bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthese und Charakterisierung neuer Hemiporphyrazinato‐Nickelkomplexe
Authors: Haberroth Klaus , Rack Michael , Ruff Detlef , Hanack Michael
Published: July 2007

Synthesis and Characterization of New Hemiporphyrazinato Nickel Complexes

The new substituted (hemiporphyrazinato)nickel complexes [HpNi] 3–9 and 11–14, the (heminaphthoporphyrazinato)‐nickel complexes 15–19 [HnpNi], and the hemianthraceno‐phorphyrazine complex [HapNi] 20 are prepared from isoin‐dolenines 1a–e and 10a–d, diaminopyridines 2a–e and nickel acetate. The compounds were characterized by 1H‐ and 13C‐NMR spectroscopy. The 1H‐NMR spectrum of the mixture of the 3,18/3,19‐substituted (C2v/C2h) complexes is discussed.
Syntheses and Properties of X6Te2N2Se (XCl, Br): Stable Heterocycles with an NSeN Moiety
Authors: Haas Alois , Schäfers Mike
Published: July 2007

Treatment of Se[N(SiMe3)2]2 with TeX4 (XCl, Br) yields new bicyclic tellura heterocycles X6Te2N2Se (XCl, 1a; XBr, 1b). Similarly, these compounds are obtained with elimination of elemental selenium by reaction of Se2‐[N(SiMe3)2]2 with TeX4 (XCl, Br). They are characterized by IR and mass spectroscopy as well as elemental analyses. 125Te‐ and 77Se‐NMR data are given for Cl6Te2N2Se (1a), and spectra are compared with those of the corresponding sulfur analogs.
Synthesis and Structure of the First Dimetalated Diphosphane Disulfide [(η5‐C5Me5)(CO)2FeP(H)(S)]2
Authors: Weber Lothar , Misiak Hanns , Stammler Hans‐Georg , Neumann Beate
Published: July 2007

The first transition metal derivative meso‐[(η5‐C5Me5)(CO)2FeP(H)(S)]2 (2) of the unknown diphosphane disulfide [PH2(S)]2 results from treatment of (η5‐C5Me5)(CO)2FePH2 (1) with 1.5 equivalents of elemental sulfur. Compound 2 was characterized by means of spectroscopy (IR, 31P, 31P{1H}, 13C{1H}, 1H NMR) as well as X‐ray diffraction analysis.
Chiral Organometallic Reagents, XIII. Structural Aspects of Differentially Solvated Benzyllithium Contact Ion Pairs
Authors: Ruhland Thomas , Hoffmann Reinhard W. , Schade Steffen , Boche Gernot
Published: July 2007

The solvation and ion pair nature of α‐(phenylthio)benzyllithium (2d) in THF solution were investigated by NMR‐spectroscopic methods. The effect of additives such as diethylene‐glycol dimethyl ether or of 12‐crown‐4 was studied. The results were compared to those of benzyllithium compounds 4 and 6, containing a pentaoxapentadecane ansa chain. These compounds exist as contact ion pairs in which lithium is held at the anionic carbon. This is reflected in the 6Li,13C coupling and 1H,6Li‐HOESY contacts in the NMR spectra.
Tin for Organic Synthesis, 12. Synthesis of Aromatic and Olefinic Sodium Sulfonates by Electrophilic Destannylation with Trimethylsilyl Chlorosulfonate
Authors: Niestroj Michael , Lube Andreas , Neumann Wilhelm P.
Published: July 2007

A mild and effective method for the preparation of a variety of aromatic, olefinic, and acetylenic sodium sulfonates is described. The reaction of trialkylaryl‐ (2a‐k) and ‐heteroarylstannanes (4a‐d), bis‐(1‐alkenyl)dibutylstannanes (6a‐f), or trialkylalkynylsta manes with trimethylsilyl chlorosulfonate (1) followed by hydrolysis with aqueous NaHCO3 provides the sodium sulfonates in an ipso‐specific and in the case of vinylic stannanes stereospecific manner. A comparison of the reactivity of stannylated and silylated olefinic compounds 13 and 14 underlines the greater leaving ability of the stannyl moiety. The in situ preparation of the stannanes makes it possible to apply the synthetic method to natural products such as N‐substituted apocodeine (17).
Contributions to the Chemistry of Boron, 230. Electrophilic Borylation of Metallocenes: Synthesis and Molecular Structures of 1,1′,3,3′‐Tetrakis(dibromoboryl)metallocenes of the Iron Triad
Authors: Appel Andrea , Nöth Heinrich , Schmidt Martin
Published: July 2007

Reactions of metallocenes MCp2 (M = Fe, Ru, Os) with an excess of BBr3 at reflux temperature lead specifically to 1,1′,3,3′‐tetrakis(dibromoboryl)metallocenes 3, 7, and 8 in high yield. MeBBr2 and PhBBr2 are less effective borylating agents. X‐ray structural analyses of 3, 7, and 8 reveal an increasing tilt of the Br2B groups towards the metal center while retaining the trigonal‐planar environment at the boron atoms. This indicates a weak metal‐boron interaction of the kind found for carbon‐metal interactions in ferrocenyl carbocations.
Synthesis of 2‐ and 3‐Stannolenes via Addition of Trimethyltin Alkoxides to 3‐Diethylboryl‐4‐ethyl‐1,1‐dimethylstannole
Authors: Wrackmeyer Bernd , Klaus Uwe , Milius Wolfgang
Published: July 2007

Trimethyltin alkoxides (2) react stereoselectively with 3‐diethylboryl‐4‐ethyl‐1,1‐dimethylstannole (1) via addition of the Me3Sn group to C(2) to the C(2) = C(3) bond and a 1,2 shift of an ethyl group from boron to C(3) to give the 2‐stannolenes 3. The molecular structure of 3f' [R = (S)‐2‐Bu] was determined by single‐crystal X‐ray analysis, confirming the cis positions of the Et(RO)B and the Me3Sn group. These 2‐stannolenes 3 undergo, upon heating to ca. 80°C, facile rearrangement by irreversible allylic migration of the Et(RO)B group to the 3‐stannolenes 4 in which the cis positions of the boryl and the stannyl group are retained. All 2‐stannolenes (in contrast to the 3‐stannolenes) are readily deprotoborylated to give the 3‐stannolene 5. The structures of 3, 4, and 5 follow conclusively from 1H‐, 11B‐, 13C‐, and 119Sn‐NMR spectra. The negative sign of the geminal coupling constants 2J(SnSn) was determined in the case of 3, 4, and 5 by 2D 119Sn/1H heteronuclear shift correlations.
A New Synthesis of P‐Substituted 2,3‐Dihydro‐1,3‐dimethyl‐1,3,2δ3‐benzodiazaphosphorin‐4(1H)‐ones and Alkylaminodifluorophosphanes with Chlorodifluorophosphane. — Synthesis and Structure of {cis‐Bis[bis(2‐chloroethyl)aminodifluorophosphane]dichloro}platinum(II)
Authors: Plinta Hans‐Jürgen , Neda Ion , Fischer Axel , Jones Peter G. , Schmutzler Reinhard
Published: July 2007

2,3‐Dihydro‐1,3‐dimethyl‐2‐oxo‐1,3,2δ4‐benzodiazaphosphorin‐4(1H)‐one 1 reacted with diethylaminotrimethylsilane to give solely the 2‐trimethylsiloxy‐δ3‐diazaphosphorinone 2. The reaction of 2 with the 2‐chloro‐δ3‐diazaphosphorinone 3 yielded the P—O—P‐bridged compound 4 in an equilibrium reaction with elimination of trimethylchlorosilane. The synthesis of the P‐difluorophosphite‐substituted δ3‐benzodiaza‐phosphorinone 6 was effected by the reaction of chlorodifluorophosphane (5) with 1 in the presence of triethylamine in a 1:1 molar ratio, or in the reaction of 5 with 2 or 4. The reaction of 5 with 6 led, with elimination of μ‐oxo‐bis(difluoro‐phosphane), to the P(III)Cl species 3, 5 reacted with N,N'‐dimethylanthranilamide in the presence of triethylamine in a 2:1:2 molar ratio to give the N,N'‐bis(difluorophosphane) derivative 9, as evidenced by low temperature (‐30°C) 19F‐and 31P‐NMR data. At room temperature the 2‐fluoro‐δ3‐diazaphosphorinone 10 was formed from 9 with intramolecular elimination of phosphorus trifluoride. 2‐Chloroethyl‐ or bis(2‐chloroethyl)aminodifluorophosphane 11 and 12 were obtained in the reaction of 5 with 2‐chloroethyl‐ or bis(2‐chloroethyl)amine hydrochloride in the presence of triethylamine in a 1:1:2 molar ratio. 12 reacted with (COD)PtCl2 (COD = 1,5‐cyclooctadiene) in a 2:1 molar ratio to give the {cis‐bis[bis(2‐chloroethyl)aminodifluorophosphane]dichloro}platinum(II) complex 13. The characterization of 2, 4, 6, and 11–13 is based on their NMR and mass spectra. The structures of 10 and 13 were established by single‐crystal X‐ray analysis. 10 crystallizes with two independent molecules. Both six‐membered heterocycles display an envelope conformation with the phosphorus atoms 36.9 and 50.4 pm, respectively, out of the plane. The phosphorus atoms have pyramidal coordination geometry. The cis‐configuration at platinum(II) in the complex 13 was confirmed; two ligands (12) are coordinated to PtII via phosphorus. The platinum atom has a distorted square‐planar coordination geometry.
Novel Aromatic Azopolymers with Regularly Interposed Tellurium Atoms in the Backbone
Authors: Suzuki Hitomi , Nakamura Tohru , Seki Kenji
Published: July 2007

Previously unknown alt‐copoly(telluro‐1,4‐phenylene/azo‐1,4‐phenylene) and related polymers were synthesized by several different approaches, which include a) reductive polymerization of bis(4‐nitrophenyl) tellurides with zinc; b) oxidative polymerization of bis(4‐aminophenyl) telluride using a CuI/CuII redox system as catalyst under oxygen; c) electrochemical polymerization of bis(4‐amino‐3,5‐dimethylphenyl) telluride; d) condensation polymerization of 1,4‐dinitrosobenzene with bis(4‐aminophenyl) telluride Te, Te‐dichloride, and e) condensation polymerization of bis(4‐nitrophenyl) telluride with bis(4‐aminophenyl) telluride in the presence of sodium hydroxide. The polymers obtained were characterized by elemental analysis, 13C‐CPMAS NMR, IR and UV‐vis spectroscopy, GPC, and inherent viscosity measurements, and their properties were examined, particularly their electrical conductivity. The electrical conductivities of the new polymers 9b c, and 10 were shown to increase from below 10−7 up to 10−5 ∽ 10−2 S cm−1 upon bromine doping in spite of their formally interrupted conjugation structure.
Mo(CO)2(PPh3)2(O3SCF3)2: Ein neuer Vorläufer einer dikationischen, metallorganischen Lewis‐Säure mit drei freien Koordinationsstellen
Authors: Rosendorfer Philipp , Beck Wolfgang
Published: July 2007

Organometallic Lewis Acids, LIV. — Mo(CO)2(PPh3)2(O3SCF3)2: A New Precursor for an Organometallic Dicationic Lewis Acid with Three Accessible Coordination Sites

The reaction of Mo(CO)2(PPh3)2Br2 (1) with AgO3SCF3 gives the bis(triflate) complex Mo(CO)2(PPh3)2(O3SCF3)2 (3) which can be considered as a precursor for the 12‐e− system “Mo‐(CO)2(PPh3)2+2”. According to the spectroscopic data one of the two coordinated CF3SO−3 anions is acting as a chelate ligand. Treatment of 3 and of the in situ generated W(CO)2(PPh3)2(O3SCF3)2 (4) with H2O affords the dinuclear hydroxo‐bridged complexes [M2(μ‐OH)3(CO)4(PPh3)4][CF3SO3] (5: M = Mo; 6: M = W). Acetonitrile replaces the CF3SO−3 ligands in 3 and 4 to afford the cationic complexes [M(CO)2(PPh3)2(NCMe)3][CF3SO3]2 (7: M = Mo; 8: M = W). The reaction of 3 with an excess of 2‐butyne and 1‐phenyl‐1‐propyne leads to the monoalkyne complexes Mo(CO)(MeCCR)(PPh3)2(O3SCF3)2 (9: R = Me; 10: R = Ph) in moderate yield. In contrast, the bisalkyne complexes [M(CO)(MeCCMe)2(PPh3)2(O3SCF3)][CF3SO3] (11: M = Mo; 12: M = W) are formed in high yield when a CH2Cl2 solution of 2‐butyne is added to 1 and 2 in the presence of AgO3SCF3. At room temperature, 11 and 12 are highly fluxional in solution, while 9 and 10 are stereochemically rigid. Treatment of 11 with acetonitrile yields [Mo(CO)(MeCCMe)2(PPh3)2(NCMe)][CF3SO3]2 (13). Compounds 3–13 (except 4) are characterized by IR, 1H‐, 13C‐, 19F‐, and 31P‐NMR spectrescopy.
The Gas‐Phase Structure of 1‐Trifluoromethylthio‐1,2,2‐trifluoroethene, CF3SC(F)=CF2
Authors: Olleta Adriana , Haas Alois , Oberhammer Heinz
Published: July 2007

The molecular structure of 1‐trifluoromethylthio‐1,2,2‐trifluoroethene, CF3SC(F) = CF2, was determined by gas electron diffraction (GED) and ab initio calculations (HF/3–21G*). The S—CF3 bond is oriented nearly perpendicular to the ethene plane with Φ(C = C‐S‐C) = 96.9(12)°. This orientation implies that the p‐shaped sulfur lone pair is perpendicular to the ethene π orbitals. The following skeletal bond lengths (ra in Å) and angles (χ α in °) were obtained (error limits are 30 values): C = C = 1.302(19) Å, C(sp2)—S = 1.719(9) Å, SC(sp3) = 1.820(10) Å, C  CS = 120.0(9)°, and CSC  101.7(7)°. The experimental geometric parameters were reproduced reasonably well by the ab initio method.
The Molecular Structures and Conformations of Bis(dichlorosilyl)amine and Bis(dichlorosilyl)methylamine in the Gas Phase: Determination by Electron Diffraction and by ab Initio Calculations
Authors: Fleischer Holger , Hnyka Drahomir , Rankin David W. H. , Robertson Heather E. , Bühl Michael , Thiel Walter
Published: July 2007

The gas‐phase molecular structures of bis(dichlorosilyl)‐amine, (HSiCl22NH, and bis(dichlorosilyl)methylamine, (SiHCl2)2NMe, have been investigated by electron diffraction and ab initio calculations on a MP2/6–31G* level. Because the latter suggest the presence of a mixture of two conformers for each molecule, attempts were made to fit the electron diffraction data in each case by two different models, one assuming the presence of only one conformation, and another allowing for two different conformers. The principal parameters (ra) from electron diffraction for (HSiCl2)2NH are (the appropriate ab initio calculated values are given in brackets []): r(Si‐N) 171.9(2) [172.7], r(Si‐Cl) 204.1(1)[204.5] pm; Si‐N‐Si 126.5(8) [127.4] N‐Si‐Cl 107.3(5) [110.8] and Cl‐Si‐Cl 106.5(3) [107.5]°. For (SiHCl2)2NMe: r(Si‐N) 171.1(3) [171.5], r(Si‐Cl) 204.0(9) [205.2], r(N‐C) 149.7(10) [148.3] pm; Si‐N‐Si 124.9(13) [123.4], N‐Si‐Cl 109.7(5) [110.7] and Cl‐Si‐Cl 107.1(3) [107.2]° [110.8] and Cl‐Si‐Cl 106.5(3) [107.5]°. For (SiHCl2)2NMe: r(Si‐N) 171.1(3) [171.5], r(Si‐Cl) 204.0(9) [205.2], r(N‐C) 149.7(10) [148.3] pm; Si‐N‐Si 124.9(13) [123.4], N‐Si‐Cl 109.7(5) [110.7] and Cl‐Si‐Cl 107.1(3) [107.2]°. For (HSiCl2)2NH three different conformers were found to fit the experimental data with the single‐conformation model. In two of the conformers, the dichlorosilyl groups are twisted by Θ1 = 146.0(10)/Θ2 = 155.2(20)° and Θ1= 101.1(49)/Θ2 = 196.8(12)°; respectively counterclockwise from the positions in which the Si‐H bonds eclipse the N‐H bond. Both of these lead to nearly ideally staggered conformations of the two SiHCl2 groups when viewed along the Si–Si axis. In contrast, the third conformation is nearly eclipsed, with torsion angles Θ1 = 131.4(15)/Θ2 = 80.4(26)°. Planarity of the Si2NH group was assumed as suggested by ab initio calculation. For (HSiCl2)2NMe the experimental data could be suitably fitted by two conformers, in which the dichlorosilyl groups are twisted by Θ1= 161.8(13)/Θ2 = 63.1(23)° and Θ1 = 156.1(9)/ Θ2 = 177.1(15)° from the positions in which the Si‐H bonls eclipse the N‐C bond. The first of these structures has an eclipsed Si(NSi)Cl conformation and an Si…Cl nonbonded distance close to distance clse to the sum of the appropriate van der waals radii. MP2/6–31G* calculations support the GED bond lengths and bond angles of both molecules, but indicate different conformations for the most stable equilibrium geometries: the computed twists are Θ1 = 180/Θ2 = 180° and Θ1 = 177.0/ Θ2 = 183.0° for (HSiCl2)2NH and (HSiCl2)2NMe, respectively. Rotation about the Si—N bonds is a very facile process, cf. the computed [MP2/6–31G*//MP2/6–31G* + ZPE(SCF/6–31G*)] rotational barrier of 2.9 kJ. mol‐1 for (HSiCl2)2NH.
Auriophilicity in Polynuclear (Phosphane)gold(I) Thiolates {Me3CS[Au(PPh3)]2}+ BF‐4 and {(CH2S)2[Au(PPh3)]3}+ BF‐4
Authors: Sladek Alexander , Schmidbaur Hubert
Published: July 2007

The reaction of tert‐butanethiol with tris[(triphenylphosphane)gold(I)]oxonium tetrafluoroborate in dichloromethane in the presence of sodium tetrafluoroborate gave quantitative yields of a product {Me3CS[Au(PPh3)]2}+ BF‐4 (1). In the crystal lattice of this salt, the sulfonium cations are associated into dimers through close Au…Au contacts. The centrosym‐metrical tetranuclear unit has Au…Au distances of 3.292(1) and 3.206(1) Å, and the Au‐S‐Au angles are exactly 90.0(1)°. Both data are indicative of significant intra‐ and intercationic Au…Au attractions. The analogous reaction of ethane‐1, 2–dithiol afforded high yields of a product {(CH2S)2[Au(PPh3)]3}+ BF‐4 (2). The compound is fluxional in CD2Cl2 solution and shows only one 31P‐NMR signal at ‐60°C. In the crystal, the quasi C2‐symmetrical trinuclear cations feature the sulfur atoms in bridging positions between two gold atoms. The central gold atom is thus three‐coordinate; the peripheral gold atoms are two‐coordinate with Au…Au contacts at 3.284(1) and 3.129(1) Å and Au‐S‐Au angles as small as 86.5(1) and 81.0(1)°. This provides clear evidence for “auriophilic” bonding.
Metallatomsynthese, Eigenschaften und Struktur von μ2‐(η3,η3‐Toluol)bis[(η6‐toluol)eisen](Fe‐Fe)
Authors: Schneider Jöurg J. , Specht Ullrich , Goddard Richard , Krüger Carl , Ensling Jürgen , Gütlich Philipp
Published: July 2007

Metal Atom Synthesis, Properties, and Structure of μ2(η3,η3‐Toluene)bis[(η6‐toluene)iron](Fe‐Fe)

Metal atom cocondensation of iron atoms and toluene produces the mononuclear iron sandwich compound [(η6‐toluene)(η4‐toluene)Fe] 1. Complex 1 reacts with a palette of N‐containing ligands such as primary, secondary, and tertiary amines as well as pyridine, pyrrolidine, and tmeda to form highly reactive instable intermediates. In the temperature range from ‐80 to ‐30°C, the proposed intermediates react with toluene to form the first homoleptic Fe/toluene complex μ2‐(η3η3‐toluene)‐bis[(η6‐toluene)iron](Fe‐Fe) (3) regardless which N‐containing ligand is used. Additionally, 3 is also formed when ethanol is used instead of N‐containing base ligands. Black thermolabile 3 was characterized by low‐temperature 1H‐, 13C‐, and Möβbauer spectroscopy as well as by an X‐ray structure analysis (‐173°C). The X‐ray structure determination reveals a μ‐η3η3‐briding toluene ligand capping two {(η6‐toluene)Fe} units which are connected by an Fe‐Fe bond [2.746(1) Å]. However, in solution up to ‐30°C all three toluene ligands are fluxional according to 1H‐ and 13C‐NMR data. At ‐10°C 3 reacts with CO with decomposition to form Fe metal. With 2,2‐bipyridine and ethene no reaction is observed up to room temperature.
Compounds of Germanium and Tin, 16. A Tetraaryldistannene with a Long Tin—Tin Multiple Bond and Differing Environments at the Tin Atoms
Authors: Weidenbruch Manfred , Kilian Hartmut , Peters Karl , Schnering Hans Georg Von , Marsmann Heinrich
Published: July 2007

Although tetrakis(2‐tert‐butyl‐4,5,6‐trimethylphenyl)distannene (9), the first tetraaryl‐distannene to be reported on, is stable in the solid state, only the monomeric stannylene 8 can be detected in solution. An X‐ray crystal structure analysis of 9 reveals a long tin‐tin bond length of 291.0(1) pm and a trans‐bent Sn2C4 framework with different fold angles of 21.4° and 64.4°.
Synthesis and Structures of Magnesium Tetrahydridoaluminates
Authors: Nöth Heinrich , Schmidt Martin , Treit Andreas
Published: July 2007

The molecular structures of XMg(A1H4) · 4 THF (1a, 2, 3a) (X = A1H4, Cl, Br) have been determined by X‐ray structural analysis. Each compound possesses a hexacoordinated Mg center and AlH4− groups bound to this center via a single hydride bridge bond. Attempts to prepare ROMg(AlH4) compounds were successful only for sterically demanding groups R (R = CMe3, CPh3, naph, mes, smes). The 2‐naphthoxy derivative 7, a compound with the composition (naphO)Mg‐(AlH4) · 2.5 THF, is a dimer with a central Mg2O2 ring. One of its two AlH4− groups is terminally bound to one Mg atom, the other bridges the two Mg centers. This structure indicates how AlH4− transfer may occur from ROMg(AlH4) compounds to form Mg(OR)2 and Mg(AlH4)2.
Formation of a [μ‐(η1‐N:η2‐C,N)‐Aryl cyanide]biszirconocene Cation by Ligand Exchange Reaction
Authors: Röttger Dirk , Erker Gerhard , Fröhlich Roland
Published: July 2007

The planar‐tetracoordinate carbon compound 4 exchanges the bridging μ‐(η1‐C:η2‐C,C)‐2‐butyne ligand for p‐tolunitrile in dichloromethane at 90°C to yield the [μ‐(η1‐N:η2‐C,N)‐aryl cyanide]dizirconium cation complex 2a. X‐ray diffraction revealed an aza‐allenyl‐type character of the RCNZr moiety in this thermodynamically favored (μ‐nitrile)zirconium cation complex.
Chiral Carbanions, 1. Configurational Stability and Reactions of α‐Acyloxy‐Substituted α‐Methylbenzyllithium Compounds
Authors: Hammerschmidt Friedrich , Hanninger Achim
Published: July 2007

Racemic and optically active 1‐phenylethyl esters of pivalic, (—)‐camphanic and 2,4,6‐triisopropylbenzoic acid were prepared. The esters 7a of pivalic acid were deprotonated with lithium 2,2,6,6‐tetramethylpiperidide (Li‐TMP) to form α‐oxy‐α‐methylbenzyllithium compounds which are partly con‐figurationally stable prior to acylation with starting material. Camphanic ester (–)‐7b cannot be deprotonated by Li‐TMP and tBuLi is added to the ester function to afford ketone (–)‐12a. 1‐Phenylethyl 2,4,6‐triisopropylbenzoates 16 were transformed within minutes to carbanions 19 by using sBuLi/TMEDA in THF, hexane, toluene and sBuLi without TMEDA in toluene/20% diethyl ether at –78°C. The carbanions are configurationally stable only in toluene/20% diethyl ether and racemise partly in the other solvents. They react with a variety of electrophiles with either retention [MeOD, AcOD, (MeO)2CO, CICO2Me] or inversion (Me3SnCl) of configuration. Carbanions 19 rearrange on warming to –20°C to hydroxy ketone 24 with racemisation.
Reaktivität des Silaethens Ph2Si=C(SiMe3)2
Authors: Wiberg Nils , Link Matthias
Published: July 2007

Reactivity of the Silaethene Ph2Si=C(SiMe3)2

Frühere Mitteilungen: Lit.

Herrn Prof. Dr. Herbert Schumann zum 60. Geburtstag gewidmet.

Silaethene Ph2Si=C(SiMe3)2 (3), generated as a reaction intermediate by the thermal elimination of LiX from Ph2SiX‐CLi(SiMe3)2 (X = Br, F) or by the thermal cyclore‐version of the [4 + 2] cycloadduct of 3 and Ph2C=NSiMe3, forms adducts 3 donor, the stability of which increases in the order of donor = Et2O < Br− < THF < NEtMe2 < F−, and combines with the reactants a‐b (e.g. R – Li; R = H, Me, nBu, Ph) with insertion into the a‐b bond, with a=b‐c‐H [e.g. O=CtBu‐CH2‐H; CH2=CR‐CH2‐H, R = Me, CMe=CH2, CH2SiPh2CH(SiMe3)2] according to an ene reaction, with a=b (e.g. CH2=CHOMe; Ph2C=NSiMe3) or a=b=c (e.g. tBu2RSiN3, R = Me, tBu) or a=b‐c=d [e.g. CH2=CR‐CR=CH2, R/R = H/H, Me/Me, Me/CH2SiPh2CH‐(SiMe3)2; Ph2C=Y, Y = O, NSiMe3] with [2 + 2] or [3 + 2] or [4 + 2] cycloaddition. The following order of relative reactivity of trapping reagents for Ph2Si=C(SiMe3)2 was found: Ph2CO > tBu2MeSiN3 > butadiene > 2,3‐dimethylbutadiene > Ph2CNSiMe3 > tBu3SiN3 > anthracene. Summing up, it may be said that going from Me2Si=C(SiMe3)2 to Ph2Si=C‐(SiMe3)2 there is only a gradual but not principal change of silaethene reactivity. This change is due to increasing polarity and overcrowding of the double bond, that is increasing Lewis acidity and steric hindrance of the unsaturated rilicon atom. Certainly, the former silaethene stabilizes thermally by dimerization, the latter by isomerization.
Thermische Stabilisierung des Silaethens Ph2Si=C(SiMe3)2
Authors: Wiberg Nils , Link Matthias
Published: July 2007

Thermal Stabilization of the Silaethene Ph2Si=C(SiMe3)2

Frühere Mitteilungen: Lit.

Herrn Prof. Dr. Manfred Regitz zum 60. Geburtstag gewidmet.

Silaethene Ph2Si=C(SiMe3)2 (3) (generated from Ph2SiBr‐C‐Li(SiMe3)2 = 3 · LiBr in Et2O at ‐78·C) reversibly isomerizes fast by methyl migration, then a bit slower by phenyl migration, and finally fast by methyl migration into thermodynamically more stable Me2Si=C(SiMePh2)(SiMe3) (3a), then into medium stable PhMeSi=C(SiMe2Ph)(SiMe3) (3b), and finally into most stable Me2Si=C(SiMe2Ph)2 (3c) (cf. Schemes 1 and 2; Figure 1). Simultaneously with isomerization 3a · 3c [2 + 2] cycloadditions (dimerizations) of 3a and 3c occur (formation of 3a · 3a, 3a · 3c, 3c · 3c; cf. Scheme 2). Over and above that, silaethenes 3a and 3c irreversibly isomerize into disilaindanes 4a, 4b, and 4c (cf. Scheme 6). Certainly, the latter reactions are even slow at 100·C. Thermolysis of 3a · 3a, 3a · 3c, 3c · 3c at 340·C, on the other hand, leads by way of [2 + 2] cycloreversion and the intermediate formation of an equilibrium mixture of 3, 3a, 3b, 3c almost quantitatively to 4. In addition to the thermolysis products mentioned above, products of 3 and its isomers 3a, 3b, 3c with the solvents (for example Et2O; cf. Scheme 7), with the silaethene sources (for example 3 · LiBr; cf. Scheme 8), or with products formed from sources besides silaethene 3 (for example Ph2,C=N‐SiMe3;cf. Scheme 4) are observed.
[4 + 1] Cycloadditions of the Rhodium Di(methoxycarbonyl) Carbenoid to 2‐Siloxy‐1,3‐dienes
Authors: Schnaubelt Jürgen , Marks Elke , Reißig Hans‐Ulrich
Published: July 2007

The rhodium(II) acetate catalyzed reaction of dimethyl diazomalonate with 2‐siloxy‐1,3‐dienes 1a–1d and 1h furnished cyclopentene derivatives 4a–4d and 4h in moderate yields. The mechanism of this unusual [4 + 1] cycloaddition is discussed.
The Coordination of N,N‐Diethyl‐N′‐p‐tolylthiourea to Polynuclear Rhenium Carbonyl Complexes
Authors: Adams Richard D. , Huang Mingsheng , Yamamoto John H. , Zhang Lijuan
Published: July 2007

The reactions of Re2(CO)9(NCMe) and Re3(CO)10‐(CH3CN)2(μ‐H)3 with S=C(NEt2)N(H)(p‐tolyl) have yielded the new compounds Re2(CO)9[S=C(NEt2)N(H)(p‐tolyl)] (1) and Re3(CO)10(μ‐SC(NEt2)N(H)(p‐tolyl)](μ‐H)3 (2) in 89% and 98% yields, respectively. Compounds 1 and 2 were characterized by single‐crystal X‐ray diffraction analyses. Compound 1 contains an S‐coordinated S = C(NEt2)N(H)(p‐tolyl) ligand terminally coordinated in an equatorial coordination site on one of the rhenium atoms. Compound 2 contains the first example of an S‐coordinated bridging thiourea grouping. When solutions of 1 were heated to 97°C, it was transformed to the new compound {Re(CO)3[μ‐SC(N‐p‐tolyl)(NEt2)]}2 (3) plus Re2(CO)10. Compound 3 is a centro‐symmetrical dimer of the unit Re(CO)3[SC(N‐p‐tolyl)(NEt2)] in which the sulfur atom bridges the two rhenium atoms. The tolyl‐substituted nitrogen atoms are coordinated to the rhenium atoms to form two Re–S–C–N rings.
Reactions of the Alkylindium(I) Compound In4[C(SiMe3)3]4 with Sulfur and Tellurium: Syntheses of In4S4[C(SiMe3)3]4 and In4Te4[C(SiMe3)3]4 with Indium Chalcogen Heterocubane Structures
Authors: Uhl Werner , Graupner Rene , Pohlmann Michael , Pohl Siegfried , Saak Wolfgang
Published: July 2007

Tetrahedro‐Tetrakis[tris(trimethylsilyl)methyl]tetraindane(4) (1) with a tetrahedral In4 molecular center reacts with an excess of elemental sulfur or tellurium in boiling n‐hexane to give in an almost quantitative yield the appropriate In4S4 (2) or In4Te4 derivatives (3). Crystal structure determinations revealed distorted In4X4 (X = S, Te) heterocubane molecular centers for both compounds.
2,5‐Dihydro‐1,2,5‐azoniasilaboratole Derivatives – Useful Starting Materials in Heterocyclic Synthesis
Authors: Wrackmeyer Bernd , Süß Jürgen , Milius Wolfgang
Published: July 2007

1‐Alkynyl(diethylamino)dimethylsilanes [CC̊: R = Me (1a), nBu (1b), SiMe3 (1c)] react with triethylborane stereoselectively by 1,1‐ethyloboration to give the alkenes with the boryl and silyl group in cis‐positions at the C=C bond. Owing to the strongly intramolecular coordinative N‐B bond, these products are 2,5‐dihydro‐1,2,5‐azoniasilaboratoles (2a‐c). Protic reagents such as azoles (indole, pyrazole, imidazole, triazole, indazole, benzotriazole) react with 2 to give diethylamine and the respective N‐azolyl derivatives 3–8 which contain tetracoordinate boron in the case of 4–8. Compound 7, derived from indazole, was characterized by an X‐ray analysis. With ethanol, the corresponding 2,5‐dihydro‐1,2,5‐oxoniasilaboratoles 9 are obtained. Treatment of 2 with water affords 1,2,5‐oxasilaborolanes 11, presumably via an intermediate 10 with the structure of a 2,5‐dihydro‐1,2,5‐oxoniasilaboratole. All products were characterized by their 1H‐, 11B‐, 13C‐, 15N‐, and 29Si‐NMR data.
On the Effect of 1,2‐Disubstitution with Me3M (M = Si, Ge, Sn) Groups upon the Electronic Structure of 3,3‐Dimethylcyclopropene
Authors: Eckert‐Maksic Mirjana , Elbel Susanne , Stohlmeier Michael , Untiedt Sven , de Meijere Armin
Published: July 2007

He(I) PE spectra of a series of 3,3‐dimethylcyclopropenes bearing Me3Si (1), Me3Ge (2), and Me3Sn (3) groups in the 1‐ and 2‐positions, as well as the He(II) PE spectra of 1 and 3 were recorded. The changes in the lowest energy ionizations along the series are interpreted in terms of inductive and hy‐perconjugative interactions. The new compounds were prepared by reaction of lithiated 3,3‐dimethylcyclopropene with the corresponding trimethylmetal chlorides.
Preparation, Properties, and Reactions of Metal‐Containing Heterocycles, XCII. Steric and Solvent Effects of the Different Reaction Patterns of Activated Alkynes with Diphosphamanganacyclopropanes
Authors: Lindner Ekkehard , Fisahn Paul , Fawzi Riad , Steimann Manfred
Published: July 2007

The product pattern of the reaction of the alkynes ZCCZ (4–11) [Z = CO2R: R = Me (4), Et (5), nPr (6), iPr (7), nBu (8), nPent (9), neo‐Pent (10), cyc‐Hex (11)] with the diphospha‐manganacyclopropanes (1–3) depends on the polarity of the employed solvent. Whereas in n‐hexane the diphosphamanganabicyclo[3.3.0]octadienones 12a‐q, the diphosphamanganacyclopentenes 13a‐h, and the triphosphamanganabicyclo[3.2.0]heptenones 14a‐h are formed, in THF only the five‐membered heterocycles 13 occur. Compound 14d is easily oxidized to the corresponding oxide 15d. According to X‐ray structural analyses, both 14d and 15d crystallize in the space group P&1macr;. The Lewis basic properties of the phosphorus atom P2 in the heterocycle 1 were corroborated by reaction of 1 with THFCr(CO)5 leading to the adduct (16). Quantitative 31P{1H}‐NMR investigations in CDCl3 enable the determination of the product ratio 13/12 as a function of the steric encumbrance of the ester substituents. An increase of the steric hindrance leads to the preferential formation of the mo‐nocyclic compounds 13. If the steric demand at the phosphorus atom P2 is released, only the bicyclic compounds 12i‐q are formed.
Chelate‐Controlled Additions of Titanium and Lithium Enolates to Chiral β‐Formyl Esters – Diastereofacial and Simple Diastereoselectivity
Authors: Angert Hubert , Schumacher Ralf , Reißig Hans‐Ulrich
Published: July 2007

The aldol‐type additions of metal enolates 2‐Met derived from pinacolone to the chiral β‐formyl carboxylate 1a were optimized. The highest trans:cis ratio (86:14) of the products 3 was obtained when the trichlorotitanium enolate 2‐TiCl3 was combined with 1a precomplexed with one equivalent of TiCl4. The lithium enolate 2‐Li is rather unselective. The simple diastereoselectivity of prochiral enolates 4‐Met was first examined with achiral β‐formyl carboxylates 1b and 1c. Appropriate reagents made products with high anti or with high syn selectivity available when the unbranched aldehyde 1b was the electrophile. In contrast, the sterically more hindered aldehyde 1c provided syn products with all enolates 4‐Met employed. Finally, chiral aldehyde 1a was combined with prochiral enolates 4‐Met. Conditions could be found which furnished either the trans/anti or the trans/syn product 7 with good selectivity. The results are discussed and compared with reactions of related metal enolates with aldehydes capable of chelate formation.
Silanediols Derived from Silanetriols. X‐ray Crystal Structures of (2,4,6‐Me3C6H2)N(SiMe3)Si(OSiMe3)(OH)2 and (2,4,6‐Me3C6H2)N(SiMe3)Si(OSiMe2R)(OH)2 [R = CH2 (2‐NH2‐3,5‐Me2C6H2)]
Authors: Murugavel Ramaswamy , Voigt Andreas , Chandrasekhar Vadapalli , Roesky Herbert W. , Schmidt Hans‐Georg , Noltemeyer Mathias
Published: July 2007

The silanediols RN(SiMe3)Si(OSiMe3)(OH)2 (R = 2,4,6‐Me3C6H2 4, 2,6‐Me2C6H3 5, and 2,6‐iPr2C6H3 6) were prepared by the reactions of the respective silanetriols RN(SiMe3)‐Si(OH)3 1 – 3 with SiMe3Cl in THF/hexane. Silanetriol 1 in CH2Cl2/hexane solution converts over a period of 4 weeks into the silanediol (2,4,6‐Me3C6H2)N(SiMe3)Si(OSiMe2 R)‐(OH)2 [R = CH2(2‐NH2‐3,5‐Me2C6H2)] (7). Compounds 4 – 7 were characterized by means of mass, IR and NMR (1H and 29Si) spectroscopy. Additionally, the molecular structures of 4 and 7 were determined by single‐crystal X‐ray diffraction studies. Compound 4 forms O  H…O hydrogen‐bonded tetramers in the solid state. A nine‐membered ring formed by an intermolecular OH…N hydrogen bond is found in the solid‐state structure of 7.
Addition von CS2 und anderen Heteroallenen an die 16‐Elektronen‐Osmium(0)‐Komplexe trans‐[OsCl(NO)(PiPr2R)2]
Authors: Flügel Ruth , Gevert Olaf , Werner Helmut
Published: July 2007

Addition of CS2 and Other Heteroallenes to the 16‐Electron Osmium(0) Complexes trans‐[OsCl(NO)(PiPr2R)2]

The coordinatively unsaturated 16‐electron compounds trans‐[OsCl(NO)(PiPr2R)2] (1: R = iPr; 2: R = Ph) react with CS2 and COS to form the 1:1 adducts [OsCl(NO){κ2(C,S)‐SCS}(PiPr2R)2)] (3, 4) and [OsCl(NO){κ2(C,S)‐SCO}‐(PiPr2R)2] (6, 7), respectively. While compounds 3, 4 are inert toward PMe3, the Os(COS) complexes 6, 7 react with tri‐methylphosphane by abstraction of sulfur to give (OsCl(NO)‐(CO)(PiPr2R)2] (8, 9). From 1 or 2 and phenylisothiocyanate the corresponding 1:1 adducts (OsCl(NO){κ2(C,S)‐SCNPh}(PiPr2R)2] (10, 11) are obtained. Protonation and methylation reactions of 10 (R = iPr) with HBF4 or CF3SO3Me lead, by addition of the electrophile to the CN nitrogen atom, to the formation of [OsCl(NO){κ2(C,S)‐SCNHPh}‐(PiPr3)2]BF4 (12) and [OsCl(NO){κ2(C,S)‐SCN(Me)Ph}‐(PiPr3)2]CF3SO3 (13). Treatment of 1 with diphenylketene yields [OsCl(NO){κ2(C,O)‐OCCPh2}(PiPr3)2] (14). The X‐ray structure analyses of 10 and 14 confirm the coordination of phenylisothiocyanate via S and C and of diphenylketene via O and C, respectively.
Zinc complexes of the N,N,S ligand (mercaptophenyl)(picolyl)amine
Authors: Brand Udo , Vahrenkamp Heinrich
Published: July 2007

The zinc complex chemistry of the tridentate thiol ligand N‐ (2‐mercaptophenyl)(2‐picolyl)amine (MPPAH) differs considerably from that of the aliphatic analogue N‐(2‐mercaptoethyl)(2‐picolyl)amine reported previously. This is due to the lower basicity and hence bridging tendency of its aromatic thiolate function. With zinc salts of oxo anions the 1:1 complexes (MPPA)ZnX (1a–c: X = ONO2, OAc, OBz) are formed which according to spectroscopic data are monomeric while the halide (MPPA)ZnBr (2) seems to be polymeric. In the absence of coordinating anions the monomeric 2:1 complex (MPPA)2Zn (3) results which according to a crystal structure determination contains tetrahedral zinc coordinated by one MPPA ligand in a tridentate fashion while the other is only monodentate and sulfur‐bound. A similar N2S2 coordination can be deduced for the 1:1:1 complex (MPPA)Zn(STrt) (4) resulting from ZnEt2, MPPAH and triphenylmethanethiol.
Disiloxanes, Disilazanes and Related Compounds Derived from 1,8‐Disilynaphthalene
Authors: Schröck Robert , Dreihäupl Karl‐Heinz , Sladek Alexander , Angermaier Klaus , Schmidbaur Hubert
Published: July 2007

The synthesis, spectroscopic data and molecular structures of heterocycles derived from 1,8‐disilylnaphthalene are reported. The key intermediate for the preparation of the title compounds is 1,8‐bis[(trifluoromethylsulfonyl)silyl]naphthalene (3), which is prepared from 1,8‐bis[(4‐methoxyphenyl)silyl]naphthalene (2) by treatment with two equivalents of triflic acid in toluene at –20°C. The resulting silyl triflate is stable only below this temperature and was not isolated. Its reactions with water, ammonia, amines, and sulfane give the corresponding disiloxane, disilazanes and disilthiane. The molecular structure of Si,Si′‐(Naphthalene‐1,8‐diyl)‐N‐phenyldisilazane (8) was determined by X‐ray diffraction. Treatment of 2 with substoichiometric amounts of triflic acid and subsequent reaction of the resulting monosilyl triflate with tert‐butylamine gives a related chiral N‐tert‐butyl‐Si‐(4‐methoxyphenyl)disilazane 10. Its molecular structure was proven by X‐ray diffraction. A cyclic phosphonium bis(silyl)methylide (11) was synthesized by a transylidation process using 3 and CH2=P(NMe2)3. The structure of 11 was also determined by X‐ray diffraction.
Supermolecules Containing a Tetrahedral Core: A New Class of Liquid‐Crystalline Siloxanes
Authors: Mehl Georg H. , Goodby John W.
Published: July 2007

It is shown that supermolecules with a tetrahedral symmetry and appropriate side‐chains exhibit liquid‐crystalline phase behaviour. The use of an optimised hydrosylation reaction allows for the synthesis of materials that have four mesogenic groups attached to a siloxane core, where the conformation and the configuration are unambiguous. The materials show low glass transition temperatures and, depending on the spacer length, complex liquid‐crystalline morphologies.
A Synthetic and Theoretical Study of the Aggregation of Amidoaluminium Hydrides: Solid‐State Structure of the Trimethylamine Adduct [(Me3Si)2NA1(Cl)(H) · NMe3]
Authors: Gardiner Michael G. , Koutsantonis George A. , Lawrence Stacey M. , Lee Fu‐Chin , Raston Colin L.
Published: July 2007

The amidoaluminium hydride complexes [(Me3Si)2NA1(X)(H) · NMe3], X = H (1), Cl (2), were prepared by the metallation of bis(trimethylsilyl)amine by Al(X)(H)2 · NMe3 (X = H and Cl). The molecular structure of 2 as a monomeric Lewis base adduct with four‐coordinate aluminium centres and terminal amido groups was confirmed by X‐ray crystal structure determination. We also find that bis(trimethylsilyl)amine forms a thermally stable adduct of alane, (Me3Si)2N(H) · AlH3 (3). Ab initio molecular orbital calculations on the possible products arising from these reactions yielding 1 and 2 revealed that the amido‐bridged species, {(μ‐H2N)Al(X)H}2 (X = H and Cl), are favoured over nitrogen donor Lewis base adduct formation, H2NAl(X)(H) · NH3 (X = H and Cl), and then chloro‐bridged, {H2NAl(μ‐X)(H)}2, (X = Cl only), and hydrido‐bridged species, {H2NAl(X)(μ‐H)}2 (X = H and Cl).
Synthesis, Characterization and Dynamic Behavior of (π‐Allyl)palladium Complexes with Polydentate Nitrogen Ligands, Evidence of a Dissociative Mechanism
Authors: Elguero José , Fruchier Alain , De La Hoz Antonio , Jalón Félix A. , Manzano Blanca R. , Otero Antonio , Gómez‐De La Torre Felipe
Published: July 2007

New examples of the fluxional behavior of (η3‐allyl)palla‐dium complexes are described. Variable‐temperature experiments and line‐shape analysis of two (η3‐allyl)palladium complexes containing 2‐(1H‐pyrazol‐1‐yl)azine ligands were performed in order to determine the activation free energies, enthalpies and entropies of the process. A dissociative mechanism pointing to a selective Pd‐N cleavage is proposed on the basis of these results and NOE experiments above and below the coalescence temperature.
Novel Ferrocene‐Based Mono‐ and Bifunctional Tri‐1‐pyrazolylborate Ligands
Authors: Jäkle Frieder , Polborn Kurt , Wagner Matthias
Published: July 2007

The reaction of (dibromoboryl)ferrocene (1a) with pyrazole/NEt3 gave the ferrocenyltri‐1‐pyrazolylborate ligand 2. Its thallium(I) derivative 2‐Tl provides the first example of a polymeric structure with bridging tri‐1‐pyrazolylborate units in the solid state. The trinuclear iron complex 2‐Fe, which is related to 1,1′‐terferrocene, was obtained by reaction of 2 with FeCl2. The bis(polydentate) ligand 1,1′‐ferrocenediyl‐bis(tri‐1‐pyrazolylborate) (3‐Li) was prepared from 1,1′‐bis‐[bis(dimethylamino)boryl]ferrocene (1c) and a mixture of lithium pyrazolide/pyrazole in refluxing toluene/THF. 3‐Li reacts with TlNO3 to give the thallium(I) complex 3‐Tl.
Ir‐Komplexe mit P4‐Bicyclotetraphosphan und P8‐Cunean als Liganden – CO‐Insertion in eine Ir–P‐Bindung
Authors: Scheer Manfred , Becker Uta , Matern Eberhard
Published: July 2007

Ir Complexes with P4Bicyclotetraphosphane and P8Cunean as Ligands – CO Insertion into an Ir–P Bond

The reaction of [Cp*Ir(CO)2] with white phosphorus under photochemical or thermal conditions produces the bicyclotetraphosphane complexes1and2and the cunean‐type complex3. The products were characterized by NMR, IR, and mass spectroscopy as well as by X‐ray structure analyses. Complex1reacts with CO with insertion into a Ir–P bond to form2and finally [Cp*Ir(CO)2].
Hexacoordinated Group‐14 Elements with Phosphorus Donor Ligands: Syntheses and Structures of Me2E[C(PMe2)2(SiMe3)]2 (E = Si, Ge, Sn)
Authors: Karsch Hans H. , Deubelly Brigitte , Keller Ursula , Bienlein Fritz , Richter Roland , Bissinger Peter , Heckel Maximilian , Müller Gerhard
Published: July 2007

The dimethyl group‐14 element dihalides Me2EX2 (E = Si, Ge, Sn; X = Cl or Br) react with two equivalents of Li[C(P‐Me2)2(SiMe3)] to give the cis‐hexacoordinated complexes Me2E[C(PMe2)2 (SiMe3)]2 (E = Si: 2a, E = Ge: 2b, E = Sn: 2c), which were characterized spectroscopically and by means of X‐ray structure determinations. Whereas 2a and 2b are isotypic and crystallize in the space group P21/c, 2c crystallizes in the space group C2/c with crystallographic C2(2) molecular symmetry. In all cases the diphosphanylmethanide ligands bind in an unisobidentate fashion. For compound 2c, this still can be attributed to the trans influence of the methyl group, but in 2a and 2b clearly borderline cases between hexa‐ and tetracoordination are found. Compound 2b (E = Ge) is much more on the side of tetracoordination than 2a, thus underlining the importance of small polarity differences for the actual coordination number achieved in compounds with relatively unpolar bonds.
Ionic Ozonides of Lithium and Sodium: Circumventive Synthesis by Cation Exchange in Liquid Ammonia and Complexation by Cryptands
Authors: Korber Nikolaus , Jansen Martin
Published: July 2007

Concentrated solutions of the ozonides LiO3 and NaO3 in anhydrous liquid ammonia were obtained for the first time by using an ion exchange reaction that starts from CsO3. No solid LiO3 or NaO3 can be precipitated. Upon removal of the solvent, the ozonide anion oxidises ammonia, resulting in the precipitation of LiOH and NaOH, respectively. This behaviour is in sharp contrast to that of solutions of KO3, RbO3 and CsO3. Proof of the existence of LiO3 and NaO3 in the solutions is provided by complexation of the cations with cryptands, which leads to solid (Li[2.1.1])O3 and (Na[2.2.2])O3. Crystal structure analysis shows that these are ionic solids containing the V‐shaped O3− anion.
Self‐Assembly of a Triple‐Stranded meso‐Helicate from Two Iron(II) Ions and Three [CH2]3‐Bridged Bis(2,2′‐bipyridine) Ligands
Authors: Albrecht Markus , Riether Cyrill
Published: July 2007

1,3‐Bis(5′‐methyl‐2,2′‐bipyrid‐5‐yl)propane (3) can be synthesized by a two‐step procedure starting from 3‐picoline (1). In a spontaneous self‐assembly process 3 forms the binuclear triple‐stranded meso‐helicate [(3)3Fe2][PF6]4 on addition of iron(II) salts. The (Λ,Δ) structure can be shown by symmetry considerations based on NMR spectroscopy and is due to the conformational restrictions of the [CH2]3 spacer.
Syntheses of Hetero‐sila‐closo‐boranes
Authors: Wesemann Lars , Ramjoie Yves , Ganter Beate , Maisch Hartmut
Published: July 2007

Addition of 3 equivalents of KH · BEt3 to [Me3NH][Me‐SiB10H12] followed by addition of one equivalent of SnCl2 or SbI3 affords the stanna‐sila‐closo‐borate(1–) 3 and stiba‐sila‐closo‐borane 4, respectively. [MePh3P] · 3 crystallizes in the orthorhombic space group P212121.
Intramolekular stabilisierte Übergangsmetallamide: 2‐(Dimethylaminomethyl)pyrrolyl‐Komplexe des Titan(III), Vanadium(III), Chrom(III), Cobalt(II) und Nickel(II)
Authors: Drevs Helmuth , Schmeißer Annett , Hartung Helmut , Baumeister Ute
Published: July 2007

Intramolecularly Stabilized Metal Amides: 2‐(Dimethylaminomethyl)pyrrolyl Complexes of Titanium(III), Vanadium(III), Chromium(III), Cobalt(II) and Nickel(II)

By the metallation of 2‐(dimethylaminomethyl)pyrrol (HL) with butyllithium the lithium pyrrolide LiL (1) was obtained. The reactions of 1 with TiBr3 · 3 THF, VBr3 · 3 THF, CrBr3 · 3 THF, CoBr2 · 2 THF, and NiBr2 · 1.67 THF result in the formation of the 2‐(dimethylaminomethyl)pyrrolyl complexes of type ML3 (2–4), and ML2 (5, 6), respectively. The structures of these new compounds are discussed on the basis of magnetic and visible absorption measurements. An X‐ray crystal structure determination of 4 reveals a strongly distorted octahedral environment of the chromium atom with facial arrangement of the ligands.
Zirconium Species as Tools in Phosphorus Chemistry, 1 [Cp2ZrHCI]n, a Versatile Reagent
Authors: Majoral Jean‐Pierre , Zablocka Maria , Igau Alain , Cénac Nathalie
Published: July 2007

[Cp2ZrHCl]n was found to be a useful reagent for a number of either ring formation or ring opening reactions involving unsaturated phosphorus compounds. Furthermore, treatment of a variety of phosphorus derivatives with [Cp2ZrHCl]n allowed the preparation of several linear or cyclic mono‐, di‐, trior polyphosphanes as well as optically active diphosphanes.
Syntheses and Reactivity of Aminobis(diorganylamino)phosphanes
Authors: Schick Gerold , Loew Armin , Nieger Martin , Airola Karri , Niecke Edgar
Published: July 2007

Aminobis(diorganylamino)phosphanes (R2N)2PNH2 (R = iPr, c‐Hex, Ph) (2a–c), were obtained by treatment of the corresponding chlorobis(diorganylamino)phosphanes 1a–c with lithium amide in liquid ammonia. The transition metal phosphane complex (R2N)2(H2N)PNi(CO)3 (3) was prepared by reaction of 2a with tetracarbonylnickel. N‐Complexation of 2a with trimethylalane affords the iminophosphorane‐alane adduct (R2N)2HP=N(H)AlMe3 (4) by 1,2‐H shift from the nitrogen to the phosphorus atom. The corresponding reaction with aluminium trichloride leads to the formation of the salt [(R2N)2HP=N(H)]2AlC12+[AlC14]− (5), in which two iminophosphorane moieties are linked by an AlCl2 bridge. Lithiation of 2a and subsequent reaction with titanocene dichloride result in nucleophilic replacement of one chlorine atom to give the phosphanylamido‐substituted titanocene compound (R2N)2P–N(H)Ti(Cl)Cp2 (6a), which rearranges to its P‐hydroiminophosphorane tautomer (R2N)2P(H)=NTi(Cl)Cp2 (6b) on gentle heating. No isomerisation was observed in the case of N‐borylated aminophosphane (R2N)2P–NH–(9‐BBN) (7), obtained by reaction of lithiated 2a with B‐Cl‐9‐BBN. The X‐ray structure analyses of compounds 2b, c, 3, 4, 5, and 6a are discussed.
Second‐Sphere Coordination
Authors: Raymo Françisco M. , Stoddart J. Fraser
Published: July 2007

The design and synthesis of artifical receptors, able to recognize and bind transition metal complexes, is an area of growing interest in supramolecular chemistry. Macrocyclic hosts such as crown ethers, cyclodextrins, and cyclophanes have been employed to generate second‐sphere adducts with numerous transition metal complexes as a result of nonconvalent bonding interactions, such as hydrogen bonding, π‐π stacking, and hydrophobic interactions. The effect of second‐sphere coordination on the chemical, electrochemical, and photochemical properties of the adducts, as well as on their geometries in solution and in the solid state, has been investigated; these investigations have demonstrated the potential of second‐sphere coordination in modulating the behavior of transition metal complexes by designed external intervention.
Synthesis, Molecular Structure and Reactions of Stable Square‐Planar 16‐Electron Ruthenium(0) Complexes: trans‐[RuCl(NO)(PR3)2]☆
Authors: Flügel Ruth , Windmüller Bettina , Gevert Olaf , Werner Helmut
Published: July 2007

The reduction of [RuCl3(NO)(PPh3)2] (1) with Zn/Cu generates [RuCl(NO)(PPh3)2] that by ligand exchange with PR3 (R3  iPr3, iPr2Ph) affords the stable 16‐electron ruthenium (0) complexes trans‐[RuCl(NO)(PR3)2] (2, 3). The X‐ray structural analysis of 2 confirmed the square‐planar geometry around the metal center. HCl oxidatively adds to 2 and 3 to give the octahedral ruthenium(II) compounds [RuHCl2(NO)(PR3)2] (4, 5). On treatment of 2 and 3 with CO, TCNE, CH2 (generated from CH2N2) and O2, five‐coordinate 1:1 adducts [RuCl(NO)(L)(PR3)2] (6–12) are formed. The dioxygen complexes 11 and 12 react with SO2 to afford the sulfatoruthenium(II) derivatives [RuCl(NO){η2(O,O)‐O2SO2}(PR3)2] (13, 14). Compound 13 (R3  PiPr3) has been characterized by X‐ray structural analysis.
Cationic Iron Aminocarbene Complexes as Dienophiles in Diels‐Alder Reaction with Cyclopentadiene
Authors: Rück‐Braun Karola , Köuhn Jörg
Published: July 2007

The cationic iron (alkynyl)aminocarbene complexes [Cp(CO)2Fe(C(NHR)CCSiMe3][PF6], (R  C6H5,p‐CH3C6H4)1derived from aromatic amines smoothly react with cyclopentadiene in dichloromethane to yield the cycloadducts2. No reaction was observed for complexes derived from sterically demanding aliphatic amines, likeL‐alaninetert‐butyl ester. For comparison, the alkynyl‐substituted acyl iron compounds Cp(CO)2Fe(CO)CC̊ (R  SiMe3, C6H5)3were investigated, requiring TiCl4catalysis to undergo the cycloaddition reaction. The structures of the cycloadducts4were determined by X‐ray crystallography.