bluuebunny/crossref_metadata_2025_split huggingface dataset:
Complete Nitrogen Coordination in Rare Earth Bipyridine Pyrrolate Complexes from Pyrrole under Solvothermal Conditions: [Ln(Pyr)3(Bipy)2], Ln = Pr, Yb
Authors: Quitmann Catharina C. , Müller‐Buschbaum Klaus 
Published: October 2005

AbstractThe compounds [Ln(Pyr)3(Bipy)2], Ln = Pr (1), Yb (2), (Pyr– = pyrrolate anion, C4H4N−; Bipy = 2,2′‐bipyridyl, C10H8N2) were obtained by the solvothermal reaction of pyrrole with praseodymium and ytterbium metal and the amine bipyridine. Yellow‐green single crystals of 1 and yellow crystals of 2 are formed next to dark green solutions. 1 and 2 are isotypic and exhibit monomeric molecules with a complete nitrogen coordination of three pyrrolate anions and two bipyridine molecules around the trivalent rare earth ions. Thus co‐coordination with Bipy renders unsubstituted pyrrolates of the rare earth elements feasible from solvothermal conditions in addition to previous low‐temperature syntheses. The products were investigated by X‐ray single crystal diffraction, Mid IR and Far IR spectroscopy.
Synthesis and X‐ray Structure of n‐Propylimidodiphosphonic Anhydride, a New Precursor for the Hydrothermal or Solvothermal Synthesis of Zinc Phosphates
Authors: Chivers Tristram , Fu Zhiyong , Grebinski James , Parvez Masood 
Published: October 2005

Abstractn‐Propylimidodiphosphonic anhydride [O(OH)P(μ‐O)PO(OH)(μ‐NnPr)]2·2NH2nPr (1) is prepared by hydrolysis of trichloro‐n‐propylimidophosphorane with three equivalents of water. X‐ray analysis shows that 1 forms an eight‐membered P4N2O2 ring in a chair conformation. These heterocycles are linked via extensive hydrogen‐bonding to form a three‐dimensional network. Hydrothermal reactions of 1 with zinc chloride give rise to P‐N bond cleavage and the formation of the hydrated zinc phosphates, {Zn3(PO4)2·H2O}n and {Zn3(PO4)2·4H2O}n, whereas the solvothermal reaction in isopropyl alcohol produces the anionic network [ZnCl(HPO4)−]n with [nPrNH3]+ counter‐ions.
Über die Umsetzung von (TAS)+[P4N4F9]− mit Me3SiCF3
Authors: Kingston Melanie , Lork Enno , Mews Rüdiger 
Published: October 2005

AbstractOn the Reaction of (TAS)+[P4N4F9]− with Me3SiCF3From the reaction of (TAS)+[P4N4F9]− with Me3SiCF3 in CH3CN (TAS+)2[{NP(CF3)2F}(NPF2)2{NP(N‐C≡C‐SiMe3)F}]2− (1) was isolated and characterized by X‐ray crystallography. The by‐products (TAS+)2 [{NP(CF3)2F}(NPF2)2{NP(CF3)(N‐C≡C‐SiMe3)}]2− (2) and (TAS+) [{NP(CF3)2F}(NPF2)3]− (3) were identified by nmr spectroscopy. In the reaction described, Me3SiCF3 reacts in the presence of fluoride ions towards the phosphazene as trifluoromethylating‐, towards the solvent CH3CN as deprotonating‐ and silylating reagent.
Organoplatinum Complexes of the N,N‐Diisopropyl‐diazabutadiene Ligand: A Structural and Spectroscopic Study
Authors: Klein Axel , Schurr Thilo , Záliš Stanislav 
Published: October 2005

AbstractOrganoplatinum complexes [Pt(R)2(iPr‐DAB)], [PtCl(R)(iPr‐DAB)] or [PtCl2(iPr‐DAB)] (R = methyl or 2,4,6‐trimethylphenyl = mesityl, iPr‐DAB = N,N′‐diisopropyl‐1,4‐diazabutadiene) have been investigated by a combination of multiple spectroscopy (NMR, UV/VIS), single crystal XRD and quantum chemical calculations. Excellent agreement of calculated and experimental structural data from XRD or NMR provide a good basis for the quantum mechanical calculations. DFT calculations reveal the contributions of the DAB ligand and the co‐ligands to the electronic ground state. Methyl acts more or less purely as a σ‐donor, Cl or mesityl provide strong contributions (p or π) to the highest occupied molecular orbital (HOMO) whereas the lowest unoccupied molecular orbital (LUMO) is mainly centred to the DAB ligand. The TD‐DFT calculated electronic transitions were in excellent agreement with the experimental ones and allow reliable assignment of the absorption bands.
Mononuclear Metal Phosphinates with Ancillary Pyrazole Ligands. Synthesis and X‐ray Crystal Structures of [M(Ph2PO2)2(3,5‐DMPZ)2] (M = Co, Zn)
Authors: Chandrasekhar Vadapalli , Boomishankar Ramamoorthy , Sasikumar Palani , Nagarajan Loganathan , Cordes A. Wallace 
Published: October 2005

AbstractThe reaction of diphenylphosphinic acid, [Ph2P(O)(OH)], with CoCl2 or ZnCl2 and 3,5‐dimethylpyrazole (DMPZ) in the presence of triethylamine affords the mononuclear phosphinates, M(Ph2PO2)2(DMPZ)2 (M= Co(1), Zn(2)). The molecular structures of 1 and 2 reveal a tetrahedral environment around the metal. The phosphinate ligands are monoanionic and bind to the metal in a monodentate manner, while the pyrazole ligands act as neutral monodentate ligands. Intermolecular C‐H‐O and π–π interactions in 1 and 2 result in the generation of two dimensional supramolecular polymeric sheets in the solid state.
2‐Amino‐substituted 1,3,2‐Diazaphospholenes
Authors: Burck Sebastian , Gudat Dietrich , Lissner Falk , Nättinen Kalle , Nieger Martin , Schleid Thomas 
Published: October 2005

Abstract2‐Amino‐substituted 1,3,2‐diazaphospholenes 2 ‐ 4 were synthesised by treatment of 1,3‐dimesityl‐2‐chloro‐1,3,2‐diazaphospholene with one equivalent of lithium N,N′‐dimesityl‐2,4‐pentanedioniminate, sodium amide, or a mixture of 3,5‐diphenylpyrazole and NEt3. In contrast, 1,3‐di‐tert.butyl‐1,3,2‐diazaphospholene reacted with sodium amide in a 2:1 molar ratio to afford the bis‐diazaphospholenyl‐imine 5. All products were characterised by spectroscopic data and single‐crystal X‐ray diffraction studies. Evaluation of trends in bond lengths suggest the presence of similar residual π‐delocalisation effects as had previously established in P‐Cl or P‐H substituted diazaphospholenes but disclosed that 2 ‐ 5 differ from these compounds in lacking all signs for a concomitant lengthening of the exocyclic P‐X bonds. The results of computational studies allowed to conclude that the deviating behaviour of diazaphospholenes with different P‐X substituents is attributable to a shift in the balance between n(N)→σ*(P‐X)‐ and n(X)→σ*(P‐N)‐hyperconjugation interactions.
The Simple Hexapyridine Cluster [Mo6Br8Py6][OSO2CF3]4 and Substituted Hexapyridine Clusters Including a Cluster‐cored Polyolefin Dendrimer
Authors: Méry Denise , Plault Lauriane , Nlate Sylvain , Astruc Didier , Cordier Stéphane , Kirakci Kaplan , Perrin Christiane 
Published: October 2005

AbstractThe yellow octahedral molybdenum cluster [n‐Bu4N]2[Mo6Br8(CF3SO3)6], (1); undergoes substitution of all six terminal triflate ligands by pyridine ligands in pyridine/THF at 60 °C to yield the orange hexapyridine cluster [Mo6Br8(Py)6][CF3SO3]4, (2). The cluster 1 also reacts in THF at 60 °C with excessof the para‐substitued pyridines 4‐tert‐Bupy and 4‐vinylpy to give the orange para‐substituted hexapyridine clusters [Mo6Br8(p‐Py‐R)6][CF3SO3]4 (3: R = tert‐Bu; 4: R = vinyl) and with the new dendronic pyridine derivative 3,3′‐{CH2Op‐C6H4C(CH2CH=CH2)3}2Py, (5) (7 d), to give the orange relatively air stable Mo6‐cluster‐cored 36‐allyl dendrimer [Mo6Br8(3,5‐{CH2OC6H4C(CH2CH=CH2)3}2Py)6][CF3SO3]4, (6). All these substitution reactions were easily monitored by 1H NMR in CDCl3 using the comparison between the intensities of the tetrabutylammonium cation and deshielded coordinated pyridine signals.
Pentahydrido‐, Trihydrido‐ und Dihydrido‐Iridiumkomplexe mit bifunktionellen Phosphanen als Liganden
Authors: Steinert P. , Werner H. 
Published: October 2005

AbstractPentahydrido‐, Trishydrido‐, and Bishydridoiridium Complexes with Bifunctional Phosphanes as LigandsThe pentahydridoiridium(V) complexes [IrH5{κ(P)‐iPr2PX}2] (4‐6) with X = CH2CO2Me, (CH2)2OMe and (CH2)3NMe2 were prepared from iridium(I) or iridium(III) precursors and hydride donors such as NaBH4 or LiAlH4. While attempts to obtain the iridium(III) compounds [IrH3(iPr2PX)2] failed, the complex [IrH3(CO){κ(P)‐iPr2PCH2CO2Me}2] (7) was formed from 4 and CO. The reactions of 4‐6 with acetic acid led, by elimination of two equivalents of H2, to the bishydrido compounds [IrH2(κ2‐O2CCH3){κ(P)‐iPr2PX}2] (8‐10), which are rigid in solution. In contrast, the corresponding complex [IrH2(κ1‐O2CCF3){κ(P)‐iPr2PCH2CO2Me}{κ2‐(P,O)‐iPr2PCH2CO2Me}] (11) is fluxional in solution, the trifluoracetato ligand, however, being not involved in the change of the hapticity.
Thioether Functionalized Pyrazolate Ligands and their Dicopper(II) Complexes – Structures and Magnetic Properties
Authors: Teichgräber Jörg , Leibeling Guido , Dechert Sebastian , Meyer Franc 
Published: October 2005

AbstractA bis(bidentate) compartmental pyrazolate ligand HL with appended methylthiomethyl substituents in the 3‐ and 5‐positions of the heterocycle has been synthesized. It forms doubly pyrazolato bridged dicopper(II) complexes [L2Cu2]X2 (X = NO3− (3a), ClO4− (3b)) with the metal ions in square planar {S2N2} environment and additional weak axial interactions with the respective counteranions. Magnetic measurements reveal strong antiferromagnetic coupling with J = −243 or −231 cm−1 (Ĥ = −2J·S1S2), which is at the upper limit of what has previously been observed for bis(μ‐pyrazolato)dicopper(II) complexes.
Synthesis and Characterization of the Novel AlI Compound Al(C5Me4Ph): Comparison of the Coordination Chemistry of Al(C5Me5) and Al(C5Me4Ph) at d10 Metal Centers1)
Authors: Buchin Beatrice , Steinke Tobias , Gemel Christian , Cadenbach Thomas , Fischer Roland A. 
Published: October 2005

AbstractThe synthesis of the novel AlI compound AlCp*Ph (Cp*Ph = C5Me4Ph) is presented. This compound is characterized by 1H, 13C, 27Al NMR spectroscopy, elemental analysis as well as its reactivity towards the α,ω‐diolefin dvds (dvds = tetramethyl‐divinyl‐disiloxane). Also the reactivity of AlCp* towards dvds is investigated and the product [(dvds)(μ2‐AlCp*)2] characterized by NMR spectroscopy, elemental analysis as well as X‐ray crystallography. Furthermore, two new coordination compounds of AlCp* to d10 metal centers are synthesized and characterized. [Pd(AlCp*)4] is obtained by reaction of [(tmeda)PdCl2] with AlCp*, and [Ni(AlCp*)4] is synthesized from [Ni(cod)2] and AlCp* via ligand substitution. Both complexes are spectroscopically and crystallographically characterized. Finally, preliminary results on the coordination of AlCp*Ph to Ni0 and Pd0 centers will be discussed.
Polymer Two‐Dimensional Networks of Au55 Clusters
Authors: Schmid Günter , Vidoni Olivia , Torma Viktoria , Pollmeier Klaus , Rehage Heinz , Vassiliev Andrei 
Published: October 2005

AbstractMonolayers and thin films of Au55 clusters, linked by different dithiol spacer molecules and by polymerization between functionalized ligands, were prepared and investigated by TEM and AFM. Due to spacer molecules of different lengths, the cluster‐cluster distances could be varied from 1.3 up to 3.8 nm, enabling later investigations of electron transport processes in two dimensions. Film formation was carried out using either Langmuir‐Blodgett techniques or spin‐coating processes in the presence of the spacer molecules. Polymerization reactions between neighboured clusters in monolayers or thin films succeeded by the use of vinyl‐substituted ligand molecules. (Vinyl)8Si8O11(OH)2 and p‐styryl‐diphenylphosphine modified Au55 clusters could be linked by light‐induced polymerization via the vinyl functions.
Copper(I) Chloride Cluster Complexes with Pentaphenyl‐Cyclopentaphosphane as Ligand
Authors: Scherer Markus , Stein Daniel , Breher Frank , Geier Jens , Schönberg Hartmut , Grützmacher Hansjörg 
Published: October 2005

AbstractPentaphenylcyclopentaphosphane, c‐(P5Ph5) is conviently prepared from PhPCl2 and thermally activated zinc powder in thf. Hydrolysis of c‐(P5Ph5) in the presence of ZnCl2 gives to an equimolar distribution of PhPH2, PhP(=O)H2, and PhP(=O)(OH)H. Reaction of c‐(P5Ph5) with CuICl leads to the tetranuclear copper(I) chloride complex [Cu4(μ4‐Cl)2(μ2‐Cl)2{c‐(P5Ph5)}2] with a Cu4(μ4‐Cl)2(μ2‐Cl)2 cluster core and the hexanuclear [Cu6(μ3‐Cl)2(μ2‐Cl)2{c‐(P5Ph5)}2(thf)2]. Hydrolysis of the copper c‐(P5Ph5) complexes leads to significantly higher amounts of the primary phosphane oxide PhP(=O)H2.
First Examples of Metal Cyclohexylphosphonates: Influence of the Choice of Synthetic Route on the Product
Authors: Murugavel Ramaswamy , Davis Paul , Walawalkar Mrinalini G. 
Published: October 2005

AbstractThe first divalent metal cyclohexylphosphonate derivative, [Co(O3PCy)·H2O]n (1) has been synthesized using four different synthetic methodologies in the presence of added amines. The new phosphonates have been characterized with the aid of analytical, thermoanalytical, spectroscopic, and powder XRD studies. The nature and particle size of the product formed is highly dependent on the method employed (viz. (a) room temperature synthesis, (b) hydrothermal synthesis, (c) microwave assisted synthesis, and (d) a biphasic reaction) as revealed by SEM and TEM studies. While in most cases the metal phosphonates were isolated as insoluble crystalline powders directly from the reaction mixture, the use of 3,5‐dimethylpyrazole (DMP) as co‐ligand leads to the isolation of soluble compound [{Co(H2O)4(DMP)2}{CyPO3H}2]n (2) as single crystals. The X‐ray diffraction studies on 2 reveal a hydrogen‐bonded polymeric structure for this compound. Crystal data: C22H48CoN4O10P2, monoclinic, P21/c, a = 12.147(2), b = 11.607(2), c = 11.872(2) Å, β = 104.00(3)°, V = 1624.2(5) Å3, Z = 2, R1(all data) = 0.050, wR2 (all data) = 0.145.
Experimental and Theoretical Approaches to the Protonation of Thiourea: A Convenient Nucleophile in Coordination Chemistry Revisited
Authors: Schiessl Wolfgang C. , Summa Nadine K. , Weber Christian F. , Gubo Sonja , Dücker‐Benfer Carlos , Puchta Ralph , van Eikema Hommes Nico J. R. , van Eldik Rudi 
Published: October 2005

AbstractThe protonation of thiourea was reinvestigated in aqueous and non‐aqueous media using potentiometric, UV‐vis, NMR, MS spectroscopy, as well as DFT calculations. In aqueous medium, no evidence for protonation could be found in the pH range 0 to 7, in agreement with typical pKa values (acid dissociation constants of protonated thiourea) quoted in the literature of around ‐1.2. Most of the protonation constants quoted in the literature are incorrect and apparently refer to pKa values. Protonation of thiourea occurs at a much higher pKa value in methanol and in water‐dioxane mixtures, which must be related to the stabilization of the protonated species in such media.
In vitro Synthesis and Structural Characterization of Amorphous Calcium Carbonate
Authors: Günther C. , Becker A. , Wolf G. , Epple M. 
Published: October 2005

AbstractAmorphous calcium carbonate (ACC) was prepared in vitro by different methods. The preparation from carbon dioxide and aqueous calcium hydroxide gave a fully X‐ray amorphous phase without any additive. The precipitation from calcium chloride and sodium carbonate in the presence of either magnesium or ethylene‐diamine‐N,N,N′,N′‐tetrakis‐methylene‐phosphonic acid (EDTMP) also gave fully amorphous solids. All ACC phases contained about 7 wt% of residual water and transformed into crystalline phases upon contact with gaseous or liquid water. These materials are model compounds for biogenic ACC which is of importance in biomineralisation either as functional material or as a transient phase on the way to calcite or aragonite. If ACC is prepared in vitro without any additive, a clear short‐range order around calcium can be determined by X‐ray absorption spectroscopy (EXAFS). Additive‐free ACC converts exclusively to crystalline calcite upon heating or in contact with water and may therefore act as a model compound for biologically found transient precursor phases.
Influence of the Steric Demand of the 2,4,6‐Trialkylphenyl Substituents on the Structures and Reactivity of Diarylzinc
Authors: Westerhausen Matthias , Oßberger Manfred W. , Alexander Jacob S. , Ruhlandt‐Senge Karin 
Published: October 2005

AbstractThe Grignard reaction of 2,4,6‐tri(tert‐butyl)phenylmagnesium bromide with zinc dichloride in THF yields monomeric bis[2,4,6‐tri(tert‐butyl)phenyl]zinc (1). Due to the steric demand of the tert‐butyl groups 1 has a bent CZnC moiety and the boat‐shaped aryl groups are in a staggered conformation. After the transmetallation of 1 with cesium in a solvent mixture of 1,2‐dimethoxyethane (DME) and toluene (1,2‐dimethoxyethane‐O,O′)cesium [2,4,6‐tri(tert‐butyl)phenolate] (2) is isolated. A polymeric structure is formed in the crystalline state by linkage of these molecules via a Cs‐O bond of the phenolate oxygen atoms and a η6‐coordination of the aryl moiety of another molecule to the cesium cations. Furthermore, in the solid state the cesium cation completes his coordination sphere by bonds to a bidentate ether molecule and by close contacts to a tert‐butyl group of a neighboring molecule.
5‐Chloro‐5‐trifluoromethyl‐3‐aryl‐4‐alkyl(aryl)‐isothiazolidines and their Dehydrochlorination Reactions
Authors: Solov'ev Alexander V. , Chernega Alexander N. , van Almsick Andreas , Hoffmann Michael G. , Shermolovich Yuriy G. 
Published: October 2005

AbstractN‐Alkyl(aryl)‐C‐trifluoromethyl‐C‐chlorosulfinimides and styrenes react to give the 3+2 cycloaddition products, 5‐chloro‐5‐trifluoromethyl‐3‐aryl‐4‐alkyl(aryl)‐isothiazolidines 9a‐h. The structure of the dehydrochlorination products derived from the compounds 9a‐h is determined by the nature of the substituent near the nitrogen atom. The compounds having bulky tertiary‐butyl group (9c,h) are transformed into the isothiazolines derivatives 10a,b, but compounds 9a,b,d‐g form β‐aminovinyl trifluoromethylthioketones 11a‐f.
Producing Hazardous Reagents In Situ Using Single‐Site Heterogeneous Catalysts
Authors: Raja Robert , Meurig Thomas John 
Published: October 2005

AbstractThe in situ production and containment of aggressive and hazardous reagents (as well as the avoidance of the use of ecologically harmful ones) has been much assisted by the design of appropriate open‐structure single‐site heterogeneous catalysts, such as those consisting of metal‐ion‐framework‐substituted aluminophosphates, MAlPOs. A range of nanoporous solids, that meet most of the stringent demands of sustainable development and responsible (clean) technology is described. Specific examples that are highlighted include: (a) the in situ production of peracetic acid from a solid oxidant, acetylperoxyborate (APB), employing MnAlPO‐5 or FeAlPO‐5 as the catalysts, for the catalytic oxidation of styrene to styrene oxide, and for the oxidation reactions of α‐pinene and (+)‐limonene to produce the corresponding epoxides in high yields and high selectivities; (b) the in situ generation of peracids using a sacrificial aldehyde and air for the catalytic epoxidation of alkenes and Baeyer‐Villiger oxidations of cyclic ketones to lactones using MnIII (or CoIII)‐framework‐substituted MAlPO‐catalysts and (c) the in situ catalytic generation of hydroxylamine using a mixture of air and ammonia for the production of oximes and ϵ‐caprolactam employing carefully designed bifunctional nanoporous catalysts.
Lanthanide Nitrate Complexes of the Unsymmetrical Bidentate Ligand Ph2PCH2CH2P(O)PPh2
Authors: Amenta Donna S. , Sparks S. Nikki , Gilje John W. , Edelmann Frank T. , Fischer Axel , Blaurock Steffen 
Published: October 2005

AbstractThe reaction of Ln(NO3)3 (Ln = Ce, Tb, or Yb) with Ph2PCH2CH2P(O)Ph2 in various molar ratios produces Ln(NO3)3(OPPh2CH2CH2PPh2)3. X‐ray powder diffraction demonstrates that the three compounds are isostructural. Single crystal X‐ray diffraction structures were obtained for Ln = Ce and Tb. The compound are isomorphous and crystallize in the trigonal R3c space group. The lanthanide ions are nine‐coordinate with three bidentate nitrate ions and three (OPPh2CH2CH2PPh2) ligands coordinated through oxygen. If the coordination sphere is defined by the three lanthanide‐nitrogen vectors and the three lanthanide‐O(P) bonds, the complexes can be described as facial octahedral. The chemistry of the Ph2P‐CH2CH2‐P(O)Ph2 ‐ Ln(NO3)3 system appears to be simpler than ones involving simple phosphine oxide ligands.
[1]Borametallocenophanes as Catalysts for Ethene Polymerization
Authors: Braunschweig Holger , Kraft Mario , Radacki Krzysztof , Stellwag Sascha 
Published: October 2005

AbstractIn the present paper we report the Ziegler‐Natta ethene polymerization behavior of a series of [1]borazirconocenophanes in comparison with industrially employed catalysts. The influence of the substitution pattern on steric and electronic parameters was estimated by X‐ray diffraction analyses and by 91Zr NMR spectroscopy, respectively. Incorporation of a boranediyl‐moiety increases the catalytic activity by up to 3.25 times compared to the parent, non‐bridged zirconocenedichloride. The stability of the species after activation was studied, by aging and by interrupting the polymerization for several hours. [1]Borazirconocenophanes proved to form a stable species after activation with MAO, which is even after 20 h still highly active.
Synthesis and Characterization of New Mono‐, Di‐, and Trinuclear Copper(II) Triethanolamine‐Carboxylate Complexes
Authors: Escovar Raphael M. , Thurston John H. , Ould‐Ely Teyeb , Kumar Arvind , Whitmire Kenton H. 
Published: October 2005

AbstractA series of triethanolamine copper(II) carboxylate complexes have been synthesized and characterized both structurally and spectroscopically. The structures of the compounds and the nuclearity of the resulting coordination complexes are influenced both by the stoichiometry of the reagents and the steric and electronic influences of the anionic ligands present in the copper coordination spheres. The complexes can be prepared in high yields and purity as highly crystalline solids. Herein we report the spectroscopic and structural data for [NaCu(CF3COO)3(TEAH3)] (1), [Cu(C6H5COO)(TEAH2)]2·2H2O (2), [Cu3(CH3COO)4(TEAH2)2] (3), [Cu3(HCOO)4(TEAH2)2] (4) and [Cu3(CF3OO)2(TEAH2)2(CH3OH)2][CF3CO2]2 (5) (TEAH3 = triethanolamine (N(CH2CH2OH)3); [TEAH2]‐ = mono‐deprotonated ion; [TEAH]2‐ = doubly deprotonated ion). Two approaches to these compounds were employed: direct reaction of copper(II) carboxylates with TEAH3 and reaction of the tetrameric compound [{Cu(TEAH)}4] (6) with copper(II) carboxylates. Compound 1 is polymeric in the solid state, being a double salt of sodium trifluoroacetate and (triethanolamine)copper(II) trifluoroacetate, while 2 exists as a simple dimer. Compounds 3, 4 and 5 are trinuclear complexes with Cu3 chains connected by bridging carboxylate and triethanolamine ligands. 3 was characterized as three crystal modifications: an unsolvated form and as a methanol solvate 3·2MeOH that was found to exist in both monoclinic and orthorhombic forms. 4 was also found to exist as a methanol solvate, 4·1.70 MeOH. 5 shows coordination isomerism compared to compounds 3 and 4 in that two of the carboxylate ligands in the metal coordination spheres on the end copper atoms have been replaced by solvent methanol. The magnetic behavior of the di‐ and trinuclear species has been probed and reveals that at low temperatures the metal centers exhibit strong ferromagnetic coupling, which, on warming, switches to simple paramagnetic behavior.
Synthesis and Structural Characterization of 1,4‐Diazadiene Imido Tungsten Complexes
Authors: Merkoulov Alexei , Harms Klaus , Sundermeyer Jörg 
Published: October 2005

AbstractThe reaction of [W(NR)Cl4(L)] (R = Ph, Cy; L = thf) and Li2DAD (DAD = 1,4‐di‐tert‐butyl‐1,4‐diazabuta‐1,3‐diene) leads to the formation of [(DAD)W(NR)Cl2], R = Ph (1), R = Cy (2). Both complexes are examples of a growing class of complexes displaying an uncommon combination of two highly charged sterically demanding 6‐electron donors, NR2‐ and DAD2‐, at one coordination site. Surprisingly both complexes show weak Lewis acidity and don't react with σ‐donors such as PMe3 and THF. The crystal structure determination of 1 reveals a mononuclear molecular structure with folded DAD2‐ moiety. In accord with spectroscopic data and the W‐N, C‐N and C‐C bond lengths of the DAD ligand, the obtained compounds should be described as WVI imido ene‐diamido species.