bluuebunny/crossref_metadata_2025 huggingface dataset:
Diimidokomplexe [M(NR)2(PMe3)2(L)] des vierwertigen Molybdäns und Wolframs: Struktur, Moleküldynamik und Aktivierung π‐acider Liganden
Authors: Radius Udo , Sundermeyer Jörg , Pritzkow Hans
Published: July 2007

Highervalent Derivatives of the d‐Metal Acids, 14[1]. — Diimido Complexes [M(NR)2(PMe3)2(L)] of Tetravalent Molybedenum and Tungsten: Structure, Molecular Dynamics, and Activation of π‐Acidic Ligands

[M(NMes)2Cl2(dme)] (M = Mo 1, W 2; Mes = mesityl) or the trans‐phosphane complexes [M(NMes)2(PMe3)2Cl2] (3, 4) are reduced by C8K in the presence of PMe3 to give diamagnetic d2 complexes [Mo(NMes)2(PMe3}3] (5) and [W(NMes)2‐(PMe3)3] (6). At least one PMe3 ligand in 5 and 6 is readily substituted by more π‐acidic substrates such as ethene, ethyne, 2‐butyne, and P(OEt)3. The reaction with ethene leads to [Mo(NMes)2(η2‐C2H4)(PMe3)2] (7) and [W(NMes)2‐(η2‐C2H4)(PMe3)2] (8). Furthermore, pentacoordinate complexes [Mo(NMes)2(η2‐C2Me2)(PMe3)2] (9), [W(NMes)2(η2‐C2H2)(PMe3)2] (10), and [W(NMes)2(PMe3){P(OEt)3)2] (11) have been synthesized from 5 or 6. The X‐ray structure analysis of 8 reveals a trigonal‐bipyramidal geometry about tungsten with both arylimido groups perfectly lying in the equatorial mirror plane. The ethene ligand is occupying the third equatorial position. The C2 vector is oriented perpendicular to the WN2 plane. Dynamic NMR studies are consistent with a tbp geometry being also present in solution at the low‐temperature limit. At higher temperatures a rapid exchange of the PMe3 ligands with noncoordinated phosphane according to a dissociative mechanism is observed.
The molecular and solid‐state structure of borazine has been determined at 115 and 160 K by single‐crystal X‐ray crystallography. The molecular structure has C2 symmetry with small deviations from the expected D3h symmetry. The mean value of the BN bond length is 1.429(1) A and the interbond angles of the six‐membered ring are 117.1(1)° at the boron atoms and 122.9(1)° at the nitrogen atoms (mean values). Similar to benzene an unambiguous assignment of the molecular symmetry is not possible. — The crystal packing is not comparable to any known phase of benzene, and surprisingly the molecules are not stacked having coplanar rings. Instead, the molecules are found in tilted layers. No significant intermolecular interaction could be detected. The generated difference electron density maps show the typical distribution pattern for polar bonds.
Authors: Boese Roland , Maulitz Andreas H. , Stellberg Peter
Published: July 2007

Borazin im festen Zustand: Verdient es, als “anorganisches Benzol” bezeichnet zu werden?
Reactions and Structure of Electron‐Precise Triborane(5) and Tetraborane(6) Derivatives
Authors: Linti Gerald , Loderer Dirk , Nöth Heinrich , Polborn Kurt , Rattay Wilfried
Published: July 2007

An improved synthesis of B3(NMe2)5 (2), B4(NMe2)6 (1), and B6(NMe2)8 (4) is reported. From each compound two of the four terminal dimethylamino groups are readily replaced by halogen atoms yielding α,ω‐dihalides Bn(NMe2)nX2 (n = 3, 4; X = Cl, Br, I). These are used in turn to replace the substitu‐ent X by groups like RO, RS, RHN, R2P, and R. Crystal structure determinations on several of these compounds reveal as a common feature planar (C2N)BB2 and (C2N)B(B)X groups which are arranged in an approximately orthogonal manner to one‐another with NBBN dihedral angles ranging from 69 to 104.6°. Consequently, there is no significant π bonding between the boron atoms.
Reactions of Monomeric Phosphanylboranes with Acyl Chlorides: 1‐Oxa‐3‐oxonia‐5‐phospha‐2‐borata‐3,5‐cyclohexadienes
Authors: Nöth Heinrich , Staude Siegfried , Thomann Martina , Kroner Jürgen , Paine Robert T.
Published: July 2007

Monomeric B‐[bis(trimethylsilyl)phosphanyl]‐9‐borabicyclo‐[3.3.1]nonane (1) reacts with acyl chlorides 2 in a 1:2 ratio to afford deep red derivatives of six‐membered oxaoxonia‐s̀2,λD3‐phosphaboratacyclohexadienes 3. In contrast, the (di‐tert‐butylboryloxy)phosphaethene 5 is obtained from tBu2BP‐(SiMe3)2 (4) and PhC(O)Cl. It is assumed that both reactions proceed via a common intermediate, an (acylphosphanyl)bo‐rane 6. The color of compounds 3, which feature a flat boat conformation, is due to a π−π* transition.
Thianthren‐Radikalkation‐Tetrachloroaluminat
Authors: Bock Hans , Rauschenbach Andreas , Näther Christian , Kleine Markus , Havlas Zdenek
Published: July 2007

Structures and Molecular Properties of Charge‐Perturbed Molecules, 53[1,2]. — Thianthrene Radical Cation Tetrachloroaluminate

One‐electron oxidation of thianthrene, which exhibits a reversible half‐wave potential at + 1.3 V and an irreversible one at + 1.65 V, under aprotic conditions with AlCl3/H2CCl2 yields the violet radical cation salt [H4C6S2C6H4⊕][AlCl4⊖]. Its single‐crystal structure analysis at 90 K reveals an interplanar angle between the phenyl rings of 174° and demonstrates that the neutral sulfur heterocyclic molecule, bent by 128°, is considerably flattened upon one‐electron removal. Semiempirical enthalpy of formation hypersurfaces allow to rationalize the experimental results by a double‐minimum potential for the bent neutral molecule with a rather low inversion barrier and a single minimum one for a planar radical cation. Other radical cation properties such as the spin distribution deduced from its ESR spectrum or the visible absorption maxima near \documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \nu $\end{document} = 11000 and at 18250 cm‐1 corresponding to π → π* and π → σ* transitions are also satisfactorily reproduced by PM3 calculations partly including configuration interaction based on the experimental structure.
Metalloragnische Verbindungen der Lanthanoide, 90[1] [(tert‐Butylcyclopentadienyl)dimethyl(tetramethylcyclopentadienyl)silan]‐Komplexe von Lanthan, Neodym und Lutetium
Authors: Schumann Herbert , Glanz Mario , Hemling Holger
Published: July 2007

Organometallic Compounds of the Lanthanides, 90[1]. ‐ [(tert‐Butylcyclopentadienyl)dimethyl‐(tetramethylcyclopentadienyl)silane] Complexes of Lanthanum, Neodymium, and Lutetium

[(tBuC5H3)SiMe2(C5Me4)]Li2 (1) reacts with LnCl3 (Ln = La, Lu) in THF to yield [(tBuC5H3)SiMe2(C5Me4)]Ln(μ‐Cl)2Li‐(OEt2)2 [Ln = La (3a), Lu (3c)]. The reactions of LnCl3 (Ln = La, Nd) with [(tBuC5H3)SiMe2(C5Me4)]Na2 (2) and (C5Me4H)Na in THF result in the formation of the chiral tris(cyclopentadienyl) complexes [(tBuC5H3)SiMe2(C5Me4)]Ln‐(C5Me4H)(THF) [Ln = La (4a), Nd (4b)]. The 1H‐ and 13CNMR and mass spectra of the new compounds as well as the X‐ray crystal structure of 4a are discussed.
The supramolecular structures of complex tri[gold(I)]sulfonium cations
Authors: Angermaier Klaus , Schmidbaur Hubert
Published: July 2007

Tris[(trimethylphosphane)gold(I)]sulfonium tetrafluoroborate (1) has been prepared from the corresponding oxonium salt [(Me3P)Au]3O+ BF‐4 and bis(trimethylsilyl) sulfide, (Me3Si)2S. The analogous triisopropylphosphane and methyldiphenylphosphane complexes (2, 3) have been obtained in a similar way. The products are stable crystalline solids, the structure of which has been determined by X‐ray methods. They are composed of independent tetrafluoroborate anions and pyramidal tri(gold)sulfonium cations, which are aggregated to form dimeric units (as in 3) or even strings of dimers (as in 1). It is only in complex 2 that steric effects, originating from the bulky phosphane ligands, prevent the building of supra‐molecular (supracationic) aggregates. In the independent pyramidal cations of 2 only short intracationic Au…Au contacts have been detected. These are complemented by intercationic gold‐gold contacts of similar length in the structures of 1 and 3. ‐ In the preparation of complex 1, the species [(Me3P)Au]4S2+ (BF‐4)2 (4) with hypercoordinate sulfur atoms has also been detected by mass spectroscopy.
Komplexierung von 1,4‐Dihydro‐1,4‐diborafulvenen mit Ni(cod)‐ und Pt(cod)‐Fragmenten
Authors: Gangnus Bernd , Feßenbecker Achim , Pritzkow Hans , Siebert Walter
Published: July 2007

Complexation of 1,4‐Dihydro‐1,4‐diborafulvenes with Ni(cod) and Pt(cod) Fragments*

Reactions of the 1,4‐diborapentafulvene derivatives 1 and 2a, b with M(cod)2 (M = Ni, Pt) yield the complexes [(η5‐1)Ni‐(cod)] (8), [(μ,η2η5‐2a){Ni(cod)}2] (9a), [(μ,η2,η5‐2b){Ni(cod)}2] (9b), and [(μ,η2,η5‐2a){Pt(cod)}2] (10). Compounds 9 and 10 are the first examples of complexes with 2a, b as a μ,η2,η5‐ligand. The X‐ray structure analyses of 9b and 10 are described.
A Comparative Study of the Reactivity of Mn(no)2L2H and Mn(CO)3L2H Complexes (L = Phosphorus Donor)
Authors: Nietlispach Daniel , Bosch Henry William , Berke Heinz
Published: July 2007

Mn(NO)2L2H complexes [L = PMe3 1a, PEt3 1b, P(OMe)3 1c, P(OEt)3 1d, P(OiPr)3 1e] have been prepared by the reaction of the corresponding Mn(NO)2L2Br compounds with NaBH4 in ethanol. The reactivity of 1a and 1b is compared to that of Mn(CO)3L2H species (L = PMe3 2a, L = PEt3 2b). Compound 1b reacts with weak acids like PhOH, (CF3)2CHOH and CH3COOH to yield Mn(NO)2(PEt3)2X complexes [X = OPh 3a, OCH(CF3)2 3b, OC(O)CH3 3c] and H2. Compound 2b does not undergo reaction with these acids. At room temperature in toluene 1a, b undergo facile CO2 insertion processes, while 2a, b do not show this reactivity even under more rigorous reaction conditions. From 1a, b and CO2 formato complexes Mn(NO)2L2[OC(O)H] (L = PMe3 4a, L = PEt3 4c) are obtained. The reaction of 1b with salicylaldehyde in toluene proceeds with the formation of a [2‐(hydroxymethyl)‐phenoxy]dinitrosylbis(triethylphosphane) manganese complex 5b, which exchanges the phenoxy ligand in the presence of excess of salicylaldehyde to give (2‐formylphenoxy)‐dinitrosylbis(triethylphosphane)manganese (6b) and α,2‐dihydroxytoluene. p‐Hydroxybenzaldehyde, vanilline, and 4‐hydroxy‐3,5‐dimethoxybenzaldehyde and 1b also afford phenoxy derivatives Mn(NO)2(PEt3)2(OAr) [Ar = p‐OC6H4‐CHO 7a; OC6H3‐2‐OCH3‐4‐CHO 7b; OC6H2‐2,6‐(OCH3)2‐4‐CHO 7c] and H2. Compounds 2a, b do not react with any of these hydroxybenzaldehydes. Compounds 1a, b have been converted into Mn(NO)2L2 [(Z)‐C(COOR′)C(R)H] species (L = PMe3, R = H, R′ = Me 8a; L = PEt3, R = H, R′ = Me 8b; L = PMe3 R, R′ = Me 9a; L = PMe3, R = Ph, R′ = Et 10a; L = PMe3, R = COOMe, R′ = Me 11a; L = PEt3, R = COOMe, R′ = Me 11b) in the presence of alkyl propiolates RC≡CCOOMe (R = H, Me, Ph, COOMe; R′ = Me, Et). Similarly, but under more rigorous conditions, insertion of RC≡CCOOMe (R = H, COOMe) into 2a, b occurs and α metalation products Mn(CO)3(PMe3)2[(Z)‐C(COOMe) = CHR] (L = PMe3, R = H 12a; L = PEt3, R = H 12b; L = PMe3, R = COOMe 13a; L = PEt3, R = COOMe 13b) are formed. In the case of the methyl propiolate insertion into 2a, 10% of an additional β‐metalation compound Mn(CO)3(PMe3)2[(Z)‐CH = CH(COOMe)] (12c) have been detected spectroscopically. Compounds 11b and 13a, b have been transformed into manganacyclic complexes MN[C(COOMe)CH(COOMe)]‐(NO)2(PEt3)2 (14b) and MN[C(COOMe)CH(COOMe)]‐(CO)2L2 (L = PMe3 15a; L = PEt3, CO 15b; L = PEt3 15c). Compound 15c has been identified spectroscopically, and 1a, 8a, and 9a have been characterized by X‐ray structure determinations.
One‐Electron Oxidation of Aryltriazenes to Radical Cations
Authors: Dunsch Lothar , Gollas Bernhard , Neudeck Andreas , Petr Andreas , Speiser Bernd , Stahl Hartmut
Published: July 2007

3,3‐Dimethyl‐1‐(4‐R‐phenyl)‐ [R = (CH3)2N, C2H5O, CH3O, CH3; 3] and 3‐Methyl‐1‐(4‐R1‐phenyl)‐3‐(4‐R2‐phenyl)triazenes [R1 = (CH3)2N, CH3O, NO2, R2 = CH3O, H, 4] are oxidized electrochemically and chemically to their one‐electron oxidation products. Cyclic voltammograms of the triazenes are discussed, and ESR as well as UV/Vis spectra of the radical cations are presented. The stability of the triazene radical cations generated depends on the substituents on the aryl rings. 4‐R‐Benzenediazonium ions are identified as one of the decay products of the radical cations by means of cyclic voltammetry and UV/Vis spectroelectrochemistry.
Organic Syntheses via Transition Metal Complexes, 74[1] Novel Phosphonium Allenide and 2‐Phosphanylethenyl Carbene Chromium and Tungsten Complexes
Authors: Aumann Rudolf , Jasper Beate , Läge Mechtild , Krebs Bernt
Published: July 2007

Alkynylcarbene complexes (CO)5MC(OEt)‐C≡CR 1 (M = Cr, W; R = Ph, tBu, SiMe3) readily add tertiary phosphanes PPhR2′ 4 (R′ = Ph, Me) to form stable zwitterionic phosphonium allenide complexes (CO)5M‐‐C(OEt) = CC(R)‐P+PhR2′ 5. Complex 5a (M = Cr, R = R′ = Ph) was characterized by X‐ray diffraction. The addition of secondary phosphanes PHR2 6 to 1 affords red (2‐phosphanyl ethenyl)‐carbene complexes (CO)5MC(OEt)‐CHC(R)‐PR2 (E)‐8 (R = tBu, cC6H11, Ph) in 34–89% isolated yields. Dinuclear complexes (CO)5MC(OEt)‐CHC(R)‐P(R2)M(CO)5 (E)‐9 are obtained as byproducts. Compounds (E)‐8b (M = Cr, R = cC6H11) and (E)‐9i (M = Cr, R = Ph) were characterized by X‐ray analyses.
Synthesis and Complexation of a New 14‐Membered N2O2 Macrocycle with vic‐Dioxime Moieties
Authors: Hamuryudan Esin , Bekaroǧlu ÖZer
Published: July 2007

The new vic‐dioxime ligand 2 (LH4) carrying a 14‐membered N2O2 macrocycle has been prepared. Mononuclear complex (LH3)2Ni, trinuclear complexes (LH)2Cu3, (LH)2Co3, (LH)2‐Pd3, and (LH)2Co3(py)3Cl3, dinuclear complex (LH3)2‐(UO2)2(OH)2, and pentanuclear complex [L2Cu5(phen)2]‐(NO3)2 have been synthesized from LH4. The electrochemical properties of tri‐ and pentanuclear complexes were investigated by cyclic voltammetry. For (LH)2Cu3 two reduction waves appeared at 0.215 and ‐0.870 V. [L2Cu5(phen)2](NO3)2 exhibited four reduction waves at 0.200, ‐0.025, ‐0.670, and ‐1.170 V.
Derivatives of Aza‐nido‐tetraborane and Diaza‐arachno‐pentaborane from Tri‐tert‐butylazadiboriridine
Authors: Müller Matthias , Wagner Trixie , Englert Ulli , Paetzold Peter
Published: July 2007

The Lewis acids RBH2 are added to the basis B‐B bond of tri‐tert‐butylazadiboriridine, NB2tBu3 (1a), to give 5‐alkyl‐1,2,3‐tri‐tert‐butyl‐1‐aza‐nido‐tetraboranes of type 3 (two endo‐H atoms at B5) or type 4 (one H atom in a B2–B5 bridging position, one exo‐H atom at B5), either as a mixture of 3 and 4 (3, 4b–d: R  Me, tBu, CMe2iPr) or with the isomer 4 in high excess (4e, f: R  Ph, sBu). The reaction of dialkylboranes R2BH with 1a yields 5,5‐dialkyl‐1,2,3‐tri‐tert‐butyl‐1‐aza‐nido‐tetraboranes of type 4 (one H atom in a B2‐B5 bridging position; 4g, h: R2  Et2, cycloocta‐1,5‐diyl). In boiling THF, trialkylboranes BR3 transform 1a into NB2tBu2R which, expectedly, dimerizes spontaneously to give a dialkyltetra‐tert‐butyl‐2,5‐diaza‐nido‐hexaborane of type 2 (2a, b: R  Me, Et). The products of the addition of aminoboranes H2BNRR' to 1a are identified as alkyl derivatives of 2,5‐diaza‐arachno‐pentaborane, N2B3tH2tBu3RR' (5a–d, R/R' = H/Pr, H/tBu, Me/Me, Et/Et). The aminoborane H2B  NiPr2 with a sterically more demanding amino group hydroborates the B‐B bond of 1a to give the acyclic product iPr2NBH‐B(tBu)‐N(tBu)B(tBu)H (6). In contrast to the B atoms, the N atoms in the electron‐deficient cluster skeletons of 2–5 need not take part in (3c,2e) bonds of the s̀ type. The molecular structures of 4c, 5d, and 6 are confirmed by X‐ray structural analyses.
New Pathways in Tellurium‐Chalkogen‐Nitrogen Chemistry: Preparations, Structures, and Properties of Telluraheterocycles
Authors: Haas Alois , Pryka Michael
Published: July 2007

Treatment of Se(NSO)2 with TeF4 in CH2Cl2 yields the compounds (4a) and (5b), while with TeBr4 after six months (2d) is formed. An almost quantitative yield of Cl4Te2N4S2 (6) is obtained from either Cl6Te2N2S (1a) and (CH3)3SiNSNSi(CH3)3 in CH2Cl2 at 20°C (2 d) or TeCl4 and (CH3)3SiNSO (molar ratio 1:2) in CH2Cl2 at 60°C (3 d). The use of (CH3)3SiOSi(CH3)3 as solvent in the last mentioned procedure gives 1a and small amounts of Cl2Te(NSO)2. Similarly, F2Te(NSO)2 is prepared from TeF4 and (CH3)3SiNSO in CH2Cl2. Dechlorination of 1a with (C6H5)3Sb leads to (2a), which is also produced from TeCl4 and [(CH3)3Si]2NSN[Si(CH3)3]2. When TeF4 is used instead of TeCl4 (molar ratio 3:1) the salt (7a) is formed. Similarly, (7b) is prepared from 2a and AsF5 or Ag+[AsF−6] in SO2. A new method for the preparation of bicyclic type 1 telluraheterocycles involves bromination of 2a yielding Cl2Br4Te2N2S (1b). Dehalogenation with (C6H5)3Sb converts 1b into (2b). When 2b is treated with Br2 in CH2Cl2 an oxidative halogenation takes place with formation of Br6Te2N2S (1c). Metathetical exchange between 2b and Ag+[AsF−6] gives (7c). Isostructural S(NSO)2 reacts with TeCl4 for several weeks at 60°C in CH2Cl2 to form S4N4. TeCl4 and [S5N+5][Te3Cl−3], in contrast to the corresponding reaction with Se(NSO)2. The molecular structures of 4a, 7b, 8, and [S5N+5][Te3Cl−13] have been determined by X‐ray diffraction methods. Spectroscopic data for all new compounds are presented.
Tellurium Polycations by Oxidation of Tellurium with Tungsten Halides Syntheses and Crystal Structures of Te6(WOCl4)2 and Te6I2(WCl6)2
Authors: Beck Johannes
Published: July 2007

WOCl4 reacts at 200°C with tellurium in a sealed, evacuated ampoule with the formation of Te6(WOCl4)2. The structure consists of six‐membered tellurium rings in a boat conformation with significant transannular interactions and of pyramidal WOCl4 units which are linked by linear asymmetric O...;WO bridges to polymeric (WOCl4)n, chains. The observed paramagnetism is consistent with the ionic formulation Te2+6[(WOCl−4)2]n. In the reaction of WCl6, I2 and Te in a 2:1:6 ratio Te6I2(WCl6)2 is formed at 150°C. The crystal structure consists of Te6I2+2cations and of slightly distorted octahedral WCl−6 anions. The Te6I2+2 ions are isostructural with Se6I2+2 and consist of a six‐membered ring of Te atoms in the chair conformation with two I atoms bound in the 1,4‐positions.
The Structures of [X2YNYX2]+ Cations (X  F, Cl; Y  S, Se). A Comparison of X‐ray and ab Initio Studies[1]
Authors: Schulz Axel , Broschag Matthias , Tornieporth‐Oetting Inis C. , Klapötke Thomas M. , Buzek Peter , Schleyer Paul Von Ragué , White Peter S.
Published: July 2007

The structures of cationic species of the series [X2YNYX2]+ (X  F, Cl; Y  S, Se) have been computed ab initio using all electron treatments for first‐row elements and sulfur and quasi‐relativistic pseudopotentials for Se and Cl. Splitvalence basis sets with polarization and diffuse functions were employed. The MP2 results for the (non‐isostructural!) cations [Cl2SeNSeCl2]+ (1: Cs) and [F2SNSF2]+ (2: C2v) are in excellent agreement with the experimental (X‐ray) observations. Both structures represent local minima. A deeper minimum for either of the cations is represented by another C2v isomer which for crystal lattice energy reasons is stable in the isolated state only. The geometries of the hitherto unknown species [Cl2SNSCl2]+ (3) and [F2SeNSeF2]+ (4) have been assessed by ab initio HF calculations. In analogy to 2, cations 3 and 4 are predicted to prefer C2v symmetry. Therefore, 1 exhibits unusual structural features. According to strictly localized natural bond orbital analysis (NBO), the central nitrogen atoms in 1 and 2 possess two lone pairs of electrons (LP: one sp hybrid and one p orbital). The relatively short SeN and SN bond distances in 1 (1.741–1.760 Å) and 2 (1.551 Å) can best be attributed to LP(N)→s̀*(YX) negative hyperconjugation (1: Y  Se, X  Cl; 2: Y  S, X  F).
Übertragung eines cyclo‐E5‐Liganden (E  P, As) von einem Eisen‐ auf ein Ruthenium‐ und ein Osmium‐Zentrum
Authors: Rink Barbara , Scherer Otto J. , Wolmershäuser Gotthelf
Published: July 2007

Transfer of a cyclo‐E5 Ligand (E  P, As) from an Iron to a Ruthenium and an Osmium Center☆

The thermolysis of [Cp*Fe(η5‐E5)] (1) and [{Cp*M(CO)2}2] (2, 3) affords by cyclo‐E5 transfer the sandwich complexes [Cp* M(η5‐E5)] (4a, b: M  Ru, E  P, As; 4c: M  Os, E  P). The crystal‐structure analysis of [(C5Me4Et)Os(η5‐P5)] (4c') confirms its sandwich‐type structure.
Selective Activation of Aromatic C—H Bonds with Lithium Atoms at 77 K
Authors: Tacke Matthias
Published: July 2007

In the presence of donor bases like THF lithium atoms are able to activate benzene derivatives under cryogenic reaction conditions. Only ring‐metalated products and solid lithium hydride are formed selectively. The thermodynamically favored product benzyllithium or biphenyl generated by dimerization of free phenyl radicals are not found. This is one of the very few examples of metal atoms undergoing a C—H activation without further photoexcitation.
Zerfall von Nitrosylazid, N4O: Existieren auch cyclische Stickstoff‐Oxide?
Authors: Klapötke Thomas M. , Schulz Axel
Published: July 2007

Decomposition of Nitrosyl Azide, N4O: Are Cyclic Nitrogen Oxides Existent?

The unimolecular decomposition of nitrosyl azide (tetranitrogen monoxide), N4O, was studied at the electron‐correlated, spin‐restricted RMP2 level with the 6–31G(d,p) and 6–31+G* basis sets. Frequency calculations were performed at 6–31+G* on the optimized structures. It is demonstrated that the experimentally established trans‐trans‐N4O (Cs) may either interconvert into cis‐cis‐N4O which upon decomposition forms cyclic N4O (C2v) as an intermediate species to finally give N2O (C∞v) and N2, or trans‐trans‐N4O may directly dissociate into cyclic N2O (C2v) and N2. All structures determined were rationalized by energy hypersurface calculations.
Photocatalytic Oxygenation of Selected Cycloalkenes in Aqueous Solutions Induced by Water‐Soluble Metal Porphyrin Complexes
Authors: Hennig Horst , Behling Jördis , Meusinger Reinhard , Weber Lutz
Published: July 2007

Water‐soluble manganese(III) as well as iron(III) porphyrinates are introduced as light‐sensitive precursor compounds for the photocatalytic activation of dioxygen in aqueous solutions. It is shown that in the presence of α‐pinene (4) and the further cycloalkenes 11–13 photocatalytic oxygenation reactions occur. The dependence of the selectivity of the oxygen transfer to the olefin on both the presence of water and the variation of the substrate‐to‐catalyst ratio is discussed. The catalyst may be conveniently separated from the substrates/products by using aqueous solvent systems.
Enantioselektive Katalyse, XI. Darstellung von optisch reinen Diphosphanen mit vier Stereozentren
Authors: Nagel Ulrich , Krink Thomas
Published: July 2007

Enantioselective Catalysis, XI. – Preparation of Optically Pure Diphosphanes with Four Stereogenic Centers

We synthesized a number of new diphosphanes with four stereogenic centers and two different aryl groups on each phosphorus atom. Starting with the diastereomeric mixture of [P(R,S),3R,4R,P′(R,S)]‐1‐(tert‐butoxycarbonyl)‐bis(phenyl‐phosphanyl)pyrrolidine (1a,b,c) we prepared the corresponding chlorophosphanes by use of chlorotrimethylsilane followed by treatment with hexachloroethane. The chlorophosphanes react with Grignard. or organolithio compounds to the target molecules. For the chromatographic separation and purification of the diastereomers we transformed them into their Pdl2 complexes (Pd‐4a,b,c to Pd‐12a,b,c). The structures of Pd‐4a, Pd‐4c, Pd‐6c, Pd‐8b and Pd‐9a were determined by X‐ray diffraction analysis. A correlation between structural parameters of these Pd complexes and the enantio‐selection for rhodium complexes of the same ligands as hydrogenation catalysts is suggested.
(C5H5)Co‐Induced Head‐Head Coupling of Dimethylfulvene: Formation, Molecular Structure and Electrochemistry of (1,1,2,2‐Tetramethyl‐1,2‐ethanediyl)bis(cobaltocene)
Authors: Wadepohl Hubert , Lieth Claus‐Wilhelm Von Der , Paffen Franz‐Josef , Pritzkow Hans
Published: July 2007

Head‐head coupling of a dimethylfulvene ligand occures in the reaction of 6,6‐dimethylpentafulvene (1a) with [(C5H5)Co(C2H4)2] (7) to give (1,1,2,2‐tetramethyl‐1,2‐ethanediyl)bis(cobaltocene) (8a). In contrast, the mononuclear η4‐fulvene complexes 3b, c are obtained from 6‐ethyl‐6‐methyl‐(1b) and 6,6‐diethylfulvene (1c) and 7. The crystal structures of 8a and the corresponding bis(ferrocene) 9a have been determined. The electrochemical behaviour of 8a and 9a shows 8a+, 8a−, and 9a+ to be localised mixed‐valence species. Molecular mechanics calculations have been performed on the title complex and related derivatives.
Ylidyl‐dihalogenphosphane – Strukturbilder einer sich anbahnenden Dissoziation
Authors: Schmidpeter Alfred , Nöth Heinrich , Jochem Georg , Schrödel Hans‐Peter , Karaghiosoff Konstantin
Published: July 2007

Ylidyl‐dihalophosphanes Provide Structural Snapshots on Their Way to Dissociation

The reaction of phosphonium ylides with phosphorus trihalides has been studied for the synthesis of ylidyl‐dihalophos‐phanes (= dihalophosphanyl ylides) Ph3PCRPX2 3, X = Cl, and 9, X = Br. Compounds 3, R = aryl, are readily prepared from the phosphonium bromides [Ph3PCH2R]Br, compounds 3, R = alkyl, SiMe3 or PCl2, and 9 are obtained from silylylides Ph3PCRSiMe3, compound 3, R = PPh3+ results from the addition of PCl3 to the hexaphenylcarbodiphosphorane. A (β‐morpholinovinyl)dichlorophosphane 12 has also been prepared. Ylides 3 are oxidized by sulfur and selenium and are converted to ylidyl‐chlorophosphenium (= chloro‐phosphaalkenyl‐phosphonium) salts [Ph3PCRPCl]AlCl4 10. In the 31P‐NMR spectra of 3 and 9 the geminal coupling 2JPP indicates the phosphorus lone pair to be synperiplanar to the phosphonio group. In one case the P(III)C rotation barrier has been estimated from VT‐31P‐NMR spectra. By X‐ray crystallography the structures of 3, R = Me, 2,6‐Cl2C6H4, 4‐NO2C6H5, PCl2, of 9, R = Me (two molecules), SiMe3, of an ylidyl‐selenophosphonyl dichloride (11b), and of 12 have been analyzed. They provide representatives for the full range of rotation from the symmetric conformer with two equal PX bonds to the conformer with one PX bond perpendicular to the PCP plane and with this bond being extremely elongated. Thus, they map out the pathway to PX bond breaking. On this way the initial charge transfer from the ylidic carbon to the antibonding PX orbital ends up in a π donation and PX dissociation.
Mono‐ und Diferriophosphane und ‐thioxophosphorane
Authors: Lorenz Ingo‐Peter , Mürschel Petra , Pohl Wolfgang , Polborn Kurt
Published: July 2007

Mono‐ and Diferriophosphanes and ‐thioxophosphoranes

Herrn Professor Dr. Ekkehard Lindner zum 60. Geburtstag gewidmet.

The substitution of organic substituents in phosphanes or thioxophosphoranes by the 17‐electron fragments CpFe‐(CO)2 (Fp) leads to isolobal ferriophosphanes or ‐thioxophosphoranes. The mono‐ and diferriophosphanes FpnPPh3−n [n = 1 (3), 2 (4)] are obtained by deprotonation of the mono‐ and diferriophosphonium salts [FpnPPh3−nH]X [n = 1 (1), 2 (2)] with DBU. They are oxidized by sulfur giving the mono‐ and diferriothioxophosphoranes FpnPPh3−n(S) [n = 1 (5), 2 (6)]. Sulfide 5 arises also from the reaction of CpFe(CO)2Cl and Ph2PH(S)/DBU. The one‐sided decarbonylation reaction of 6 leads to FpFp′PPh(S) (7, Fp′ = CpFeCO). The Fp substituents (17 electrons) in 3–7 coordinate as one‐electron donors to the PhnP‐ or PhnP(S) units (n = 1, 2). The bridging functions in 4 and 6 are hitherto unknown. The molecular structures of the complexes 5–7 were determined by X‐ray structure analyses.
Chiral Ligands for Transition Metal Complexation
Authors: Crisci Gerardo , Hahm Torsten , Weaver George W. , Winterfeldt Ekkehard
Published: July 2007

Novel chiral salen‐ or salphen‐type ligands with stereogenic centres in the 1,3‐dicarbonyl moiety 2 as well as in the amino bridge in 15–18 were synthesized from the enantiomerically pure Hajos‐Wiechert ketone.
Structure and Conformation of Bis(trifluoromethylthio)methane, CH2(SCF3)2
Authors: Korn Monika , Haas Alois , Oberhammer Heinz
Published: July 2007

The geometric structure and conformational properties of bis(trifluoromethylthio)methane, CH2(SCF3)2' were determined by gas electron diffraction. The main conformer (70 ± 15%) possesses C2 symmetry with dihedral angles Φ(SCSC) = 79.1(10)°. The second conformer possesses C1 symmetry. The following skeletal geometric parameters (distances ra [pm] and angles 〈α[°] with 3‐σ uncertainties) were obtained: CS 183.6(3), SCF3, 179.3(3), SCS 112.1(6), and CSC 98.2(10). The geometric structures and relative conformational stabilities were well reproduced by ab initio calculations at the HF/3‐21G* level.
Reactions of Phosphaalkenes with Hexafluoroacetone
Authors: Müller Christian , Bartsch Rainer , Fischer Axel , Jones Peter G. , Schmutzler Reinhard
Published: July 2007

The dimethylamino‐substituted phosphaalkene 1 reacts with hexafluoroacetone (HFA) with addition at the PC bond to form the 1,5,2‐dioxaphosphorinane 2. The structure of 2 was confirmed by an X‐ray crystal structure analysis. The six‐membered ring displays an envelope conformation with the phosphorus atom out of the plane, but the phosphorus is disordered over two sites. Reaction of P‐trimethylsilyl‐substituted phosphaalkenes with HFA proceeds with retention of the PC double bond and insertion of HFA into the PSi bond. Two isomeric products are obtained and are characterized by 1H‐, 13C‐, 19F‐, and 31P‐NMR spectroscopy, IR spectroscopy, mass spectrometry, and elemental analysis.
Photochemische Reaktionen von Übergangsmetall‐Organyl‐Komplexen mit Olefinen, 13Photochemisch induzierte [5+2],homo[5+21‐Cycloaddition von 3‐Hexin an Tricarbonyl(η5‐2,4‐cycloheptadien‐l‐yl)mangan
Authors: Kreiter Cornelius G. , Fiedler Christian , Frank Walter , Reiß Guido J.
Published: July 2007

Photochemical Reactions of Transition Metal Organyl Complexes with Olefins, 13

12. Mitteilung: Lit.

. – Photochemically Induced [5+2],
homo
[5+2] Cycloaddition of 3‐Hexyne to Tricarbonyl(η
5
‐2,4‐cycloheptadien‐1‐yl)manganese

Tricarbonyl(η5‐2,4‐cycloheptadien‐1‐yl)manganese (1) reacts upon UV irradiation in hexane at 243 K with two equivalents of 3‐hexyne (2) in successive [5+2],homo[5+2] cycloadditions to give tricarbonyl(η2:2:1‐1,2,3,11‐tetraethyltricyclo‐[5.3.1.04,10]undeca‐2,5‐dien‐11‐yl)manganese (3). Its crystal and molecular structure was determined by an X‐ray diffraction analysis, in solution it was studied also by IR and NMR spectroscopy.
Pentamethylcyclopentadienyl Iridium Complexes Containing Chalcogenido Ligands: Reactions of Cp*Ir(CO)2 with Elemental Sulfur and Selenium
Authors: Herberhold Max , Jin Guo‐Xin , Milius Wolfgang
Published: July 2007

Photolysis or thermolysis of Cp*Ir(CO)2 (1) in the presence of excess sulfur (S8) gives Cp*Ir(CO)(S4) (2a) which is further decarbonylated to [Cp*Ir(μ‐S4)]2 (4a). The analogous reaction of 1 with excess selenium leads to Cp*2Ir2(μ‐Se)(μ‐Se4) (6b). In the case of limited chalcogen supply, the products are [Cp*Ir(CO)(μ‐E)]2 [E = S (3a), Se 3b)] and [Cp*Ir(μ‐E)]4 [E = S (5a), Se (5b)]. A stepwise formation of the pseudocubane clusters 5a,b from dinuclear precursors is assumed. The solid‐state structure of 2a has been determined by X‐ray crystallography.
Reactions at Silicon‐Silicon Bonds, V. Selective Trichlorosilylation of Alkyl(diorganylamino)chlorophosphanes with Hexachlorodisilane or with Trichlorosilane/Triethylamine. ‐ Two Routes to New Functional Trichlorosilylphosphanes
Authors: Müller Lutz‐Peter , Mont Wolf‐Walther Du , Jeske Jörg , Jones Peter G.
Published: July 2007

The reaction of alkyl(diorganylamino)chlorophosphanes R(R2′N)PCl 1 (1a: R = tBu, R′ = Et, 1b: R = iPr, R′ = iPr; 1c: R = iPr, R′ = Ph) with hexachlorodisilane, afforded alkyl(diorganylamino)trichlorosilylphosphanes R(R2′N)PSiCl3 2 (2a: R = tBu, R′ = Et; 2b: R = iPr, R′ = iPr; 2c: R = iPr, R′ = Ph) and silicon tetrachloride. An intermediate formed in the reaction of 1b with hexachlorodisilane, the adduct iPr(iPr2N)(Cl)P‐Si(Cl)3‐SiCl3 (3b = 1b · Si2Cl6), was detected by 31P‐ and 29Si‐NMR spectra that indicate pentacoordinated silicon bound to tetracoordinated phosphorus and tetracoordinated silicon. Trichlorosilylphosphanes 2 are also available from 1 under very mild conditions by reductive trichlorosilylation with trichlorosilane in the presence of triethylamine. Compounds 2 were identified analytically, by mass spectroscopy, multinuclear NMR, and an X‐ray structure determination of 2c.
Darstellung von phosphorhaltigen Heterocyclen aus 2‐Aminonicotinsäure
Authors: Sonnenburg Ralf , Neda Ion , Fischer Axel , Jones Peter G. , Schmutzler Reinhard
Published: July 2007

Synthesis of Phosphorus‐Containing Heterocycles from 2‐Aminonicotinic Acid

The reaction of 2‐aminonicotinic acid with ethyl chloroformate, followed by alkylation with NaH/Mel and decarboxylation with methylamine, led to N‐methyl‐2‐(methylamino)nicotinamide (3). Treatment of 3 with PCl3 in the presence of triethylamine gave the phosphorinanone 4. Substitution of chlorine in 4 by the dimethylamino‐, N,N,N′‐trimethylethylenediamino‐, or bis(2‐chloroethyl)amino group furnished 5–7. Hydrolysis of 4 with small amounts of water formed the phosphoryl derivative 8 as the hydrochloride. The spirophosphoranes 9 and 10 were produced by reaction of 5 with hexafluoroacetone and tetrachloro‐o‐benzoquinone, respectively. In order to evaluate its coordination ability, the N,N,N′‐trimethylethylenediamino‐substituted diazaphosphorinanone 6 was allowed to react with the tetracarbonyl norbornadiene derivatives of chromium(0) and molybdenum(0). The cis‐substituted tetracarbonyl complexes 12 and 13 were formed. In the reaction of 7 with dichloro(1,5‐cyclooctadiene)platinum(II) the cis‐disubstituted complex 15 was formed. A comparison of benzo‐ and pyrido‐annulated phosphorinanones was made, and their differences were discussed. In the case of the compounds 2, 7, and 9 singlecrystal X‐ray structure analyes were performed. In 9 the heterocycle C and N atoms are coplanar (the phosphorus lies 60 pm outside the plane); P and N(2) are displaced in 7 to the same side of the plane of the remaining four atoms.
Ligandgesteuerte P2‐Verknüpfung zu einem acyclischen P4‐Liganden
Authors: Scherer Otto J. , Berg Gerald , Wolmershäuser Gotthelf
Published: July 2007

Ligand‐Induced P2 Coupling to an Acyclic P4 Ligand

The further terminal coordination of M(CO)5 (M = Cr, Mo W) to [(Cp‴Co)2(μ‐η2:2‐P2)2] (1), Cp‴ = 1,2,4‐tBu3C5H2, affords the polynuclear cobalt complexes [(Cp‴Co)2(μ3(4)‐η4:4:1:(1)‐P4){M(CO)5}n], n = 1; M = Cr (2a), Mo (2b), W (2c) and n = 2, M = W (3). The X‐ray crystal structure analyses as well as low‐temperature 31P‐NMR studies show that in 1 the two P2 ligands are rectangularly oriented while in 2b, 2c, and 3 they are coupled to an acyclic, trapezoidally arranged P4 chain.
A Deceiving X‐ray Single‐Crystal Structure Determination: Amino‐Hydrogen Exchange in Amino‐alkynylboranes and ab initio Investigations of Alkynylboranes, Borirenes, and Boraallenes
Authors: Metzler Nils , Nöth Heinrich
Published: July 2007

Dimeric(dimethylamino)(phenylethynyl)borane (2)2 is formed by the reaction of bis(dimethylamino)(phenylethynyl)‐borane (1) with 9‐BBN‐H. An X‐ray single‐crystal diffraction study revealed a central B2N2 four‐membered ring for (2)2 with both alkynyl groups pointing to the same side in a cisoid arrangement. However, solution and solid‐state NMR as well as ab initio calculations on model compounds show that the cis arrangement in the crystal chosen for X‐ray diffraction is not representative of the bulk material, which consists of both cis and trans isomers. Further investigations of the competition between hydrogen‐amino group exchange and hydroboration in the reaction of amino‐alkynylboranes with hydroborating agents (9‐BBN‐H and catB‐H) show the exchange to be much faster even in the presence of Wilkinson's catalyst and with cyclic amino‐alkynylboranes such as 1,3‐dimethyl‐2‐[(trimethylsily1)ethynyl]‐1,3,2‐diazaborolidine (3). Ab initio calculations on alkynylboranes I, borirenes II, and boraallenes III, which are all geometrical isomers, show alkynylboranes to be the most stable isomers only if strongly π‐donating groups X (X = NH2, F) are attached to the boron atom. In any case, boraallenes are highest in energy.
Silylimido and Disilylamido Groups as Clustering Centers for (Phosphane)gold(I) Units: Aurated Silylammonium Cations
Authors: Angermaier Klaus , Schmidbaur Hubert
Published: July 2007

The reaction of hexamethyldisilazane with tris[(phosphane)‐aurio(I)]oxonium tetrafluoroborates affords the corresponding trinuclear μ3‐trimethylsilylimido compounds of the type {[(R3P)Au]3NSiMe3}+ BF−4 (1a‐f). With (triphenylsilyl)amine and the oxonium reagents the analogous series of Ph3Si derivatives (2a‐f) is formed (R = Me, Et, iPr; R3 = Ph2Me; R = Ph, o‐Tol). The Et3P‐based oxonium salt and (Me3Si)2NH give the dinuclear μ‐trimethylsilylamido complex {[(Et3P)Au]2N(SiMe3)2)2}+ BF−4 (3) as the main product. The crystal and molecular structures of complexes 2a, 2e, and 3 were determined. The trinuclear cations have a pseudo‐tetrahedral structure with small Au‐N‐Au angles and short Au‐Au distances for the SiNAu3 units. The Ph3SiN units in 2a and 2e are capping triangles of gold atoms, while in the cation of 3 the (Me3Si)2N unit is bridging a pair of gold atoms. In the 31P‐ and 14N‐NMR spectra of compounds 1 and 2 (except for 1f and 21) the coupling J(31P,14N) is observed. This coupling is temperature‐dependent, owing to changes in the relaxation characteristics in solution at low temperature. The decomposition of compounds 1 and 2 leads to the formation of pentanudear dications {[(R3P)Au]5N}2+ for R = Me, Ph.
Chiral Organometallic Reagents, XVI. Enantiomerization of α‐Thio‐, α‐Seleno‐, and α‐Telluro‐Substituted Alkyllithium Compounds; Kinetic and Mechanistic Studies
Authors: Hoffmann Reinhard W. , Dress Ruprecht K. , Ruhland Thomas , Wenzel Andreas
Published: July 2007

The rate of enantiomerization of the racemic α‐phenylselenoalkyllithium compound 6 has been determined by dynamic NMR spectroscopy in [D8]THF. The enantiomerization rate was found to be first order with respect to monomeric 6 and to show no conspicuous solvent dependence (diethyl ether; toluene + 1 eq. of THF) or change upon addition of LiClO4. The marked steric effects on the enantiomerization rate found with the α‐duryl‐ and α‐mesityl‐selenoalkyllithium compounds 7c and 7d suggest that rotation about the carbanion‐selenium bond may be the rate‐determining step in those sterically hindered systems. Similar steric effects were detected for the enantiomerization of the corresponding α‐arylthio‐ and α‐aryltelluroalkyllithium compounds 7j and 7f, but are absent with the α‐arylsilyl‐substituted alkyllithium compound 7o. This finding, along with the fact that the phenyltelluro‐ (7e), phenylseleno‐ (6), and phenylthio‐alkyllithium compounds (7g) have essentially the same enantiomerization barrier, lead us to propose that in these cases a reorganization within the contact ion pair is the rate limiting step for the enantiomerization.
Bis(cyclopentadienyl)methane‐Bridged Dinuclear Complexes, 10 The Bis(cyclopentadienyl)methane Link between Lewis Basic and Lewis Acidic Metal Centers
Authors: Stempfle Bernd , Schmidt Simone , Sundermeyer Jörg , Werner Helmut
Published: July 2007

The mononuclear rhodium complexes [(C5H5CH2C5H4)‐Rh(CO)2] (1) and [(C5H5CH2C5H4)Rh(PhCCPh)(PiPr3)] (2) readily react with nBuLi or TlOEt to yield the corresponding lithium salts 3 and 4 or thallium salts 5 and 6. The reaction of these salts with [(C5H5)Nb(NtBu)Cl2] (7) leads to the formation of the heterodinuclear compounds [{CH2(C5H4)2}‐{Rh(CO)2}{(C5H5)Nb(NtBu)Cl}] (8) and [{CH2(C5H4)2}‐{Rh(PhCCPh)(PiPr3)}{(C5H5)Nb(NtBu)Cl}] (9), respectively. Treatment of 3–6 with [Mo(NtBu)2Cl2] (10) gives the heterodinuclear Rh/Mo complexes [{CH2(C5H4)2}{Rh(CO)2}‐{Mo(NtBu)2Cl}] (11) and [{CH2(C5H4)2}{Rh(PhCCPh)‐(PiPr3)}{Mo(NtBu)2Cl}] (12). The analogous reaction of [Mo(NMes)2Cl2(DME)] (13) with 3–6 yields the corresponding complexes [{CH2(C5H4)2}{Rh(CO)2}{Mo(NMes)2Cl}] (14) and [{CH2(C5H4)2}{Rh(PhCCPh)(PiPr3)}{Mo(NMes)2Cl}] (15). From the monometallated ligand [(C5H5CH2C5H4)M] (M = Li: 16; M = Tl: 17) and the imidometal compounds 7, 10 and 13, the mononuclear complexes [(C5H5CH2C5H4)(C5H5)Nb‐(NtBu)Cl] (18) and [(C5H5CH2C5H4)Mo(NR)2Cl] (R = tBu: 19; R = Mes: 20) have been obtained.
Synthesis and Properties of (Tetra‐tert‐butylphthalocyaninato)ruthenium(II) and (Tetra‐tert‐butyl‐2,3‐naphthalocyaninato)ruthenium(II)
Authors: Hanack Michael , Knecht Siegfried , Polley Rainer
Published: July 2007

The first synthesis of pure tert‐butyl‐substituted (phthalocyaninato)‐ and (2,3‐naphthalocyaninato)ruthenium [(tBu)4‐MacRu] by thermal decomposition of (tBu)4MacRu(L)2 (L = 3‐chloropyridine, ammonia) is described. The compounds were characterized by UV/Vis, IR, and NMR measurements.
The First Titanacyclic Five‐Membered Cumulene. Synthesis, Structure, and Reactivity
Authors: Burlakov Vladimir V. , Ohff Andreas , Lefeber Claudia , Tillack Annegret , Baumann Wolfgang , Kempe Rhett , Rosenthal Uwe
Published: July 2007

The first five‐membered titanacyclic cumulene (5) was prepared by treatment of the titanocene generator Cp2Ti(Me3SiC2SiMe3) with the di‐tert‐butylbutadiyne in a molecular one‐to‐one ratio. The reaction of 5 with “Cp2Zr” or of the analogous complex with “Cp2Ti” leads to cleavage of the central C‐C bond in the metallacyclocumulene complexes to afford the same product, the heterodimetallic ρ, π,‐alkynyl‐bridged titanocene‐zirconocene complex Cp2Zr(μ‐η1η2‐C≡CtBu)Cp2Ti(μ‐η1η2‐C≡CtBu) (6), in which each alkynyl group is π‐bonded to one and π‐bonded to the other metal as shown by X‐ray diffraction studies. In solution the two alkynyl groups become equivalent. The coupling reaction of “Cp2Ti” with bis(trimethylsilyl)butadiyne in a one‐to‐two molecular ratio leads to the unsymmetrically substituted titanacyclopentadiene (7).
Preparation, Properties, and Reactions of Metal‐Containing Heterocycles, XCI. Insertion of Activated Alkynes and Sulfur into the P‐P Bond of Diphosphamolybdacyclopropanes
Authors: Lindner Ekkehard , Kneißle Wilfried , Fawzi Riad , Steimann Manfred , Mayer Hermann A. , Gierling Karlheinz
Published: July 2007

The insertion of the alkynes ZC≡CZ (2a‐i) [Z = Co2R: R = Me (a), Et (b), nPr (c), iPr (d), nBu (e), tBu (f), neo‐Pent (g), cyc‐Hex (h); Z = CF3 (i)] into the P1‐P2 bond of the diphos‐phamolybdacyclopropane Mes (1) (Mes = 2,4,6‐trimethylphenyl) results in the formation of the diphosphamolybdacyclopentenes Mes (3a‐i). According to an X‐ray structural analysis, 3a crystallizes in the space group P21/c with the mesityl function at P2 and the cyclopentadienyl fragment at the metal atom on the opposite side of the planar five‐membered ring. The same orientation is found in solution by NMR experiments (NOE; 2D 1H, 13C HETCOR). Kinetic investigations confirm that the rate constants decrease in the sequence R = Me > Et > nPr > isoProp > Cy > nBu > neo‐Pent > tBu. The second‐order reaction and the strongly negative activation entropy which was determined in the case of the reaction 1 + 2e → 3e are consistent with a nucleophilic attack of P2 at one of the triply bonded carbon atoms of the alkyne. The reaction of 3a, h with sulfur affords the diastereomeric compounds Mes (4a, h). An X‐ray structural analysis of the heterocycle 4h, which crystallizes in the space group P1, shows the presence of the enantiomeric pair SR/RS. The reaction of 1 with alkynes is hindered if this heterocycle is oxidized by sulfur to give Mes (5). Further reaction of 5 with sulfur leads to the ring‐expanded heterocyclic intermediate (6) which crystallizes in the space group P1. The five‐membered ring in 6 has an envelope conformation. Upon thermally induced cleavage of the P2S2Mes fragment from 6 the three‐membered ring (7) is formed as the final product.
Reactions of Complex Ligands, LXVI. Diastereomerically Pure 2‐Ethynylcyclopropanecarboxylic Acid Derivatives and (2‐Ethynylcyclopropyl)methoxycarbene Complexes of Chromium and Tungsten
Authors: Kretschik Oliver , Nieger Martin , Dötz Karl Heinz
Published: July 2007

Ethynylcyclopropanecarboxylic acid esters 2c/2t were prepared from phenylbutenyne 1 and ethyl diazoacetate. Pure diastereomers were obtained by chromatography and converted into the corresponding acyl chlorides 4c/4t. Reaction with K2[M(CO)5] (M = Cr, W) affords alkynylcyclopropylcarbene complexes of chromium 7c/7t and tungsten 8c/8t. An X‐ray structure analysis of 7t reveals a distorted cyclopropane skeleton.
Polare Iminoborane: Reaktionen des (tert‐Butylimino)(pentafluorphenyl)borans
Authors: Klöfkorn Christiane , Schmidt Martin , Spaniol Thomas , Wagner Trixie , Costisor Otilia , Paetzold Peter
Published: July 2007

Polar Iminoboranes: Reactions of (tert‐Butylimino)(pentafluorophenyl)borane

The reactions of the iminoborane C6F5‐B≡N‐tBu (1) with nitriles and isonitriles are studied. Nitriles RCN give cycloadducts either of the triazadiboracyclohexane type (3a; R = iPr) or of the tetrazatriborabicyclo[4.2.0]octane type [4b‐d; R = Ph, p‐C6H4Me, p‐C6H4(CF3)] or of the (iminomethyl)borazine type (5e, f; R = Me, Et). Isonitriles RNC yield mainly adducts of RNC to a cycloaddition product of the diazadiboracyclopentane type (6a, b; R = 2,6‐C6H3Me2, tBu); the adduct of RNC to a diazadiboracyclobutane may be a side‐product (7b; R = tBu). The iminoborane Me3Si(tBu)N‐B=NtBu reacts with two molecules of (2,6‐C6H3Me2)NC to give the corresponding azaboracyclobutane 8. The iminoborane tBu‐B≡N‐C6F5 (1′), formed by gas‐phase elimination of ClSiMe3 from Cl(tBu)B = N(C6F5)SiMe3 (9), cyclodimerizes more readily than the isomeric borane 1. The cyclodimer 2′ gives 1:1‐addition reactions with tBuNC, PMe3, and MeNC, respectively; the added components fluctuate in solutions of the products 7b'‐d'. A similar fluctuation is observed with the 1:1 adduct 7c from PMe3 and the cyclodimer 2 of the iminoborane 1. The products 3a, 5e, 6a, 8 crystallize in the space groups P21/c, P21/n, Pbca, and P21/c, respectively.
The Reaction of RLi Species with CO and Isonitriles: IR Spectroscopic Investigations in Liquid Xenon and Ab‐Initio Calculations of the Intermediates
Authors: Tacke Matthias
Published: July 2007

Solutions of alkyl‐ or aryllithium compounds were treated with CO or tBu‐NC in liquid xenon (LXe) at low temperature. Carbonyllithium compounds, acyllithium and the corresponding isolobal isonitrile products were characterized by IR spectroscopy for the first time. The structures, energies and characteristic IR frequencies of the intermediates were calculated by using ab‐initio methods and discussed with the experimental values.
Addition von Hydrofullerid [C60H]− an koordinierte, ungesättigte Kohlenwasserstoffe: Bindung von Fulleren an Metallkomplexe über Kohlenwasserstoffbrücken
Authors: Beck Wolfgang , Bentele Hanns‐Jörg , Hüffer Stephan
Published: July 2007

Addition of Hydrofulleride [C60H]− to Coordinated, Unsaturated Hydrocarbons: Binding of Fullerene to Metal Complexes through Hydrocarbon Bridges

Herrn Professor Herbert Walter Roesky zum 60. Geburtstag gewidmet.

Hydrofulleride [C60H]− is added to the hydrocarbon ligands of the cationic complexes [(OC)5Re(η2‐C2H4)]+, [(OC)3Mn‐(η6‐C6H6)]+, [(OC)3M(η5‐C6H7)]+ (M = Fe, Ru), [(OC)3Fe(η5‐C7H9)]+, and [(η5‐C5H5)Fe(η6‐C5H4CH2)]+.
LiClO4‐Promoted Addition of Alkyl Grignard and Alkynyllithium Reagents to Ketones. Comparison of a 5 M LiClO4/Diethyl Ether Solution with CeCl3
Authors: Ipaktschi Junes , Eckert Thomas
Published: July 2007

The influence of a 5 M ethereal LiClO4 solution as solvent on the addition of different alkyl Grignard and alkynyllithium reagents to highly enolizable ketones was studied. A comparison with the results in the presence of CeCl3 shows a similar improvement in the yield.