bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural Chemistry of Lithium Hydrazides
Authors: Nöth Heinrich , Sachdev Hermann , Schmidt Martin , Schwenk Holger
Published: July 2007

Deprotonation of NH protons, of four diorgano‐, organo(trimethylsilyl)‐ and bis(trimethylsilyl)hydrazines by n‐butyllithium in hexane led to the following lithium hydrazides: [Et‐(Li)N‐N(H)Et]6, (1)6, [Me3Si(Li)N‐N(Li)SiMe3]4, (2)4, [Me3Si‐(Li)N‐N(Li)SiMe3 · (Me3Si)2N‐N(Li)SiMe3]2 (3)2, and [Ph‐(Li)N‐N(Li)SiMe3]4, (4)4, respectively. The structure determination by X‐ray methods at low temperature reveals butterfly‐shaped Li2N2 structural monomeric units which associate through “laddering” to the observed oligomers thereby generating penta‐ and hexacoordinated Li centers. N‐N bonds lengths of up to 1.556 Å suggest that negative charge accumulates at the nitrogen atoms of (1)6, (2)4, and (3)2. An amazing structure shows the red compound 4 where two Li ions are π‐sandwiched between two phenyl groups each. The compound can be looked at as a new type of a lithium lithiate complex, Li2[Li6N8Ph4(SiMe3)4], but short N‐C and N‐N bonds in the Li6N8 core indicate that its negative charge is transferred to the phenyl groups.
Synthese und Struktur zweikerniger Kupfer(II)‐Komplexe eines neuen Hexaaza‐Makrocyclus mit verbrückenden Oxalat‐ und Acetat‐Ionen
Authors: Warzeska Sabine , Krämer Roland
Published: July 2007

Synthesis and Structure of Dinuclear Copper(II) Complexes of a Novel Hexaaza Macrocycle Containing Bridging Oxalate and Acetate Ions

Non‐template Schiff base [2 + 2] condensation of pyridine‐2,6‐dicarbaldehyde with 1,4‐diamino‐2‐butyne yields the hexaazamacrocyclic ligand 1, which is converted to 2 by NaBH4 reduction of the imino groups. Two dinuclear copper(II) complexes of 2 containing oxalate and acetate ions, [(2)Cu2(μ‐C2O4)](BPh4)2 (3) and [(2)Cu2(μ‐CH3CO2)(OH2)](PF6)(NO3)0.75 (4), were characterized by X‐ray crystallography. The oxalate ligand in 3 forms a (μ‐η4:η4) bridge between the copper atoms. Compound 4 contains a syn‐anti‐bridging acetate ion. The Cu‐Cu distances are 5.315 Å in 3 and 4.746 Å in 4, respectively. Oxalate can be separated from other carboxylates in aqueous solution by selective binding to the [(2)Cu2] unit and precipitation of 3.
Synthesis, Structure and Reactivity of [(acac)AuCH(PPh2AuPPh2)2CHAu(acac)], a Complex Containing the Tridentate Ligand [HC(PPh2)2]−
Authors: Fernández Eduardo J. , Concepci Gimeno M. ÁN , Jones Peter G. , Laguna Antonio , Laguna Mariano , Lápez‐de‐Luzuriaga José M. , Rodríuez Miguel A.
Published: July 2007

The complex [(acac)AuCH(PPh2AuPPh2)2CHAu(acac)] (1) is obtained by various procedures: a) by reaction of [Ph3PAuCH (PPh2AuPPh2)2CHAuPPh3](ClO4) 2 with NBu4[Au(acac)Cl], b) by reaction of [ClAuCH(PPh2AuPPh2)2CHAuCl] with [Au(acac)PPh3] or with Tl(acac) and c) by reaction of [ClAuPPh2CH2PPh2AuCl] with Tl(acac). The acetylacetonato ligand can act as deprotonating agent; thus, complex 1 reacts with (phosphane)gold complexes, [Au(C6F5)2{(PPh2)2‐CH2)]ClO4, [Au(C6F5)3(PPh2CH2PPh2)] or [Au(PPh3)2]ClO4, to give the hexanuclear complexes [(C6F5)2Au{(PPh2)2CH} AuCH(PPh2AuPPh2)2CHAu{CH(PPh2)2) Au(C6F5)2](ClO4)2, [(C6F5)3Au(PPh2CHPPh2)AuCH (PPh2AuPPh2)2CHAu‐(PPh2CHPPh2)Au(C6F5)3] or [(Ph3PAu)2C(PPh2AuPPh2)2C‐(AuPPh3)2](ClO4)2, respectively. The crystal structure of 1 has been established by X‐ray crystallography and displays two independent eight‐membered rings with inversion symmetry and short transannular gold‐gold contacts. The first ab initio results for a transannular AuI‐AuI interaction are reported.
Stereospecific Ligand Substitutions in Manganese(I) Complexes
Authors: Tsai Shiou‐Chuan , Wang Hsin‐Ell , Huang Chi‐Tsuan , Yiin Lih‐Ming , Liu Shiuh‐Tzung
Published: July 2007

Treatment of fac‐[(P2SPh‐P,P')Mn(CO)3Br] and fac‐[(PS2Ph‐P,S)Mn(CO)3Br] [P2SPh: Z = PPh2; PS2Ph: Z = SPh in CH3C‐(CH2PPh2)(CH2SPh)(CH2Z)] with silver hexafluorophosphate yields the η3‐tripodal manganese complexes [(P2SPh‐P,P',S)Mn(CO)3]PF6 (7) and [(PS2Ph‐P,S,S')Mn(CO)3]PF6 (9), respectively, whereas the reaction of CH3C(CH2PPh2)2‐(CH2SH) with Mn(CO)5Br gives directly [CH3C(Ph2‐PCH2)2(CH2S)‐P,P',S]Mn(CO)3 (11). Both ionic complexes 7 and 9 undergo stereospecifically ligand substitution upon treatment with Br−, I−, N−3, SCN− and CN− to give syn‐fac‐[(P2SPh‐P,P')Mn(CO)3X] and syn‐fac‐[(PS2Ph‐P,S)Mn(CO)3X] (X = Br, I, SCN, N3, CN) respectively, but the neutral complex 11 fails to undergo such a substitution reaction with these ions. However, reaction of I− with the complex [(PSMe)‐P,P',S]Mn(CO)3]BF4 (20) [P2SMe = CH3C(CH2‐PPh2)2(CH2SCH3)), which is obtained from the S‐alkylation of 11 with (CH3)3OBF4, affords syn‐fac‐[(P2SMe)‐P,P']Mn(CO)3I (22s) exclusively. The possible reaction mechanism of this ligand substitution is discussed.
Oxacycloalkenyliden‐Komplexe von Chrom, Molybdän und Wolfram: Synthese, Anellierung mit Alkinen und Diels‐Alder‐Reaktionen mit Dienen
Authors: Christoffers Jens , Dötz Karl Heinz
Published: July 2007

Reactions of Complex Ligands, LXI[1]. ‐ Oxacycloalkenylidene Complexes of Chromium, Molybdenum, and Tungsten: Synthesis, Their Annulation with Alkynes and Diels‐Alder Reaction with Dienes

Lithiiated propargylic ether 1 reacts with M(CO)6 (M = Cr, Mo, W) to give the 2‐oxacyclic carbene complexes 2–4 containing an α,β‐double bond and a cyclic acetal structure which serves as a protected benzoyl group. Reaction of the chromium complex 2 with tolan leads to an acyl hydroquinone derivative 5. The tungsten complex 3 undergoes a [4 + 2] cycloaddition with cyclopentadiene to give two diastereomeric oxatricyclic carbene complexes 6 and 7 with an endo/exo selectivity of 3:1. The stereochemistry of the Diels‐Alder reaction is controlled by the configuration of the acetal carbon center.
Darstellung und Komplexierung von 1,4‐Dimethyl‐2,3‐bis(isopropyliden)‐1,4‐diboratetralin
Authors: Hauß Jan , Pritzkow Hans , Siebert Walter
Published: July 2007

Synthesis and Complexation of 1,4‐Dimethyl‐2,3‐bis(isopropylidene)‐1,4‐diboratetraline

1,4‐Dimethyl‐2,3‐bis(isopropylidene)‐1,4‐diboratetraline (2) is obtained from o‐dilithiumbenzene and 2,5‐dimethyl‐3,4‐bis(chloromethylboryl)‐2,4‐hexadiene in 61% yield. Its complexation with cyclopentadienylbis(ethene)cobalt leads to the triple‐decker bis(η5‐cyclopentadienylcobalt)‐μ‐η6,η6‐1,4‐dimethyl‐2‐isopropenyl‐3‐isopropyl‐1,4‐dihydro‐1,4‐dibora‐naphthaline (3) in low yield. However, the reaction of 2 with (C5H5)Rh(C2H4)2 and (C5Me5)Co(C2H4)2 originates complexes of a tricyclic ligand formed from 2 via conrotatoric [2 + 2] cycloaddition of the isopropylidene groups. (η5‐Cyclo‐pentadienylrhodium)‐η6‐tricyclo‐[6.4.0.03,6]‐2,4,4,5,5,7‐hexamethyl‐2,7‐diboradodeca‐1,3,9,11‐tetraene (4), (η5‐pentamethylcyclopentadienylcobalt)‐η6‐tricyclo‐[6.4.0.03,6]‐2,4,4,5,5,7‐hexamethyl‐2,7‐diboradodeca‐1,3,9,11‐tetraene (5) and its related dinuclear complex 6 could be isolated in 29, 10, and 31%, respectively. Their constitutions are derived from spectroscopic data and proven by X‐ray structure analysis of 4.
Darstellung und Struktur von Allyl(tripod)cobalt(I) und der Vergleich zum analogen Cobalt(II)‐Komplex
Authors: Sernau Volker , Huttner Gottfried , Scherer Johannes , Zsolnai Laszlo , Seitz Thomas
Published: July 2007

Preparation and Structure of Allyl(tripod)cobalt(I) and the Comparison with the Analogous Cobalt(I) Complex

The synthesis of the 18‐electron diamagnetic allyl(tripod)cobalt(I) complex [{CH3C(CH2PPh2)3}Co(η3‐C3H5)] (1) is presented. Its structure is established by the usual analytical techniques as well as by X‐ray analysis, and it is proved to be significantly different from that of the cationic 17‐electron species 1+.
Contributions to the Chemistry of Boron, 227. The P‐centered Chemistry of [(Di‐tert‐butylphosphanyl)imino]‐(2,2,6,6‐tetramethylpiperidino)borane
Authors: Kölle Peter , Nöth Heinrich , Stolpmann Holger , Thomann Martina
Published: July 2007

The elements oxygen, sulfur, and selenium add to the P atom of the title borane 1. In contrast to the formation of tmpBNP(X)tBu2 (X = S, Se), the P oxide (X = O) dimerizes to [tmpBNP(O)tBu2]2 (5) with an eight‐membered flat boat‐shaped B2N2P2O2 ring. Borane 1 reacts readily with Mel to yield a phosphonium salt 8 and with BBr3 to give an adduct 9 with a BP bond. In contrast, bis(dichloroboryl)‐methane not only adds to 1 to generate a coordinate BP bond but also chloroborates the BN triple bond, the final product being a new five‐membered heterocycle 10. Similarly, the BH3 component of BH3·SMe2 first adds to the P atom of 1 followed by reaction of a second mol of BH3·SMe2 which hydroborates the BN triple bond. Finally, metal carbonyl fragments add only to the P atom of 1, demonstrating also that the chemistry of the molecule 1 is dominated by the basicity of its P center.
Synthese und Charakterisierung stabiler Bis(phosphonio)isophosphindolylium‐Carbonylmetallate und eines kationischen Bis(phosphonio)isophosphindolylium‐Gold‐Komplexes
Authors: Gudat Dietrich , Nieger Martin , Schrott Martin
Published: July 2007

Synthesis and Characterisation of Stable Bis(phosphonio)isophosphindolyliumcarbonylmetallates and a Cationic Bis(phosphonio)isophosphindolylium‐Gold Complex

Herrn Professor Alfred Schmidpeter zum 65. Geburtstag gewidmet.

Reaction of 1,3‐bis(triphenylphosphonio)isophosphindolylium bromide, [L+][Br−] (1a), with Tl[Co(CO)4], Na[MoCp‐(CO)3], or Na[WCp(CO)3] (5a‐c) yields the corresponding ionic isophosphindolylium‐carbonylmetallates, 6a‐c. Whereas 1a fails to react with neutral metal carbonyls, a mixture of ionic complexes of the type [LAuX+][AuYZ−] (7a, X, Y, Z = Cl or Br) is formed by reaction with two equivalents of AuCl. Treatment of AuCl with the triflate [L+][OTf−] (1b), which is accessible from 1a via anion metathesis, furnishes [LAuCl+][OTf−] (7b). Both the carbonylmetallate 6c and the complex 7b have been characterized by X‐ray structure analyses. 7b displays enhanced reactivity as compared to 1b towards MeOH and H2O, forming the addition products 8 and 9a, b, the latter existing as two different diastereomers. Reactions of 7b with LiF, (Me2N)3PO, and (Et2N)2CNH), respectively, proceed via ligand exchange to yield equilibrium mixtures containing the cations [L+] and [LAuCl+].
Wasserlösliche Phosphane, IV. Tertiäre Alkylphosphane mit Ammoniumgruppen in den Seitenketten – Amphiphile mit basischen P‐Atomen
Authors: Bitterer Frank , Kucken Stefan , Stelzer Othmar
Published: July 2007

Water‐Soluble Phosphanes, IV. – Tertiary Alkylphosphanes with Ammonium Groups in the Side Chains — Amphiphiles with Basic P‐Atoms

By stepwise aminoalkylation of PH3 with Me2N(CH2)2Cl in the superbasic medium DMSO/KOH the secondary phosphane [Me2N(CH2)2]2PH (2) is obtained in good yields. Metallation of 2 with n‐BuLi and subsequent reaction with Me2N(CH2)2]2Cl affords the basic tertiary phosphane [Me2N(CH2)2]2]3P (3), which on protonation with Ph3P · HBr in CH2Cl2 gives {[HNMe2 − (CH2)2]3P}3+ 3 Br− (4a) with an extremely high solubility in water. By oxidation of 3 with H2O2 and N‐quaternisation with Me3O+ BF the cationic phosphane oxide {[Me3N(CH2)2]3PO}3+ 3 BF (5a) is formed, which could, however, not be reduced with SiHCl3 or Si2Cl6/NEt3 to the corresponding tricationic phosphane. Tertiary cationic phosphanes of type [RMe2N(CH2)2P(Oct)2]+ X− (8a, 8b, R = Me, C8H17; X = Br, I) are accessible by free radical addition of 1‐octene to 7b and 7d. Addition of formaldehyde to 7a gives the hydroxymethyl phosphane 10a. By methylation of [RMe2N(CH2)2PH2]+I− (7d and 7e, R = CnH2n+1, n = 8, 12) with Mel under controlled condition and subsequent deprotonation of the phosphonium salts 12b and 12c the cationic tertiary phosphanes 13a and 13b with long alkyl side chains may be obtained in good yields.
Preparation and Characterization of Biologically Active Bismuth(III) Tropolonato Complexes
Authors: Diemer Rolf , Keppler Bernhard K. , Dittes Uwe , Nuber Bernhard , Seifried Volker , Opferkuch Wolfgang
Published: July 2007

Two new types of bismuth(III) tropolonato complexes, nitratobis(tropolonato)bismuth(III) (1d) and phenylbis(tropolonato)bismuthin (1f), are synthesized and characterized by elemental analysis, 1H‐NMR, 13C‐NMR, IR spectroscopy, and conductivity measurements. The structures of 1d and aquabis(4,5‐benzotropolonato)bismuth(III) nitrate (6b) are confirmed by X‐ray structural analyses. Derivatives of tropolone (2a) and their bismuth(III) complexes are synthesized and characterized in the same manner. Eight of these compounds are tested against Helicobacter pylori (H.p.) bacteria, which cause chronic gastritis and peptic ulcus. Most of the bismuth compounds show high in vitro activity against H.p.
Perfluororganochalkogensäuren in hohen Oxidationsstufen
Authors: Boese Roland , Haas Alois , Herkt Silke , Pryka Michael
Published: July 2007

Perfluoroorganochalcogenic Acids in Higher Oxidation States

Pentafluoroethylseleninic acid is oxidized by KMnO4 in slightly alkaline aqueous solution to give K[C2F5SeO3]. With HClO4 the salt is converted into the free acid. Neutralisation of C2F5SeO3H with NaOH, Ag2O, NH3 + H2O provides the corresponding salts. The ethyl ester is made from Ag[C2F5SeO3] and C2H5I. Oxidation of C6F5TeC6F5 with concd. HNO3 yields C6F5Te(OH)ONO2 which on controlled hydrolyses gives (C6F5)2Te(OH)2. Strong acids like HClO4 or H2SO4 form mixed anhydrides like (C6F5)2Te(OH)ClO4 or (C6F5)2Te(OH)OS(O)2OTe(OH)(C6F5)2. For the latter compound a cyclic or noncyclic polycondensate form cannot be ruled out. Acidic 35% H2O2 solution oxidizes (C6F5)2Te(OH)2 at 40°C (48 h) to give (C6F5)2TeO2. This anhydride dissolves only in CF3SO3H forming (C6F5)2Te(OSO2CF3)4. It is soluble in CH3CN and reacts in solution with water to yield (C6F5)2Te(OH)2(OSO2CF3)2. Oxidation of C6F5TeTeC6F5 with concd. HNO3 provides oligomeric [C6F5Te(O)OH]x which still contains some HNO3. A single‐crystal X‐ray structure determination carried out on [(C6H5)4As][C2F5SeO3] shows convincingly that the central selenium atom is coordinated by three equivalent oxygen atoms with d(Se‐O) = 1.614(3) Å, proving that Se has the oxidation state VI.
Syntheses of Cyclic and Acyclic Bis(perfluoroalkylthio)nitronium Salts
Authors: Haas Alois , Waterfeld Alfred
Published: July 2007

(F3CS)3N (1) is oxidized quantitatively by AsF5 to the first bis(perfluoroalkylthio)nitronium salt (F3CS)2N+AsF−6 (2). Addition of halide ions (F−, Cl−, Br−, l−) to the cation of 2 destroys the SNS chain. (F2CSCl)2 undergoes with ammonia a cyclization reaction to SCF2CF2SNH (3), which can be derivatized with F3CSCl or (F2CSCl)2 to SCF2CF2SNSCF3 (3a) and (SCF2CF2SNSCF2)2 (3b), respectively. Oxidation of 3a with AsF5 yields (SCF2CF2SN+AsF−6 (4) and byproducts, which suggest formation of a {3a}+• radical cation as an intermediate in this reaction. Pure 4 is accessible by reaction of 3 with AsF5 in 54% yield. The chemical and spectroscopic properties of the new species are discussed.
About some Electrophilic Substitution Reactions with [(CF3S)3C+][AsF]
Authors: Haas Alois , Waterfeld Alfred , Klare Christiane , Möller Guido , Kondratenko Nataliya V. , Yagupolskii Lev M.
Published: July 2007

Tris(trifluoromethylthio)carbenium hexafluoroarsenate (1) reacts with N,N‐dimethylaniline and anisole to form the corresponding diphenylmethanes 2, 3 with the SCF3 group at the methine carbon atom. During the reaction of 1 with benzene, compounds such as C6H5C(SCF3)3 and C6H5SCF3 are formed along with benzophenone, a product of hydrolysis of the diphenylmethane compound.
Preparation and Molecular Structures of Tetrahydrofuran, Diethylene Diglycol Dimethyl Ether and 18‐Crown‐6 Complexes of Strontium and Barium Tetrahydridoborate
Authors: Bremer Mathias , Nöth Heinrich , Thomann Martina , Schmidt Martin
Published: July 2007

The strontium and barium tetrahydridoborate complexes M(BH4)2 · 2 diglyme and M(BH4)2 · 18‐crown‐6 (M = Sr, Ba) have been prepared from the solvates M(BH4)2 · 2 THF by ligand displacement. 11B‐NMR and IR data reveal strongly polar bonding of the BH4 groups to the metal centers, and X‐ray structural analyses of the diglyme and crown ether compounds show molecular units in which the BH4 group is in contact via three H atoms with the metal center. In contrast, M(BH4)2 · 2 THF compounds are chain polymers in the solid state, and each metal center is surrounded by 2 THF molecules in trans position and four BH4− groups each of which forms bridges with two metal centers. Estimations of the effective radius for the BH4 group indicate a high polarity for the M‐BH4 interaction.
Pyridyl‐Functionalised Cyclopentadienyl Ligands: Building Blocks for Oligonuclear Organometallic Assemblies
Authors: Siemeling Ulrich , Vorfeld Udo , Neumann Beate , Stammler Hans‐Georg
Published: July 2007

Lithiated 2‐methylpyridine reacts with 2,3,4,5‐tetramethylfulvene (TMF) to give 2‐[2‐(2,3,4,5‐tetramethylcyclopenta‐1,4‐dien‐1‐yl)ethyl]pyridine (2H) after aqueous work‐up. Similarly, a mixture of 2‐methyl‐6‐[2‐(2,3,4,5‐tetramethylcyclopenta‐1,4‐dien‐1‐yl)ethyl]pyridine (3H) and 2,6‐bis[2‐(2,3,4,5‐tetramethylcyclopenta‐1,4‐dien‐1‐yl)ethyl]pyridine (4H2) was obtained from monolithiated 2,6‐dimethylpyridine and TMF. All three compounds were obtained as a roughly statistical mixture of double‐bond isomers. 2‐Lithiopyridine reacts with 2,3,4,5‐tetramethylcyclopent‐2‐enone to yield 2‐(2,3,4,5‐tetramethylcyclopenta‐1,3‐dien‐1‐yl)pyridine (5H) after acidic work‐up. This compound was obtained as a non‐statistical mixture of double‐bond isomers, which is presumably due to intramolecular hydrogen‐bond interactions. The lithiated derivatives 2Li, 3Li and 5Li react with iron(II) chloride to afford the respective ferrocenes (2)2Fe (8), (3)2Fe (9) and (5)2Fe (10). The structure of 10 was determined by a single‐crystal X‐ray diffraction study. The cyclopentadienyl ligands adopt a staggered conformation; the pyridyl rings are arranged in a stacked fashion with the closest ring‐ring contact being 3.16 Å. The distance between the iron atom and the cyclopentadienyl ring centroids is 1.66 Å.
On the Chemistry of Gallium, V. Cyclic Compounds of Gallium and Indium with the 2,2‐Dimethyl‐1,3‐bis‐[(trimethylsilyl)amino]propane Ligand
Authors: Linti Gerald , Nöth Heinrich , Polborn Kurt , Robl Christian , Schmidt Martin
Published: July 2007

Reaction of 2,2‐Dimethyl‐N‐lithio‐1,3‐bis[(trimethylsilyl)amino]propane (4a) with RGaBr2 (R = Br, Mes) allows the isolation of the cyclic monomeric amine(amino)gallanes 5 and 6. The cyclic bis(amino) gallanes 7 and 9 as well as the indium homologue 10 were obtained by reaction of gallium halides RGaCl2 (R = Cl, Mes) or InCl3 with dilithiated 4. In the case of R = Mes the product is a monomer. In addition, the tetrakis(amino)gallate 8 was isolated. Single‐crystal X‐ray diffraction studies confirmed the constitutions. Compound 5 has one short GaN single bond (184 pm) and a longer GaN dative bond (204 pm). Compound 7 exhibits a central asymmetrical four‐membered Ga2N2 ring [d(GaN) = 199.4, 205.6 pm] with syn‐oriented substituents. The terminal GaN bond length is 184.3 pm. Two nitrogen atoms bridge the lithium and gallium atom in the gallate 8 [d(LiN) = 206 pm]. Two Li‐H contacts complete the coordination sphere at the lithium atom.
Metallkomplexe unsymmetrisch überbrückter [N4]‐Makrocyclen: Synthese, Struktur und Redoxverhalten
Authors: Jäger Ernst‐Gottfried , Keutel Heike , Rudolph Manfred , Krebs Bernt , Wiesemann Frank
Published: July 2007

Metal Complexes of Unsymmetrically Bridged [N4] Macrocycles: Synthesis, Structure and Redox Behaviour

Metal complexes M‐5a (M = Cu, Ni, Co, Fe, and I‐Fe11) of 6,13‐Di(ethoxycarbonyl)‐7,12‐dimethyl‐benzo[b]‐1,4,8,11‐tetraaza‐cyclotetradeca‐2,5,7,11,13‐pentaene and the free ligand H2‐5a have been synthesized. The crystals of Cu‐5a · H2O and Ni‐5a · H2O consist of planar complex molecules which are linked by H bridges between the water molecules and the peripheric ester groups to give 1D chains. The average M‐N distances are equal for both complexes (Cu 1.928, Ni 1.924 Å), being unexpectedly large for the nickel complex. The redox properties of all the new compounds as well as some acetyl derivatives M‐5b have been examined by cyclic voltammetry and compared with those of the previously reported symmetrically phenylene (M‐4) and ethylene (M‐6) bridged derivatives. All complexes give a reversible single electron reduction which clearly shows the increasing electron density around the central atom in the order M‐4 < M‐5 < M‐6. Like the carbonyl substituted tetraazaannulenes M‐4 the copper complexes Cu‐5 give two, the cobalt complexes Co‐5 three, and the iron complex Fe‐5a probably four reversible single electron oxidations. They can be attributed to the species [MIIIL−II]+, [MIILo]2+, [MIIILo]3+, and [FeIVLo]4+ with Lo being a “non innocent” neutral 1,2‐quinodiimine ligand. Very surprisingly, since in contrast to Ni‐4 and Ni‐6, the nickel complexes Ni‐5 gave no reversible oxidation.
Sulfur Compounds, Part 186. The Synthesis of Cyclic Organosulfur Compounds from (C5H5)4Ti2C2S4 by Ligand Transfer Reactions
Authors: Steudel Ralf , Westphal Ursula , Pickardt Joachim
Published: July 2007

The tetrathiaoxalate complex Cp4Ti2C2S4 (1) reacts with an equimolar amount of COCl2 to give the blue‐green mononuclear complex Cp2TiC2S4CO (4). This reaction is analogous to the known reactions of 1 with SCl2 or S2Cl2. However, when 1 was treated with equimolar amounts of the bifunctional sulfenyl chlorides 1,2‐C2H4(SCl)2 (5), 1,3‐C3H6(SCl)2 (6) or 1,2‐C6H4(SCl)2 (7), the bi‐ or monocyclic tetrakisdisulfanes C6H8S8 (9b), C8H12S8 (10), and C14H8S8 (11), respectively, were obtained. The X‐ray crystal structure analysis of 11 · CS2 showed that 11 possesses Ci symmetry with a central exocyclic CC double bond similar to tetrathiafulvalenes: C6H4(μ‐S2)2CC(μ‐S2)2C6H4.
Synthesis and Crystal and Molecular Structure of Tris(dimethylphenylsilyl)antimony
Authors: Sladek Alexander , Schmidbaur Hubert
Published: July 2007

Tris(dimethylphenylsilyl)antimony (1) was prepared in moderate yield from dimetallic “Na3Sb” (generated in situ) and chlorodimethylphenylsilane in tetrahydrofuran at reflux temperature. The product was identified by standard analytical and spectroscopic techniques, and the crystal structure was determined by single‐crystal X‐ray diffraction (triclinic, space group P1, Z = 2). The SbSi3 skeleton is pyramidal (average Si‐Sb‐Si angle 100.2°, average Sb‐Si bond length 2.558 Å), and the Me2PhSi groups are in a staggered conformation.
Soluble Substituted μ‐Oxo(phthalocyaninato)iron(III) Dimers
Authors: Dieing Reinhold , Schmid Gabriele , Witke Elisabeth , Feucht Carola , Dreßen Michael , Pohmer Jörg , Hanack Michael
Published: July 2007

Attempts to prepare various peripheral tetra‐ and octasubstituted (phthalocyaninato)iron derivatives RnPcFe [n = 4: R = CH2OEt (6e), CO2Et (6h), CO2‐n‐C6H13 (6l), O(2‐Et‐n‐C6H13) (6j), OCH2C(CH3)3 (6k), OCH2C(CH3)2CH2Ph (6l); n = 8: R = CH2CH(CO2Me)CH(CO2Me)CH2 (6f), CH2CH(CO2Et)‐CH(CO2Et)CH2 (6g), O‐n‐C8H17 (6m), O(2‐Et‐n‐C6H13) (6n)] by starting from the corresponding substituted phthalonitriles led to substituted (μ‐oxo)bis[(phthalocyaninato)iron(III)] compounds [RnPcFe]2O. The tert‐butyl‐ and ethyl‐substituted systems [tBu4PcFe]2O (6c) and [Et4PcFe]2O (6d) were reinve‐stigated. UV/Vis, FD mass, Mössbauer, NMR as well as ESR spectroscopy was used to characterize the complexes [RnPcFe]2O to furnish evidence for the presence of Fe‐O‐Fe moieties in [RnPcFe]2O. The UV/Vis data reported for [RnPcFe]2O as well as their spectral behavior in pyridine correspond to unsubstituted [PcFe]2O. Mössbauer spectra of [RnPcFe]2O show that the complexes were obtained as a mixture of two isomeric μ‐oxo compounds A (δFe = 0.22 mm s‐1, ΔEQ = 1.33–1.39 mm s‐1) and B (ΔFe = 0.33–0.36 mm s‐1, ΔEQ = 0.39–0.53 mm s‐1), whose Mössbauer parameters are comparable to [PcFe]2O μ‐oxo(2) and μ‐oxo(1), respectively. Mössbauer spectral data of [RnPcFe]2O indicate high‐spin (S = 5/2) FeIII centers. NMR‐spectra of [RnPcFe]2O (n = 4: R = tBu, Et, O(2‐Et‐n‐C6H13), OCH2C(CH3)2CH2Ph; n = 8: R = O‐n‐C8H17, O(2‐Et‐n‐C6H13) give further evidence for μ‐oxo bridged structures.
Syntheses, Structures, and Equilibria of o‐, m‐, p‐Tolyl‐ and Phenylantimony Rings
Authors: Breunig Hans Joachim , Ebert Klaus Heinz , Gülec Sabahittin , Probst Joachim
Published: July 2007

Exchange reactions of R3Sb (R = o‐Tol, m‐Tol, p‐Tol) with SbCl3 in a 1:2 molar ratio give RSbCl2. Silylstibanes RSb(SiMe3)2 were obtained by reaction of RSbCl2 and Me3SiCl with Mg in THF. Slow access of air to solutions of RSb(SiMe3)2 afforded orange crystals of the composition (RSb)n. Crystal structures were determined by X‐ray crystallography for R = o‐Tol and m‐Tol as stacks of (RSb)6 rings in the chair conformation with equatorial substituents. In the crystals of (m‐TolSb)6 there are short intermolecular Sbb distances of 420 pm. Solutions of (RSb)n (R = Ph, o‐Tol, m‐Tol, p‐Tol) in C6D6 were analyzed by 1H‐NMR spectroscopy. They contain (RSb)5 and (RSb)4 in equilibria. Raman spectra of (PhSb)6 or (p‐TolSb)n show signals for Sbn at β = 151 or 153 cm‐1. 13C‐CP‐MAS‐NMR data of (p‐TolSb)n are reported.
Reactions of Complex Ligands, LXV. Vinylidene and Methoxy(alkynyl)carbene Molybdenum Complexes: Competitive Formation During Fischer Carbene Complex Synthesis and Crystal Structure Determination
Authors: Dötz Karl Heinz , Christoffers Carmen , Christoffers Jens , Böttcher Dirk , Nieger Martin , Kotila Sirpa
Published: July 2007

Reaction of [(η5‐C5H5)(CO)2(NO)Mo] (1) with alkynyllithium and [(CH3)3O]BF4 affords the vinylidene‐molybdenum complex 2 along with the methoxy(alkynyl)carbene molybdenum complex 3. Both compounds are characterized by an X‐ray crystal structure analysis. Due to axial and central chirality in the LnMCCR2 moiety complex 2 is formed as a 2 : 1 mixture of two diastereomers. The formation of 2 and 3 can be understood in terms of a competitive attack of alkynyllithium at the carbonyl ligand and the molybdenum center.
Ligand‐Induced Directionality Shift in the Fe+‐Mediated Dehydrogenation of 1,8‐Diphenyloctane
Authors: Raabe Norbert , Karraß Sigurd , Schwarz Helmut
Published: July 2007

The presence of a cyclopentadienyl ligand brings about a complete shift of regioselectivity in the Fe+‐mediated dehydrogenation of 1,8‐diphenyloctane (1). While “bare” Fe+, due to the formation of an intramolecular sandwich‐like complex, activates the internal C‐4/C‐5 positions of the alkyl chain, this chelate effect is no longer operative in the gas‐phase chemistry of Fe(C5H5)+ with 1. Labeling experiments demonstrate that the C‐1/C‐2 and (to a minor extent) the C‐2/C‐3 methylene groups are activated, and a possible origin of this remarkable ligand effect is discussed.
Crystal Structure of CF3SNSO‐AsF5
Authors: Brosius Axel , Haas Alois
Published: July 2007

Reinvestigation of an earlier reported preliminary X‐ray structure verifies the coordination of AsF5 to the oxygen atom of CF3SNSO. The resulting differences in bond lengths of the cumulene system SNSO via an attachment of the Lewis acid are mentioned.
Synthesis, Structure, and Ligand Behavior of the 1,2‐Diphosphaferrocene [η5‐1,3‐tBu2C5H3)(η5{3,4‐(Me3Si0)2‐5‐(Me3Si)P2C3} Fe]
Authors: Weber Lothar , Sommer Oliver , Stammler Hans‐Georg , Neumann Beate , Kölle Ulrich
Published: July 2007

Reaction of equimolar amounts of (η5‐1,3‐tBu2C5H3)(CO)‐{3,4‐(Me3SiO)2‐5‐(Me3Si)P2C3}Fe]2‐FeP(SiMe3)2 with bis(trimethylsilyl)methylenechlorophosphane afforded the 1‐metallo‐1,2‐diphosphapropene (η5‐1,3‐tBu2C5H3)(CO)2 FeP (SiMe3)P = C(SiMe3)2 (1b). Treatment of 1b with an excess of [(Z)‐cyclooctene]Cr(CO)5 furnished 1,2‐diphosphaferrocene (η5‐1,3‐tBu2C5H3)(η5‐{1‐[Cr(CO)5]‐3,4‐(Me3SiO)2‐5‐(Me3Si)P2C3}Fe (4b). Chromium complex 4b was freed from the pentacarbonylchromium fragment by heating with 1.5 equiv. of [Fe2(CO)9] in toluene solution at 80–90°C affording sandwich 5. In contrast, treatment of 4c with [Fe2(CO)9] in refluxing n‐pentane yielded the trinuclear complex (η5‐1,3‐tBu2C5H3){η5‐1,2‐[Fe2(CO)7]‐3,4‐(Me3SiO)2‐5‐(Me3Si)P2C3}Fe (6). The ligation of sandwich 5 to the [Fe(CO)4] unit in 7 was achieved by irradiation with [Fe(CO)5] in n‐pentane solution. A tricarbonylnickel adduct 8 resulted from the reaction of 4b with an excess of [Ni(CO)4] in toluene at ambient temperature. The molecular structures of the complexes 6 and 8 were established by single‐crystal X‐ray structure analyses. Cyclovoltammetric studies with 4b, 5, and 8 revealed an anodic shift of the oxidation potential when changing from 5 to 8 and 4.
1,1′‐Bis(methylphenylphosphanyl)ferrocene: Synthesis and Complexes with the Tetracarbonylchromium Fragment
Authors: Herberich Gerhard E. , Moss Stefan
Published: July 2007

1,1′‐Bis(methylphenylphosphanyl)ferrocene (mppf) (2) was synthesized from dilithioferrocene and PMePh(OC6H4‐4‐Me). The diastereomers rac‐2 and meso‐2 were separated by fractional crystallization from ethanol. The tetracarbonyl‐chromium complexes (rac‐2)Cr(CO)4 (rac‐5) and (meso‐2)Cr(CO)4 (meso‐5) were obtained photochemically from hexacarbonylchromium and mppf in near quantitative yield. The structures of rac‐2, rac‐5, and meso‐5 were determined by X‐ray crystallographic analysis.
Synthesis and Complexation Behavior of the Functionalized Tripodal Phosphane cis,cis‐1,3,5‐Tris(cyano)‐1,3,5‐tris(diphenylphosphanyl)‐cyclohexane (tdppcycn)
Authors: Mayer Hermann A. , Stößel Philipp , Fawzi Riad , Steimann Manfred
Published: July 2007

The synthesis of the novel potentially bistripodal ligand cis‐cis‐1,3,5‐tris(cyano)‐1,3,5‐tris(diphenylphosphanyl)cyclohexane (tdppcycn) (6) is described. Starting from the tricarboxylic acid cis,cis‐1,3,5‐C6H9(COOH)3 (1), which is converted stepwise into the triacid chloride cis,cis‐1,3,5‐C6H9(COCl)3 (2), the triphenyl ester cis,cis‐1,3,5‐C6H9(COOPh)3 (3), the tricarboxamide cis,cis‐1,3,5‐C6H9(CONH2)3 (4), and the tricarbonitrile cis,cis‐1,3,5‐C6H9(CN)3 (5), we obtained tdppcycn (6) by α‐deprotonation of 5 followed by treatment with ClPPh2 in good yield. Treatment of 6 with Mo(CO)3(‐C7H8) and Ir(PPh3)2(CO)Cl gave octahedral Mo(tdpp‐cycn)(CO)3 (7) and pentacoordinate Ir(tdppcycn)(CO)Cl (8), respectively, with a facially P‐coordinated tdppcycn ligand. The stereochemistry of compounds 2–8 was established by 1H‐, 13C‐, 31P‐NMR, and IR spectroscopy. An X‐ray crystal structure analysis of complex 8 confirms the trigonal‐bipyramidal ground‐state structure in the solid state.
A Direct Route to Halogenated Arsaborane Clusters: Crystal Structure of 3,4,5,6‐Tetrachloro‐1,2‐diarsa‐closo‐hexaborane(4)
Authors: Schäfer Ronald , Einholz Wolfgang , Keller Willi , Eulenberger Günther , Haubold Wolfgang
Published: July 2007

Copyrolysis of B2Cl4 and AsCl3 at 330°C leads to the formation of closo‐1,2‐As2B4Cl4 (1) and further products the mass spectral evidence of which suggests that they are perchlorinated arsaboranes As2B5Cl5, As4B8Cl6, and As2B10Cl10. The pyrolysis temperature and the molar ratio of the reactants exert an essential influence on the type and distribution of the products. At temperatures above 400°C and higher B2Cl4/AsCl3 ratios the formation of As2B10Cl10 is preferred to that of smaller arsaboranes. A single‐crystal X‐ray study of 1 confirmed that, consistent with its 14‐skeletal electron count, the arsaborane adopts a slightly distorted octahedral structure with the arsenic atoms in adjacent cis positions.
Synthesis of Structures of (Acyloxy)boranesSynthesis of Structures of (Acyloxy)boranes
Authors: Lang Andreas , Nöth Heinrich , Schmidt Martin
Published: July 2007

9‐Borabicyclo[3.3.1]nonane (9‐BBNH) reacts with monocarboxylic acids to afford 9‐(acyloxy)‐9‐borabicyclo[3.3.1]nonanes which are dimers in the solid state as shown by X‐ray crystal structures of the benzoate and pivalate. More complex reactions were observed by allowing 9‐BBNH to react with dicarboxylic acids in THF or monoglyme. Thus, (9‐BBN)2 oxalate 3 contains a fully delocalized oxalate unit with equal C‐O and B‐O bond lengths. Traces of water convert it into the tetrakis(9‐BBN) oxalate 5. A rather unusual structure is veryfied by 9‐BBN 2,2‐dimethylmalonate 7 which according to its molecular structure is a tetramer featuring a 32‐membered ring system. In contrast, reactions of oxalic acid with thexylborane leads to reduction of the acid and formation of a bicyclic dioxaborolo‐dioxaborolane 10. Several intermediates were detected by 11B‐NMR spectroscopy as well as in reactions of BH3 · THF or BH3 · SMe2 with oxalic acid. — It follows from the present study that (acyloxy)boranes derived from dicarboxylic acids are strong Lewis acids with an unexpected variety of structural features.
Chalcogen Polycations with Mononuclear Divalent Anions from Chalcogen Subhalides and Tetrachlorides of Zr and Hf: Syntheses and Crystal Structures of Se4(MCl6) (M = Zr, Hf) and Te4(HfCl6)
Authors: Beck Johannes , Schlitt Klaus‐Jürgen
Published: July 2007

Selenium, SeCl4, and MCl4 (M = Zr, Hf) react in a sealed evacuated glass ampoule at 130°C to afford red, moisture sensitive crystals of Se2+4(ZrCl2‐6) and Se2‐6(HfCl2‐6). The isotypic crystal structures (tetragonal, P42/ncm, Z = 4) consist of square‐planar Se2+4 cations and slightly distorted octahedral MCl2‐6 (M = Zr, Hf) anions. The ions are packed corresponding to the NaCl structure type with the centres of gravity of the Se4 rings and the metal atoms of the MCl6 octahedra in the Na and Cl positions. From Te, TeCl4, and HfCl4 one obtains under similar conditions at 200°C Te2+4 (HfCl2‐6) in form of dark violet crystals. The crystal structure (triclinic, P1, Z = 1) is built of nearly square‐planar Te2+4 ions and octahedral HfCl2‐6 ions. The packing of the ions corresponds to a rhombohedrally distorted CsCl structure type.
β‐Alkoxy‐ and β‐Hydroxyalkylphosphanes as Ligands in the Stereoselective Hydrogenation — A Comparison
Authors: Börner Armin , Kless Achim , Kempe Rhett , Heller Detlef , Holz Jens , Baumann Wolfgang
Published: July 2007

Optically pure 1,4‐bis(diphenylphosphanyl)‐2‐hydroxy‐butane (2) and its methyl ether 1 can be conveniently prepared by starting from chiral pool substances such as malic or L‐ascorbic acid. Different pathways to these compounds were elucidated. In one case an interesting migration of an acetalic OH‐protective group was observed. The reaction of the bisphosphanes with Rh1 or PdII gave uniform metal complexes. On the basis of X‐ray structural analysis, NMR and IR data it was concluded that in the investigated precatalysts of the type [Rh(COD)(bisphosphane)]BF4 a coordination of the alkoxy or hydroxy oxygen to the metal does not take place. Nevertheless, significant differences in enantioselectivity and activity could be observed when several prochiral substrates were hydrogenated.
Zinc Complexes of Drugs Containing Nitrogen Heterocycles
Authors: Koppenhöfer Alrik , Hartmann Uwe , Vahrenkamp Heinrich
Published: July 2007

Four drugs whose actions have a relation to the status of zinccontaining species in the human body were used as ligands in zinc complexes. Captopril (H2Cap) forms the compound [ZnCap] (1) presumed to be a coordination polymer with O and S coordination. Isoniazid, in the presence of zinc salts, is converted to 1,2‐diisonicotinoyl hydrazide (H2Nih) which forms polymeric [Zn(Nih)NH3] (2) with trigonal‐bipyramidal ZnO2N3 coordination. Nalidixic acid (HNal) and zinc perchlorate yield [Zn(HNal)2(H2O)2](ClO4)2 · 2 H2O (3) containing zinc in an octahedral ZnO6 environment. Mercaptopurine (H2Mer), in the presence of ammonia, forms [Zn(Mer)(NH3)2] . H2O (4) which is a coordination polymer containing tetrahedral ZnN4 units. The structures of [Zn(Nih)NH3], [Zn(HNal)2(H2O)2](ClO4)2 . 2 H2O, and [Zn(Mer)(NH3)2] . 2 H2O were determined diffractometrically.
Locating the Position of Lithium in Solution by Combined 13C,6Li and 1H,6Li HOESY Measurements
Authors: Berger Stefan , Müller Frank
Published: July 2007

13C,6Li HOESY Measurements were developed and performed for the first time on the 13C‐labeled benzyllithium compound 1. 1D NOE difference, 1H,6Li HOESY, and spin lattice relaxation measurements were used to obtain information on the position of the lithium, ion in solution.
Enantioselective Deprotonation of Benzyl Phosphates by Homochiral Lithium Amide Bases — Configurational Stability of Benzyl Carbanions with a Dialkoxyphosphoryloxy Substituent and Their Rearrangement to Optically Active α‐Hydroxy Phosphonates
Authors: Hamerschmidt Friedrich , Hanninger Achim
Published: July 2007

Benzyl dialkyl phosphates are deprotonated enantioselectively by homochiral lithium amides of isopropyl(1‐phenylethyl)amine or bis(1‐phenylethyl)amine. The short‐lived benzylic carbanions formed are virtually configurationally stable relative to the rearrangement to optically active phenyl‐hydroxymethylphosphonates. The enantiomeric excesses are up to 50%. The pro‐(S) hydrogen is removed by amides having (S) configuration. Homochiral diethyl (S)‐phenyl[D1]‐methyl phosphate [(S)‐16c] is deprotonated by both LDA and n‐BuLi with a high primary kinetic isotope effect (kH/D ≈︁ 50) and isomerizes to the corresponding α‐hydroxy phosphonate with an enantiomeric excess of up to 85%.
Tris(1,10‐phenanthroline)iron(II) Complexes — Broad Variation of the Redox Potential by 4,7‐Substitution at the Phenanthroline Ligands[1]
Authors: Schmittel Michael , Ammon Horst , Wöhrle Clemens
Published: July 2007

The new 4,7‐donor‐substituted phenanthrolines 2a‐h were synthesized and the corresponding tris(1,10‐phenanthroline)iron(II) complexes 3a‐h studied by cyclic voltammetry. In more detail three novel aza‐crown ether‐linked (phenanthroline)iron complexes were investigated, the redox potentials of which could be fine‐tuned by the addition of group‐Ia,IIa metal cations. All iron(II) complexes showed reversible waves at scan rates between 50 and 500 mV · s‐1 and could be reversibly oxidized and reduced by chemical means.
Synthesis of Allenes by 1,6‐Addition of Organocuprates to Acceptor‐Substituted Enynes: Scope and Limitations
Authors: Hohmann Michael , Krause Norbert
Published: July 2007

Acyclic acceptor‐substituted conjugated enynes bearing sulfonyl sulfinyl, sulfonate, nitro, amide, cyano, and oxazolidino groups at the double bond were synthesized and the regioselectivity of their reaction with organocuprates was examined. All Michael acceptors except enynes with nitro and amide functions underwent 1,6‐additions, and the allenyl enolates thus formed were trapped with electrophiles in order to obtain the corresponding allenes. A qualitative reactivity scale for these reactions was established. The dependence of the regioselectivity of both the cuprate addition and the subsequent electrophilic capture on the acceptor group and the substitution pattern of the allenyl enolate were studied. Cyclic 2‐en‐4‐ynoates with endocyclic double bonds were synthesized and treated with organocuprates to afford an exocyclic allene in one case.
Thiono, Selenothiono, and Dithiocarboxylic Ester Complexes from Pentacarbonyl(thiobenzaldehyde)tungsten and π‐Donor Substituted Alkynes and Decomplexation of the Esters
Authors: Fischer Helmut , Treier Kornelia , Troll Carsten
Published: July 2007

Pentacarbonyltungsten‐coordinated thiobenzaldehyde, [(CO)5W{S=C(Ph)H}] (1), reacts with 1‐methylthio‐1‐propyne, 1‐ethylseleno‐1‐propyne, and alkoxyethynes by insertion of the CC into the S=C bond to form in a highly regio‐and stereoselective manner the α,β‐unsaturated dithio, selenothiono, and thionocarboxylic ester complexes (E)(CC)‐[(CO)5W{η1‐SC(XR′)C(R)=C(Ph)H}] (3) (R = Me: XR′ = SMe (a), SeEt (b); R = H: XR′ = OEt (c), OtBu (d)). The analogous reaction of 1 with bis(alkylthio)ethynes affords mixtures of the (E) and (Z)(C=C) isomers of [(CO)5W{η1‐S=C(SR)C(SR)=C(Ph)H}] (6) [R = Me (a), tBu (b)]. The Z isomers are the initially formed products. Formation of (Z)‐6 is followed by Z → E isomerization until an equilibrium [E/Z = 1 (6a), 1.5 (6b)] is obtained. For R = tBu isomerization is significantly faster than for R = Me. The dithio and thiono ester ligands can be cleaved intact from the metal by treatment with [NEt4]Br as shown by the examples of 3a, 3c, and 6a. Complex 3c has been characterized by an X‐ray structural analysis.
Metal Tetrahydroborates and Tetrahydroborato Metalates. 20. Reactions of Cadmium Tetrahydroborate with Alcoholates and Phenolates ‐ X‐ray Structure of [MeCd(OCMe3)]4
Authors: Nöth Heinrich , Thomann Martina
Published: July 2007

Cadmium tetrahydroborate reacts with alkali metal alcoholates or phenolates in THF solution either with formation of addition products [Cd(BH4)2OR]‐ or by ligand exchange to produce Cd(BH4)OR. Different oligomers of the latter are formed depending on concentration. The reaction of Cd(BH4)2 with Cd(Omes)2 (mes = mesityl) leads to an equilibrium of the starting materials with Cd(BH4)(Omes) as shown by 113Cd‐NMR spectroscopy. The crystal structure of Me‐Cd(OCMe3), a molecule which can be regarded as a model for Cd(OCMe3)(BH4), proved to be a tetramer with a cubane‐type Cd4O4 core.
Silicon Compounds with Strong Intramolecular Steric Interactions. LVII. Oxidation and Cycloaddition Reactions of an Unsymmetrically Substituted Disilene
Authors: Weidenbruch Manfred , Pellmann Andrea , Pohl Siegfried , Saak Wolfgang , Marsmann Heinrich
Published: July 2007

Reaction of the unsymmetrically substituted disilene R2Si=SiR′2 (4; R = 2,4,6‐Me3C6H2, R′ = 2,4,6‐iPr3C6H2) with m‐chloroperbenzoic acid (mCPBA) or oxygen furnished the correspondingly substituted 1,2,3‐oxadisilirane 5 or 1,3,2,4‐dioxadisiletane 6, respectively. The [2 + 2] and [2 + 4] Cycloaddition reactions of 4 with benzophenone and 3,5‐di‐tert‐butyl‐1,2‐benzoquinone, respectively, proceeded with a high degree of regioselectivity to yield the 1,2,3‐oxadisiletane 9 and the 2,3‐dihydro‐1,4,2,3‐benzodioxadisiline 7. The latter product was isolated together with a small amount of an isomeric compound 8 in which the substituents at the silicon atoms are reversed. The molecular structures of the products 5, 6, and 7 were determined by X‐ray crystallography.
Norbornadiene(bipyridyl)molybdenum(II) Complexes: Synthesis, Structure and Reactivity of [Mo(CO)(C7H8)(C10H6R2N2)X2] (X = I, Br)
Authors: Daniel Thomas , Nagao Hirotaka , Tanaka Koji , Nakamura Akira
Published: July 2007

The reaction of [Mo(CO)4(C7H8)] (1) with I2 gave the norbornadienemolybdenum(II) complex [Mo(CO)2(C7H8)I2]n≥1 (2), which existed in an equilibrium of two isomeric forms. In acetonitrile, 2 reversibly formed the adduct [Mo(CO)2‐(C7H8)(NCCH3)I2] (3), whereas on treatment with 2,2′‐bipyridine or 4,4′‐di‐2,2′‐tBu‐bipyridine, it gave stable 7‐coordinated molybdenum(II) complexes, [Mo(CO)(C7H8)‐(C10H8N2)I2] (4) and [Mo(CO)(C7H8)(C10H6tBu2N2)I2] (5), in good yield. In similar reactions, the related dibromomolybdenum compounds [Mo(CO)(C7H8)(C10H8N2)Br2] (6) and [Mo‐(CO)(C7H8)(C10H6tBu2N2)Br2] (7) were prepared by oxidation of 1 with two equivalents of CuBr2. The X‐ray structural analysis of 6 reveals that the geometry around the molybdenum atom is nearly perfectly pentagonal bipyramidal, with the CO and one of the bipyridyl rings perpendicular to the plane formed by the other ligands. The compounds 5 and 6 react with AgSbF6 by halogen abstraction to give cationic complexes, {[Mo(CO)(C7H8)(C10H8N2)Br]SbF6}n≥1 (8) and {[Mo(CO)(C7H8)(C10H6tBu2N2)I]SbF6}n≥1 (9): In acetone, 8 and 9 reversibly formed the adducts [Mo(CO)(C7H8)(C10H8N2)(acetone)Br]SbF6 (8′) and [Mo(CO)(C7H8)(C10H6tBu2N2)(acetone)I]SbF6 (9′); while on treatment with PMe3, the stable monomeric complexes, [Mo(CO)(C7H8)(C10H8N2)(PMe3)Br]SbF6 (10) and [Mo(CO)(C7H8)(C10H6tBu2N2)(PMe3)I]SbF6 (11), were isolated in almost quantitative yield. In the presence of KBr, compound 8′ reverted to the dibromo complex 6, whereas 9′ reacted to produce a 1:1:2 mixture of 5, 7 and the bromo(iodo) complex [Mo(CO)(C7H8)(C10H6tBu2N2)BrI] (12). The same mixture is available from the reaction of 5 with one equivalent of 7.
Functionalized Diorganozinc Compounds: Key Reagents for the Synthesis of Enantiomerically Pure 2,5‐Disubstituted cis‐ and trans‐Tetrahydrofurans
Authors: Berninger Jörn , Koert Ulrich , Eisenberg‐Höhl Christina , Knochel Paul
Published: July 2007

1,4‐Diol derivatives 4a‐i were synthesized stereoselectively by either reagent‐ or catalyst‐controlled routes using the addition of functionalized diorganozinc reagents to aldehydes. The stereoselectivities along the reagent‐controlled synthetic path were in the range between 80:20 and 95:5. The stereoselectivities along the catalyst route exceeded 95:5. The 1,4‐diol derivatives 4 thus obtained were transformed into enantiomerically pure cis‐ and trans‐2,5‐disubstituted tetrahydrofurans (16‐20) by means of an intramolecular Williamson reaction.
Titanocene Complexes Based on Benzenehexathiolate Derivatives and 2,3,6,7‐Tetrachloronaphthalenetetrathiolate
Authors: Fanghänel Egon , Bierwisch Jörg , Ullrich Andreas , Herrmann Anett
Published: July 2007

The synthesis and properties of the new (dithiolato)titanocene complexes 4a‐d, 6, 9 are described. The ligands of these complexes are derived from sodium benzenehexathiolate or 3,4,7,8‐tetrachloronaphthobis[1,2]dithiole. Complexes with one, two and three (dithiolato)titanocene units were prepared by use of these dithiolato ligands.
Amino Substituted Tricarbonyl(cyclobutadiene)iron Complexes: Pd‐Catalyzed Coupling of Iodocyclobutadiene Complexes with Amines
Authors: Wiegelmann‐Kreiter Jutta E. C. , Enkelmann Volker , Bunz Uwe H. F.
Published: July 2007

The coupling of the iodides 1 with amines under palladium catalysis affords the novel aminated cyclobutadiene derivatives 2 in preparative useful yields.
Metallocenophanes, VII. Preparation and Characterisation of the Disilver(I) Complexes of Conjugated Polyenes with [2.2.2]Paracyclophanyl End Groups
Authors: Heirtzler Fenton R. , Hopf Henning , Bubenitschek Peter , Jones Peter G.
Published: July 2007

The preparation of the disilver(I) complexes 3 and 4, polyene metal complexes that are terminally substituted with [2.2.2]paracyclophanyl units, is described. NMR spectro‐scopic studies on the disilver perchlorate complex 3b showed that (a) the sites of complexation are the cyclophane groups and (b) the olefinic spacers do not overly perturb the overall complexation properties of the individual [2.2.2]paracyclo‐phanyl groups. The crystal structures of the disilver hexafluo‐roantimonate complexes 4a–b were determined. The use of the hexafluoroantimonate counterion and solvent mixtures containing toluene both proved crucial in obtaining single crystals; toluene is incorportated into the crystal lattices.
Unusual Complexation Behavior of Metallomacrocycles Based on Isothiosemicarbazides with Respect to Alkali and Alkaline Earth Metal Ions: Novel 2:1 Associates
Authors: Reetz Manfred T. , Arion Vladimir B. , Trültzsch Rainer , Buschmann Hans‐Jürgen , Cleve Ernst
Published: July 2007

The reactions between alkali and alkaline earth metal ions and nickel(II) macrocycles based on S‐alkylated isothiosemi‐carbazides with different crown ether cavity size were studied in propylene carbonate by spectrophotometric and calorimetric titrations. Metallomacrocycles 1 and 2 exhibit normal behavior on 1:1 complexation with alkali‐ and alkaline earth metal ions and resemble in this respect 15C5 and 18C6, respectively. The most stable complexes are formed by these “ligands” when the diameter of the cation and the crown ether hole have approximately the same size. The most striking feature of the complexation processes studied is the formation of 1:2 metal‐ligand associates even in the case of the smallest cations. These associates are very different from “normal” crown ether sandwich complexes. In reality, the particle formed is an associate between a 1:1 complex, in which the corresponding metal ion is well accommdated inside the ligand cavity, and a second metallomacrocyclic ligand. Their formation is disfavored by enthalpic contributions. A special kind of “switch” from these associates to normal sandwich complexes takes place in the case of 1, when the cation diameter compared to hole size increases. The macrocycle 2 forms this kind of associates with all akali and alkaline earth ions.