands in rhenium and technetium nitrido complexes are sufficiently nucleophilic to react with Lewis acids under formation of nitrido‐bridged compounds. The reactivity of the nucleophilic centre and the nature of the formed compounds are strongly dependent on the Lewis acid and the composition of the metal complex used. Air‐stable compounds with Re≡N‐ER₃ bridges are formed when ER₃ is BR₃ (R = H, Cl, Br, Ethyl, Phenyl, C₆F₅), BCl₂Ph, GaCl₃, CPh₃⁺, or PPh₃. The six‐co‐ordinate rhenium(V) complexes [ReNX₂(PMe₂Ph)₃] (X = Cl, Br), [ReN(X)(Et₂dtc)(PMe₂Ph)₂] (Et₂dtc^— = diethyldithiocarbamate) and [ReN(Et₂dtc)₂(PMe₂Ph)] have been proved to be excellent starting materials for this type of reactions, whereas the five‐co‐ordinate precursors [ReNCl₂(PPh₃)₂], [ReN(Et₂dtc)₂], [ReN{Ph₂P(S)NP(S)Ph₂}₂] or [ReNCl₄]^— only react with the most reactive Lewis bases of the examples mentioned above such as BCl₂Ph or B(C₆F₅)₃. The rhenium‐nitrido bond lengths remain almost unchanged by the adduct formation, whereas a significant decrease of the trans‐influence of the nitrido complexes has been observed as can be seen by a shortening of the corresponding bond lengths or dimerization of five‐co‐ordinate precursors. Electrophilic attack of the Lewis acid to a donor atom of the equatorial co‐ordination sphere of the rhenium complex results in the formation of ‘underco‐ordinate’ metal centres which resemble to di‐, tri or tetrameric units with asymmetric nitrido bridges between each two rhenium atoms. EPR spectroscopy is an excellent tool to reflect the formation of nitrido bridges at the paramagnetic (d¹) [ReNX₄]^— core (X = F, Cl, Br, NCS). The spectral parameters derived for the products of reactions of [ReNCl₄]^— with various boron compounds indicate an increase of the covalency of the equatorial Re‐L bonds as a consequence of the formation of a nitrido bridge. The tendency for the formation of nitrido bridges with Lewis acids is significantly lower for technetium compounds compared to their rhenium analogues. Only a few examples with BH₃ and BPhCl₂ have been established.     

Synthese,Struktur und Eigenschaften der Komplexe [(H2O)Cl4Os≡N‐IrCl(C5Me5)(AsPh3)], [(Ph3Sb)Cl4Os≡N‐IrCl(C5Me5)(SbPh3)], [(Ph3Sb)2Cl3Os≡N‐IrCl(COD)] und [{(Me2PhP)2(CO)Cl2Re≡N}2ReNCl2(PMe2Ph)]

Synthesis, Crystal Structure, and Properties of the Complexes [(H₂O)Cl₄Os≡N‐IrCl(C₅Me₅)(AsPh₃)], [(Ph₃Sb)Cl₄Os≡N‐IrCl(C₅Me₅)(SbPh₃)], [(Ph₃Sb)₂Cl₃Os≡N‐IrCl(COD)] and [{(Me₂PhP)₂(CO)Cl₂Re≡N}₂ReNCl₂(PMe₂Ph)] The dinuclear complexes [(H₂O)Cl₄Os≡N‐IrCl(C₅Me₅)(AsPh₃)]·H₂O ( 1 ·H₂O), [(Ph₃Sb)Cl₄Os≡N‐IrCl(C₅Me₅)(SbPh₃)] ( 2 ), and [(Ph₃Sb)₂Cl₃Os≡N‐IrCl(COD)] ( 3 ) result from the reaction of the nitrido complexes [(Ph₃As)₂OsNCl₃] and [(Ph₃Sb)₂OsNCl₃] with the iridium compounds [IrCl₂(C₅Me₅)]₂ and [IrCl(COD)]₂ in dichloromethane. 1 crystallizes as 1 ·H₂O in form of green platelets in the monoclinic space group Cm and a = 1105.53(6); b = 1486.76(9); c = 2024.88(10) pm, β = 97.191(4)°, Z = 4. The formation of 1 in air involves a ligand exchange, and the coordination of a water molecule in trans position to the Os‐N triple bond. The resulting complex fragments [(H₂O)Cl₄Os≡N] and [IrCl(C₅Me₅)(AsPh₃)] are connected by an asymmetric nitrido bridge Os≡N‐Ir. The nitrido bridge is characterised by an Os‐N‐Ir bond angle of 173.7(7)°, and distances Os‐N = 168(1) pm and Ir‐N = 191(1) pm. 2 crystallizes in clumped together brown platelets with the space group and a = 1023.3(3), b = 1476.2(3), c = 1872.5(6) pm, α = 74.60(2), β = 73.84(2), γ = 76.19(2)°, Z = 2. In 2 the asymmetric nitrido bridge Os≡N‐Ir joins the two complex fragments [(Ph₃Sb)Cl₄Os≡N] and [IrCl(C₅Me₅)(SbPh₃)], which are formed by a ligand exchange reaction. 3 forms dark green crystals with the triclinic space group and a = 1079.4(1), b = 1172.3(1), c = 1696.7(2) pm, α = 101.192(9),β = 92.70(1), γ = 92.61(1)°, Z = 2. The distances in the almost linear nitrido bridge (Os≡N‐Ir = 175.3(7)°) are Os‐N = 171(1) pm and Ir‐N = 183(1) pm. The reaction of [ReNCl₂(PMe₂Ph)₃] with [Mo(CO)₃(NCMe)₃] unexpectedly affords the trinuclear complex [{(Me₂PhP)₂(OC)Cl₂Re≡N}₂ReNCl₂(PMe₂Ph)] ( 4 ) as the main product. It forms triclinic brown crystals with the composition 4 ·2THF and the space group (a = 1382.70(7), b = 1498.58(7), c = 1760.4(1) pm, α = 99.780(7), β = 99.920(7), γ = 114.064(6)°, Z = 2). In the trinuclear complex, the central fragment, [ReNCl₂(PMe₂Ph)] is joined in trans position to two nitrido complexes [(Me₂PhP)₂(CO)Cl₂Re≡N], giving an almost linear Re≡N‐Re‐N≡Re arrangement. The bond angles and distances in the nitrido bridges are Re‐N‐Re = 167.8(3)°, Re‐N = 171.1(8) pm and 204.2(8) pm; and Re‐N‐Re = 168.1(4)°, Re‐N = 170.9(9) and 203.5(9) pm respectively. As expected, the Re‐N bond length to the terminal nitrido ligand on the central Re atom is much shorter at 161.2(9) pm than the triple bonds of the asymmetric bridges.     

Synthese und Molekülstrukturen von amido‐ und imidoverbrückten Clustern elektronenreicher Übergangsmetalle

Synthesis and Structures of Amido‐ and Imidobridged Clusters of Electron‐rich Transition Metals We report in this article the results, which could be obtained within the DFG‐Project “Nitridobrücken zwischen Übergangsmetallen und Hauptgruppenelementen”. Reactions of electron‐rich transition metal compounds with either stannylated or lithiated amine derivatives lead in the presence of phosphines in different organic solvents to the formation of a large amount of nitrogenbridged transition metal clusters. The structures of 1 — 27 have been characterized by single crystal X‐ray‐structure analysis.     

Aluminiumorganic compounds of some metaldioximates

Coordinated dioximes with nickel(II), palla‐dium(II) and copper(II) ions proved capable of giving substitution reactions with a series of aluminiumorganic compounds. Studies made on the reaction products have revealed that in the case of both dimethylglyoxime and diphenylglyoxime. The reaction products result from substitution of the O? H…O hydrogen bridges existing in such compounds by O? Al? O bridges. All compounds reported in this paper were separated from the reaction mixture as coloured powders and were characterized by chemical analyses, IR spectroscopy, X‐ray diffraction spectra, proton NMR spectra and magnetic properties. Copyright © 2001 John Wiley & Sons, Ltd.