bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unusual Ring‐Closure Reactions During the Oxidation of 1,1′‐Bi(3‐methylphosphol‐2‐ene) with Hexafluoroacetone — Formation of a Tricyclic Fluorine‐Containing Phosphorane
Authors: Vollbrecht Sebastian , Vollbrecht Alexander , Jeske Jörg , Jones Peter G. , Schmutzler Reinhard , Du Mont Wolf‐Walther 
Published: July 2007

AbstractReduction of the isoprene—PCl3 adduct 1 with magnesium powder, or with Si2Cl6, furnished P‐chloro‐3‐methyl‐phosphol‐2‐ene, 2, in satisfactory yield. Further reduction of 2 with Si2Cl6 gave the new trichlorosilyl‐3‐methylphosphol‐2‐ene, 3. The reaction of 2 with magnesium powder, with 3, or with 1/2 equivalent of Si2Cl6 provided the new γ3P‐γP‐diphosphane 1,1′‐bi(3‐methylphosphol‐2‐ene) 4. Reduction of 4 with Si2Cl6 led to 3. Oxidation of 4 with selenium gave the 1,2‐diphosphane diselenide, 5. The oxidation of 4 with hexafluoroacetone led to a mixture of products, from which a novel tricyclic phosphorane 6 was separated. the structure of 196 was determined by X‐ray diffraction; the coordination geometry at phosphorus in distorted trigonal bipyramidal, with a very long equatorial P—C(CF3)2 bond of 193.2(2) pm.
Organophosphorus Compounds, 119. The Phosphaalkyne Cyclotetramer System — Syntheses, Valence Isomerizations, and Reactions
Authors: Mack Andreas , Regitz Manfred 
Published: July 2007

AbstractIn contrast to their all‐carbon analogues, phosphaalkyne cyclooligomers only became accessible a few years ago. A milestone in the chemistry of cyclotetramers was the synthesis and structural characterization of the tetraphosphacubane 5, obtained as a thermolysis product of tert‐butylphosphaacetylene (1). Since then, the construction of eleven cyclotetramers has been achieved, covering seven different frameworks (A‐G). As a consequence of the use of kinetically stabilized phosphaalkynes as starting materials, all known cyclotetramers bear sterically demanding substituents (tert‐butyl, tert‐pentyl, 1‐adamantyl). Cyclotetramerizations are not only achieved by thermolysis of 1, but also by alternative and selective routes such as transition‐metal‐mediated, Lewis acid‐ and base‐induced processes, as well as by cycloadditions to phosphaalkyne cyclotrimers. Interestingly, these tetramers can be interconverted by various valence isomerizations. The results of thermal and photochemically‐induced rearrangements are in good agreement with MO calculations carried out for the parent compounds. Phosphaalkyne cyclotetramers exhibit a highly interesting reactivity and other peculiar features. One outstanding example is the tetraphosphacubane 5, which shows unusual structural and spectroscopic properties as a result of its unique bonding arrangement.
Organoamido‐ and Aryloxo‐Lanthanoids, 17 Novel Low‐Coordinate Lanthanoid (II) and ‐(III) Aryloxide Complexes ‐ the X‐ray Structures of Bis (2,6‐diphenylphenolato) tris(tetrahydrofuran)‐ytterbium (II), Bis(1,2‐dimethoxyethane)bis(2,6‐diphenylphenolato)ytterbium(II),‐neodymium(III)
Authors: Deacon Glen B. , Feng Tiecheng , Junk Peter C. , Skelton Brain W. , White Allan H. 
Published: July 2007

AbstractReduction of [Yb(Odpp)3(THF)2(HOdpp = 2,6‐diphenylphenol; THF = tetrahydrofuran) with ytterbium powder and mercury metal yields [Yb(Odpp)2(THF)3] (1) which on crystallization from DME gives [Yb(Odpp)2(DME)2] (2) (DME = 1,2‐dimethoxyethane). Crystallization of the reactant [Yb(Odpp)3(THF)2] from DME yields [Yb(Odpp)3(DME)]. (DME)0,5 (3) and of [Nd(Odpp)3(THF)2] from DME/THF the analogous [Nd(Odpp)3(DME)]. (THF) (4). The X‐ray crystal structure of 1 reveals distorted trigonal bipyramidal five‐coordinate ytterbium with axial Odpp ligands [O‐Yb‐O 164.6(3)˚], and unsymmetrically distributed equatorial THF ligands [O‐Yb‐O 137.5(3), 138.8(3), 83.7(4)°] owing to two close H(Ph)...Yb approaches (3.1‐3.2 Å). In 2, there is trigonal prismatic six‐coordination with an Odpp ligand on each triangular face and DME ligands bridging the triangular faces. Both 3 and 4 have distorted square planar five‐coordination for the lanthanoid metals with an apical Odpp ligand and cisoid Odpp ligands and a chelating DME in the square plane.
Cp3Zr(acetonitrile)+: Structure of an Electron‐Rich Organometallic d0‐Cation
Authors: Brackemeyer Thomas , Erker Gerhard , Fröhlich Roland , Prigge Jörg , Peuchert Ulrich 
Published: July 2007

AbstractThe organometallic salt [Cp3Zr(N≡C‐CH3)]+[CH3B‐(C6F5)3]−(3a) has been prepared by treatment of Cp3ZrCH3with B(C6F5)3followed by the addition of acetonitrile. X‐ray crystal structure analysis of3ashows that its cation consists of three uniformly coordinated η5‐cyclopentadienyl ligands about the zirconium atom. The acetonitrile ligand is end‐on coordinated. In the linear [Zr] ‐N≡C‐CH3unit the C≡N triple bond [N‐C2 1.126(5) Å] is slightly shorter than in the free acetonitrile molecule [dC≡N= 1.141(2) Å], the structure of which was determined as a reference by X‐ray diffraction of a crystal obtained by IR‐laser‐induced zone melting on the diffractometer.
Contribution to the Chemistry of Boron, 238 Synthesis and Assembly Mechanism for Spirocyclic Cage Compounds Containing, B, P and Si Atoms
Authors: Chen Tuqiang , Duesler Eileen N. , Paine Robert T. , Nöth Heinrich 
Published: July 2007

AbstractReactions of 1‐lithio · DME‐2,4‐bis(dialkylamino)‐l,3,2,4‐diphosphadiboretanes (1a, 1b) with SiCl4 followed by dehydrohalogenation with tBuLi produce spirocyclic compounds [(R2NB)2P2]2Si (2a, 2b). The compounds have been characterized by spectroscopic methods and X‐ray crystallography. The assembly process has also been followed and one intermediate species [(iPr2NB)2P2][(iPr2NB)P(H)(iPr2NB)P]SiCl (3) has been isolated and fully characterized.
(η6‐Arene)ruthenium(II) Labeling of Amino Acids and Peptides with Aromatic Side‐Chains
Authors: Wolff Jens M. , Sheldrick William S. 
Published: July 2007

AbstractBis(arene)ruthenium(II) complexes of the type [(η6‐cymene)Ru(η6‐aa)](CF3SO3)n (2‐9) containing L‐tyrosine and L‐tryptophan derivatives may be prepared by treatment of [(η6‐cymene)Ru({CH3)2CO}3](CF3SO3)2 with the appropriate bioligand in CH2Cl2, for fully protected compounds and CF3COOH for α‐amino acids (aa) with unprotected amine or carboxylic acid groups. Whereas the tyrosine and tryptophan methyl ester complexes [(η6‐cymene)Ru(η6‐H2tyrOMe)](CF3SO3)3 (4) and [(η6‐cymene)Ru(η6‐H2trpOMe)](CF3‐SO3)3 (8) contain trications with protonated amino functions, the remaining compounds all exhibit dications. The crystal structure analysis of [(η6‐cymene)Ru(η6‐HtyrOH)](CF3SO3)2 (5) confirms a marked distortion towards an η5‐oxohexadienyl coordination with deprotonation of the aromatic side chain. Although facial isomers are formed in an effectively 1:1 ratio for all tryptophan derivatives fractional crystallization allowed an X‐ray structural characterization of the β‐isomer of [(η6‐cymene)Ru(η6‐ActrpOMe)](CF3SO3)2 (6). Chemospecific labeling of the tryptophan side chain was established for the mixed dipeptide phenylalanyltryptophan.
Enantioselective Catalysis, XV Preparative and Structural Chemistry of Diastereomeric Derivatives of 3‐Phosphanylpyrrolidine and Their Palladium(II) Complexes ‐ Asymmetric Grignard Cross‐Coupling Reaction
Authors: Nagel Ulrich , Nedden Hans Günter 
Published: July 2007

AbstractThe preparation of both diastereomeric derivatives of 3‐(diphenylphosphanyl) pyrrolidine with chiral (tetrahydrofuran‐2‐yl)methyl and [(N‐neopentyl)pyrrolidin‐2‐yl]methyl groups as substituents on the pyrrolidine nitrogen atom and of (2S,4S)‐1‐benzyl‐4‐(diphenylphosphanyl)‐2‐(methoxymethyl) pyrrolidine is reported. [3S,P(RS)]‐3‐(phenylphosphanyl) pyrrolidine, bearing an additional chiral center on phosphorus, is the starting material for the preparation of phosphanes, in which one phenyl group of the PPh2moiety is substituted by an 2‐methoxyphenyl (=An) or 2,4,6‐trimethoxyphenyl (=TMP) group. PdI2complexes of these ligands were separated into diastereomers by chromatography on silica gel columns. The structural chemistry of these novel phosphane diastereomers and their PdI2complexes is investigated by X‐ray crystallography and NMR. At theP,N‐coordinated palladium center displacement of an iodide anion is found for P,N,N′ ligands only. In the nickel complex catalysed cross‐coupling reaction, yielding 3‐phenyl‐1‐butene, we obtain the highest enantioselectivities in the case of simple 1‐alkyl‐3‐(diphenylphosphanyl)pyrrolidine ligands. The enantioselectivity obtained with diastereomeric derivatives, bearing additional ether or amine ligating sites is mainly determined by the chiral center in 3‐position of the 3‐(phosphanyl) pyrrolidine part of these ligands. Optimisation of enantioselectivity with these ligands can be carried out by a variation of the ligand to nickel ratio and by the choice of the vinyl halide used as starting compound. The catalytic cycle must contain at least one catalytically active species, bearing more than one β aminoalkylphosphane ligand.
Pseudoelement Compounds, X Synthesis and Crystal Structure of New Complexes of the Type trans‐[Pt(H)X(PPh3)2 with Cyanamide and Cyanomethanide Ligands
Authors: Jäger Lothar , Tretner Carola , Hartung Helmut , Biedermann Mathias 
Published: July 2007

AbstractThe new coordination compounds trans‐[Pt(H)X(PPh3)2] with NCN‐ and C(CN)2‐functionalized anions (X− = [N(O)C(CN)2]−, [NO2NCN]−, [N{C(CN)2}2]−, [NCC{C‐(CN)2}2]−, have been characterized by 1H‐, 31P‐, 13C‐NMR, and IR spectroscopy and elemental analyses the crystal structures of trans‐[Pt(H)N(O)C(CN)2(PPh3)2], trans‐ [Pt(H)N{C(CN)2}2(PPh3)2], and trans‐[Pt(H)NCC{C(CN)2}2‐(PPh3)2) have been determined by X‐ray diffraction. Remarkably, [N(O)C(CN)2]− is coordinated through the central nitrogen atom, while [N{C(CN)2}2]− and [NCC(C(CN)2]2]− are bonded through terminal nitrogen atoms of a C(CN)2 unit.
The Reactivity of Complexes of Nickel(0) and Platinum(0) Containing Benzyne and Related Small‐Ring Alkynes
Authors: Bennett Martin A. , Wenger Eric 
Published: July 2007

AbstractThe preparation and reactivities of cyclohexyne and aryne complexes of platinum(0) and nickel(0) are reviewed. These complexes undergo insertions with unsaturated molecules such as alkenes, alkynes, isocyanides, CO and CO2. In the case of the nickel‐ benzyne complexes, consecutive insertions are observed with alkynes, leading to substituted naphthalenes with good regioselectivities. A possible mechanism for these double insertions, based on a combination of steric and electronic factors, is discussed in detail.
Thio‐Ligation to Vanadium: The NSSN and S′N′O Donor Sets (N = Pyridine, N′ = Enamine; S = Thioether, S′ = Thiolate)
Authors: Farahbakhsh Mahin , Nekola Henning , Schmidt Häke , Rehder Dieter 
Published: July 2007

AbstractThe tetradentate, neutral disulfide [bis(thioether)] ligand 1,6‐bis(o‐pyridyl)‐2,4‐dithiahexane, NSSN, reacts with [VCI2(tmeda)2] to form the octahedral (all‐cis; C2v‐symmetric) complex [VCl2(NSSN)] 1, the first low‐valent vanadium complex in which the thio functions are exclusively organic sulfides. Treatment of (VOCl2(thf)2] with O‐mercaptoaniline, followed by reaction with o‐hydroxynaphthaldehyde yields the non‐oxo V′” complex [V(S′N′O)2] 2, derived from the Schiff base HS′N′OH, where 0 and S′ are phenolate and thiophenolate functions, respectively, and N′ is the Schiff base (enamine) nitrogen. Complex 2, with the ligands in a distorted trigonal‐antiprismatic array, is a rare example of a structurally characterized complex where the Schiff base is preserved at the expense of its thiazoline tautomeric form.
Ab Initio Studies on Disubstituted closo‐Icosahedral Heteroboranes, X2B10H10 [X = CH, SiH, N, P, and Sb]
Authors: Jemmis Eluvathingal D. , Kiran Boggavarapu , Coffey Dewitt 
Published: July 2007

AbstractAb initio theoretical studies on X2B10H10 (X = CH, SiH, N, P and Sb) have been done for all the three possible isomers. Unlike lower‐vertex heteroboranes, all the hetero derivatives have shown similar trends in the relative stabilities, the 1,12‐isomer being more stable followed by 1,7‐ and 1,2‐isomers, except for N and Sb. No conventional 1,2‐isomer for N could be found. Instead, a new nido isomer which is 18.1 kcal/mol higher in energy than the most stable isomer has been located. Any hetero group substitution to icosahedral R12H122− is found to be thermodynamically destabilizing. However, the Nucleus Independent Chemical Shift criterion shows that all compounds, except for 8, have similar aromaticity.
The Molecular Structures of Triaminosilanes
Authors: Huber Gerald , Mitzel Norbert W. , Schier Annette , Schmidbaur Hubert 
Published: July 2007

AbstractThe structural chemistry of a series of triaminosilanes XSi(NR2)3 has been investigated in order to determine the ground‐state configuration and conformation of these molecules. Theoretical studies and analogy with the isoelectronic XP(NR2)3 (X = CH2, O, Se, NSiMe3 etc.) and P(NR2)3 molecules suggest structures of Cs or C3 symmetry, with small energy differences between them. The molecular structure of HSi(NMe2)3 (1) has been determined by a single‐crystal X‐ray diffraction study at low temperature. Surprisingly, the molecules have a non‐standard conformation with an irregular orientation of the three NMe2 groups. The hydrido‐, chloro‐, methyl‐, and vinyltris(morpholino)silanes XSi[N(CH2CH2)2O]3 (X = H, Cl, Me, Vi; 2–5) were prepared from the corresponding chlorosilanes and morpholine (2, 3) or lithium morpholide (4,5). Their variable‐temperature NMR spectra were studied and the molecular structures determined by single crystal X‐ray diffraction. Compound 2 has a molecular geometry approaching mirror symmetry with one morpholino group significantly different from the other two. This structure resembles that of isoelectronic tris(amino)phosphines. Compounds 3–5 have structures with a propeller‐like arrangement of the three morpholino rings approaching C3 symmetry for this part of the molecules. The chloro compound 3 shows the shortest Si‐N bond lengths (average 1.690 Å), followed by 2 (1.708Å),5 (1.709Å) and 4 (l.712Å). The configuration of all nitrogen atoms is almost planar, with sums of the angles close to 360°, and the morpholino rings adopt a chair conformation. According to the solution NMR spectra the ring inversion is slow at low temperature, but the rings rotate freely about the Si‐N bonds on the NMR time scale. The molecular structures are discussed in terms of steric and electronic effects of the substituents. Other model compounds, including (Me2N)3SiC6H4‐4‐Br (6), MeSi[N(CH2CH2)2NMe]3 (7) and PhSi[N(CH2)4]3 (8), could not be crystallized, but were characterized by their analytical and spectroscopic data.
Organometallic Chemistry sans Organometallic Reagents: Modulated Electron‐Transfer Reactions of Subvalent Early Transition Metal Salts
Authors: Eisch John J. , Shi Xian , Alila Joseph R. , Thiele Sven 
Published: July 2007

AbstractThe potential of low‐valent, early transition‐metal reagents as selective reductants in organic chemistry has been foreshadowed by intensive research on the ill‐defined and heterogeneous subvalent titanium intermediates generated in the McMurry reaction and its numerous variants. As part of the long‐term research effort to develop soluble, well‐defined transition‐metal reductants of modulated and selective activity toward organic substrates, the THF‐soluble reductant, titanium dichloride, has been throughly examined, as well as the analogous ZrCl2 and HfCl2 reagents, all of which are readily obtainable by the alkylative reduction of the Group tetrachloride by butyllithium in THF. Noteworthy is that such interactions of MCl4 with butyllithium in hydrocarbon media lead, in contrast, to M(III) or M(IV) halide hydrides. Analogous alkylative reductions in THF applied to VCl4, CrCl3, and MoCl5 have yielded reducing agents similar to those obtained from Mcl4 but gradated in their reactivity. Such reductants have proved capable of coupling carbonyl derivatives, benzylic halides, acetylenes and certain olefins in a manner consistent with an oxidative addition involving a two‐electron transfer (TET). Such a reaction pathway is consistent with the observed stereochemistry of pinacol formation from ketones and for the reductive dimerization of alkynes. In contrast of the reaction of CrCl3 with two equivalents of butyllithium, which leads to a CrCl intermediate, the interaction of CrCl3 in THF with four equivalents of butyllithium at –78°C yields a reagent of the empirical formulation, LiCrH4.2LiCl.2 THF, as supported by elemental and gasometric analysis of its protolysis. This hydridic reductant cleaves a wide gamut of s̀ carbon–heteroatom bonds (C–X, C–O, C–S and C–N), towards which the CrCl reductant is unreactive. The type of cleavage and/or coupled products resulting from the action of “LiCrH4” on these substrates in best understood as arising from single‐electron transfer (SET). In light of the aforementioned findings, the gradated reducing action noted among TiCl2, HfCl2 and CrCl, as well as the contrasting reducing behavior between CrCl and LiCrH4, there is no doubt that future research with early transition metals will continue to yield novel reductants of modulated and site‐selective reactivity.
Photochemical Reactions of a Binuclear Naphthalene‐Manganese Complex with 2‐Butyne
Authors: Kreiter Cornelius G. , Georg Andreas , Reiß Guido J. 
Published: July 2007

AbstractPentacarbonyl(μ‐.4:6‐1,4‐dimethylnapthalene)dimanganese‐(Mn–Mn) (1), upon UV irradiation at 193 K in the presence of 2‐butyne (2), yields tetracarbonyl(μ‐.2:2‐2‐butyne)(μ−1,2,3,4‐.:1,4,4a,8a‐.‐1,4‐dimethylnaphthalene)dimanganese (3) and tricarbonyl(4a,6,7,8,8a‐.−5‐hydro‐1,4‐dimethylnapthalene)‐manganese (4). The tetracarbonyl complex 3 rearranges in solution at room temperature to give tetracarbonyl(μ‐.2:2‐2‐butyne)(μ−4a,5,8,8a‐.:5,6,7,8‐.−1,4‐dimethylnaphthalene)‐dimanganese (5). The complexes 3 and 5 were characterised by IR and NMR spectroscopy, and by mass spectrometry, and complex 4 by IR and NMR spectroscopy. The molecular structures of 3 and 4 were determined by single‐crystal X‐ray diffraction analyses.
Carbene Structure of Stable Acyl (Formyl) Anion Equivalents
Authors: Hill Christof , Bosold Ferdinand , Harms Klaus , Lohrenz John C. W. , Marsch Michael , Schmieczek Michael , Boche Gernot 
Published: July 2007

Abstract3‐Lithiated 4‐tert‐butyl‐imidazol‐2‐ylidene, 3‐lithiated 4‐tert‐butyl‐thiazol‐2‐ylidene, and the ZnBr species of the latter, are shown to be stable carbenes by X‐ray crystal structure determination. The crystal data are confirmed by 13C‐NMR investigations in solution and quantum‐chemical calculations. The exceptional stability of the acyl anion equivalents is due to the p(.) stabilization of the carbene carbon atoms by the adjacent amino (thio) substituents, as is also the case in the structurally related stable carbenes, which have recently been isolated for the first time by A. J.Arduengo III et al., and in stable nitrenium ions, as found by our group.
The First Monofluorenyl Zirconium Trichloride
Authors: Van Der Zeijden Adolphus A. H. , Mattheis Chris , Fröhlich Roland 
Published: July 2007

AbstractThe monofluorenyl zirconium complex [(.(5):.1‐C13H8CH2CH2OMe)ZrCl2(μ‐Cl)]2, (2), has been obtained bby reaction of the respective fluorenyl lithium derivative with ZrCl4 in diethyl ether. A single‐crystal X‐ray structural analysis shows that 2 is a chloride‐bridged dimer, in which the fluorenyl ligand is bonded in a transitional tri‐ to pentahapto fashion. The relatively weak fluorenyl–zirconium bond is stabilized by intramolecular coordination of the ether sidechain attached to the fluorenyl backbone. Despite this, the bidentate ligand is easily detached upon dissolution of 2 in THF. Simultaneous ether cleavage produces spiro[cyclopropane‐1,9′‐fluorene].
Benzil Derivatives as Trapping Reagents for the Monomeric Alkylindium(i) Compound in–c(SiMe3)3
Authors: Uhl Werner , Keimling Sven Ume , Phol Siegfried , Saak Wolfgang , Wartchow Rudolf 
Published: July 2007

AbstractThe tetrahedral cluster compound tetrakis[[Tris(trimethylsilyl)methyl]indium(I)] 91) reacts in boiling n‐hexane with benzil derivatives (p‐X‐C6H4)C(O)(p‐X‐C6H4) (X = H, OMe, Br), to yield the 1,4‐cycloadditon products of the monomeric alkylindium(I), In–C(SiMe3)3, in which the In atoms are coordinated by a chelating enediolato ligand, to form a five‐membered InO2C2 heterocycle. As shown by two crystal structure determinations (X = H, OMe), the products are dimeric in the solid state, with a four‐membered In2O2 heterocycle in the molecular center and both C(SiMe3)3 groups, as well as both enediolato substitutents in a cis arrangement.
Cyclocarbonylation of Bicyclic Vinylcyclopropanes – Selective Generation of Seven‐Membered Enones
Authors: Schulze Matthias M. , Gockel Ulrich 
Published: July 2007

AbstractThe cyclic vinylcyclopropane 6a reacts at elevated temperatures with iron pentacarbonyl to selectively give the enone 7a in 52% yield. Reducing the reaction time provided the isomeric ketones 7a–b. Partial chromatographic separation of this mixture allowed the complete spectroscopic identification of 7b by 1H NMR. The structure of 7c was determined from selected spectral data of the mixture of 7a and 7c. For comparison, the methyl substituted derivate 6b was subjected to a carbonylation under the above conditions exclusively providing 8 ini 42% yield. A mechanistic rationale for the two different modes of ring opening is presented.
Regioselective Complexation of New Multiple Piperazine/Pyridine Ligands: Differentiation by 113Cd‐NMR Spectroscopy
Authors: Ratilainen Jari , Airola Karri , Kolehmainen Erkki , Rissanen Kari 
Published: July 2007

AbstractEleven novel piperazine containing open‐chain ligands L1–L11 were designed to offer symmetrical and asymmetrical complexation sites for metal ions and were synthesized by repetitive synthetic method. The divergent use of aromatic bishalomethyl and mono‐N‐alkylated piperazine compounds as spaces led toa series of long (up to M. W. = 836) oligomeric multidentate N‐ligands. Due to the lack of solid state methods for structure analysis, an NMR technique using 113 Cd nucleus as a probe in solution state was utilised. 113 Cd chemical shifts were observed to be dependend on the coordination site and similar coordination sites in different ligands gave characteristically similar 113 Cd chemical shifts. As a result 113 Cd‐NMR spectroscopy proved to be an excellent tool to distinguish between the structures of the different complexation sites on a nearly quantitative level.
Ambient‐Pressure Organic Superconductors κ‐(DMEDO‐TSeF)2[Au(CN)4](solv.): Tc Tuning by Modification of the Solvent of Crystallization
Authors: Shirahata Takashi , Kibune Megumi , Yoshino Hiroko , Imakubo Tatsuro 
Published: July 2007

AbstractThe unsymmetrical π donor dimethyl(ethylenedioxy)tetraselenafulvalene (DMEDO‐TSeF) has provided six new organic superconductors with a monovalent square‐planar [Au(CN)4]− ion and cyclic ethers as solvent of crystallization. The six new organic superconductors κ‐(DMEDO‐TSeF)2[Au(CN)4](solv.) [solv.=1,3‐dioxolane (DOL), 2,5‐dihydrofuran (DHF), tetrahydropyran (THP), 1,3‐dioxane (1,3‐DOX), 3,4‐dihydro‐2H‐pyran (DHP), or 1,4‐dioxane (1,4‐DOX)] are classified into two subphases κL and κ′ according to the differences in their space group symmetry. κL‐(DMEDO‐TSeF)2[Au(CN)4](solv.) (solv.=DOL, DHF, THP, 1,3‐DOX or DHP) crystallizes in the orthorhombic space group Pnma, and Tc of the κL phase varies by 1.7–5.3 K according to the size and shape of the solvent of crystallization. On the other hand, κ′‐(DMEDO‐TSeF)2[Au(CN)4](solv.) (solv.=DOL or 1,4‐DOX) crystallizes in the noncentrosymmetric monoclinic space group Cc. The κ′‐phase containing 1,4‐DOX shows superconductivity at 4.2 K, but the κ′‐phase containing DOL does not show superconductivity down to 1.4 K. Systematic investigation of the six new organic superconductors, together with the two previously reported superconductors κH‐ and κL‐(DMEDO‐TSeF)2[Au(CN)4](THF), revealed that the Tc of the present system is finely tunable by utilizing the effect of the solvent of crystallization.