bluuebunny/crossref_metadata_2025 huggingface dataset:
Ylidylphosphorsulfide, ‐selenide, ‐disulfide, ‐sulfidselenide und ‐diselenide
Authors: Jochem Georg , Karaghiosoff Konstantin , Plank Stefan , Schmidpeter Stefan Dick Und Alfred
Published: July 2007

Ylidylphosphorus Sulfides, Selenides, Disulfides, Sulfide Selenides, and Diselenides

We report on the first stable monomeric phosphorus mono‐chalcogenides 2, 8 and the first stable dichalcogenides 4, 10 without bulky or intramolecularly coordinating substituents. They are stabilized by a high contribution of the zwitterionic resonance formula, which follows both from the NMR spectra and from an X‐ray structure determination. Their preparation starts from triphenylphosphoniumylidyl‐dichlorophosphanes 1. For the monochalcogenides they are treated with sodium sulfide or selenide or better with bis(trimethylsilyl) sulfide or selenide. In case of the C‐phenyl and C‐meta‐tolyl representatives and also of the C‐trimethylsilyl compound a number of secondary, partly novel products are obtained. – The dichalcogenides result from the reaction with sodium disulfide and diselenide, respectively, or from the oxidation of the monochalcogenides. – Alkylation of the monochalcogenides results in ylidylalkylchalcogenophosphenium salts 13, 15. In solution they are in equilibrium with more or less of the covalent form 14, 16, depending on the anion and on the solvent. Alkylation is often accompanied by secondary reactions. A diselenide loses selenium on alkylation.
Stabilization of a Planar‐tetracoordinate Carbon Center in an Organometallic Complex Containing Both a Zirconocene and a Hafnocene Moiety
Authors: Röttger Dirk , Erker Gerhard , Fröhlich Roland , Kotila Sirpa
Published: July 2007

The methylhafnocene cation 2a reacts with bispropynylzirco‐nocene to give a single regioisomeric planar‐tetracoordinate carbon compound (4a) that contains the hafnium atom singly‐bonded and the zirconium center η2‐coordinated to the bridging μ‐(η1‐C:η2‐C,C‐2‐butyne) ligand. However, the reaction between the methylzirconocene cation 2b with bis(phenylacetylide)hafnocene (3b) gives the pure regioiso‐mer 4b with an opposite relative arrangement of the two group 4 transition metals (the methyl is at the planar‐tetra‐coordinate carbon atom C2). Complex 4a was characterized by an X‐ray crystal structure analysis.
Triferriothioxophosphoranes: First Structural Characterization of a μ3‐P=S Complex
Authors: Lorenz Ingo‐Peter , Pohl Wolfgang , Polborn Kurt
Published: July 2007

The P‐H‐functional triferriophosphonium salts [{CpFe‐(CO)2}3PH]2FeCl4 (1) and [{μ‐CO(CpFeCO)2}{CpFe‐(CO)2}PH]2FeCl4 (4) are easily deprotonated by DBU to the corresponding unstable triferriophosphanes 2, 5, which subsequently are oxidized by sulfur to the triferriophosphane sulfides {CpFe(CO)2}3P=S (3) and {μ‐CO(CpFeCO)2}{CpFe‐(CO)2}P=S (6), respectively. The photolysis of 3 results only in its decomposition by elimination of [CpFe(CO)2]2, whereas the photolysis of 6 cleaves off one CO ligand to give the new spiro compound (CpFeCO)(μ‐η2‐PS){μ‐CO(CpFeCO)2} (7), where the P=S unit is η2‐bonded to the 15‐electron CpFeCO fragment, and the phosphorus atom bridges two 17‐electron fragments. Compound 7 shows a new coordination mode of the PS unit where sulfur is also bound to one of the metal atoms. Compounds 6 and 7 can be regarded as first examples of a new class of PS complexes of transition metals. All compounds were characterized by IR, 31P{1H}‐ and 13C{1H}‐NMR spectroscopy as well as mass spectrometry; for 6 the X‐ray analytical data are given.
2‐(2,4‐Di‐tert‐butylphenyl)‐1,1‐bis(trimethylsilyl)silene and 2‐(2,4,6‐Tri‐tert‐butylphenyl)‐1,1‐bis(trimethylsilyl)silene – Two New Sterically Protected but Still Unstable Silaethenes
Authors: Luderer Frank , Reinke Helmut , Oehme Hartmut
Published: July 2007

(2,4‐Di‐tert‐butylphenyl)tris(trimethylsilyl)silylmethanol (1a), prepared by the reaction of tris(trimethylsilyl)silylmagnesium bromide with 2,4‐di‐tert‐butylbenzaldehyde, was deproto‐nated by treatment with methyllithium in ether at –78°C to give the transient 2‐(2,4‐di‐tert‐butylphenyl)‐1,1‐bis(trimeth‐ylsilyl)silene (3a), which dimerizes in a head‐to‐head fashion with the formation of (E)‐/(Z)‐3,4‐bis(2,4‐di‐tert‐butylphenyl)‐1,1,2,2‐tetrakis(trimethylsilyl)‐1,2‐disilacyclobutane (5). Besides 5 an unstable compound 4 was obtained, which was preliminarly assigned as 5,7‐di‐tert‐butyl‐1‐(2,4‐di‐tert‐bu‐tylphenyl) ‐1,2,3,8a‐tetrahydro‐2,2,3,3‐tetrakis(trimeth‐ylsilyl)‐1,2‐disilanaphthalene (4), the formal [2 + 4] cyclodimer of 3a. Compound 4 gradually decomposes to give (E)‐/(Z)‐5, and is considered to be the kinetically preferred dimer of 3a, which is converted into the thermodynamically stable 5. 2,4,6‐Tri‐tert‐butylbenzaldehyde reacts with tris(tri‐methylsilyl)silyllithium resulting in the formation of 6,8‐di‐tert‐butyl‐1,2,3,4‐tetrahydro‐4,4‐dimethyl‐2,2‐ bis(trimethylsilyl)‐2‐silanaphthalene (6). Compound 6 is the product of the insertion of the Si=C bond into the C–H bond of an o‐tert‐butyl group of the intermediate 2‐(2,4,6‐tri‐tert‐butylphenyl)‐1,1‐bis(trimethylsilyl)silene (3b), which despite extreme steric shielding proved to be still unstable. For compounds (Z)‐5 and 6 the results of the X‐ray analyses are given.
Syntheses and Structures of 13‐Substituted 1,5,9‐Triazatricyclo[7.3.1.05,13]‐tridecanes and Their Copper(II) Chloride Complexes
Authors: Köhn Randolf D. , Seifert Guido , Kociok‐Köhn Gabriele
Published: July 2007

The orthoamides2a, b(R = Ph and PhCH2) have been prepared by alkylation of the guanidinium salt4+BPh4−with PhNa and PhCH2Na, respectively. The crystal structures of the two orthoamides have been determined by X‐ray crystallography. Their reaction with CuCl2gives 1:1 complexes. The crystal structure of the complex with2ashows a square planar geometry around the copper atom with η2‐2aand two chlorides and weak interactions two the third nitrogen atom and a C–H bond of2ain the axial positions.
Charge‐Transfer Complexes of Metal Dithiolenes, XXII. Bis(maleonitriledithiolato)oxomolybdate(IV) – Bipyridinium Ion Pairs
Authors: Götz Brigitte , Knoch Falk , Kisch Horst
Published: July 2007

The oxomolybdenum complex (NBu4)2[MoO(mnt)2] (mnt2− = maleonitriledithiolate) 2 was characterized by X‐ray structural analysis. By metathetic reaction with bipyridinium salts AX2 ion pair charge‐transfer complexes of composition {A2+[MoO(mnt)2]2−} were isolated. Although a plot of the energy of the ion pair charge‐transfer band vs. the driving force of electron transfer from the dianion to the dication afforded a straight line, the slope of 0.45 suggests significant deviations from the Hush‐Marcus model. When bis(2‐hy‐droxyethyl)viologen is the acceptor, in addition to the supra‐molecular charge‐transfer interaction, hydrogen bridges are introduced between the two components as indicated by IR and X‐ray diffraction analysis.
Coordination Chemistry of Dimethylgold Halides with Bidentate Phosphorus and Arsenic Ligands – Revisited
Authors: Paul Martin , Schmidbaur Hubert
Published: July 2007

Dimethylgold(III) chloride and bromide, (Me2AuX)2, react with bis(diphenylphosphanyl)methane (dppm, molar ratio 1:2) to give the P‐monohapto complexes cis‐Me2AuX(dppm) (1a, b) in quantitative yields. The products are readily oxidized by air to yield the P‐hapto P′‐monoxides 2a, b. Treatment of 1a, b with AgNO3 affords an ionic nitrate [Me2Au(dppm)]2 [NO3−]2 (1c), which contains a dinuclear cation. A mixed bromide/nitrate (from 1b and half the equivalent amount of AgNO3) is thermally unstable and undergoes elimination of ethane to give an ionic tetranuclear gold(I) complex [(dppm)4Au4Br2]2+ [NO3−]2 (3b). – Treatment of (Me2AuCl)2 with CH2(AsPh2)2 (dpam, molar ratio 1:2) gives cis‐Me2‐AuCl(dpam) (1d), the arsenic analog of 1a, which is not sensitive to oxygen. – The reaction of bis(diphenylphosphanyl)‐amine (dppa) yields 1:1 P‐monohapto adducts Me2. AuX(dppa), which are in equilibrium with ionic chelated systems Me2Au(dppa)+ X− (1e, f). Complex 1e is readily oxidized by air to the P‐hapto P′‐monoxide cis complex 2e. Treatment of 1e with AgNO3 gives the ionic nitrate Me2. Au(dppa)+ NO3− (1g). – All compounds were identified by standard analytical and spectroscopic techniques. The crystal structures of 2a, 3b, 1d, and 2e were determined by single‐crystal X‐ray diffraction studies.
Kinetic Investigations of the Hydrogenation of Diolefin Ligands in Catalyst Precursors for the Asymmetric Reduction of Prochiral Olefins, II[1]
Authors: Heller Detlef , Borns Susanne , Baumann Wolfgang , Selke Rüdiger
Published: July 2007

Asymmetric hydrogenations of prochiral olefines by means of chiral rhodium(I) complexes of the type [Rh(L)(PP*)]A (L = COD, [(Z,Z)‐cycloocta‐1,5‐diene], or NBD (norborna‐2;5‐diene), PP* = chiral bisphosphane forming seven‐membered chelate rings, A = anion like BF4−) are often associated with induction periods caused by partial blocking of the catalyst. NBD complexes are hydrogenated faster than the corresponding COD complexes. Catalytic hydrogenation of COD/NBD mixtures and the determination of the ratio of the Michaelis constants showed that the steady‐state concentration of the COD complex under hydrogen is higher than that of the NBD complex. However, under argon the NBD complex predominates owing to its higher thermodynamic stability compared with that of the COD complex as determined by 31P‐NMR spectoscopy. This complete reversion of the ther‐modynamically determined ratios of COD to NBD complex concentration under hydrogenation conditions was proven by means of UV/Vis spectroscopy.
Alkali Metal Polyphosphides in Low Dimensions: Synthesis and Structure of [(CH3)4N]2RbP7(NH3) and [(C2H5)4N]Cs2P11
Authors: Korber Nikolaus , von Schnering Hans Georg
Published: July 2007

Partial exchange of the alkali metal ions for tetraalkylammonium cations of Rb3P7 and Cs3P11 in liquid ammonia results in the formation of [(CH3)4N]2RbP7(NH3) (1) and [(C2H5)4N]Cs2P11 (2). The crystal structures reveal the existence of one‐dimensional [RbP7]2− chains in the former and two‐dimensional [Cs2P11]− layers in the latter compound. The nortricyclane cage in 1 is distorted by one‐sided coordination to the Rb ions in a manner that can be related to the valence tautomerism of the free P73− anion.
On the Synthesis of Sulfoxonium Ylides: New Aspects of the Chemistry of 1,3‐Dithietane 1,1,3,3‐Tetraoxide and 1,3,5‐Trithiane 1,1,3,3,5,5‐Hexaoxide
Authors: Sundermeyer Wolfgang , Walch Andreas
Published: July 2007

Sulfoxonium ylides 3a‐h were synthesized by silylation of the cyclic methylene disulfones 1,3‐dithietane 1,1,3,3‐tetraoxide (1) and 1,3,5‐trithiane 1,1,3,3,5,5‐hexaoxide (4) with the silylating agents silyl nonafluorobutanesulfonates. The structure and constitution of the ylides were established with 1H‐NMR, 13C‐NMR, 29Si‐NMR spectroscopy, mass spectrometry, and elemental analysis. On the route to the sulfoxonium ylides a new class of unsaturated disulfenes 7, 8, 12, 13 of 1 and 4 were synthesized via Knoevenagel and substitution reactions. Dianions of newly formed alkyl disulfenes 16a, b, e, f, and the trianion 17 were prepared and characterized by 1H‐NMR and 13C‐NMR spectroscopy and compared with the results of the ylides.
Transition Metal‐Substituted Arsaalkenes, II. Synthesis, Structure and Reactivity of the Arsaalkenes RAs=C(NMe2)2 [R = Me3Si, (η5‐C5Me5)(CO)2Fe] and the 1,2‐Dihydroarsete (η5‐C5Me5)(CO)2‐Fe
Authors: Weber Lothar , Kaminski Olaf , Stammler Hans‐Georg , Neumann Beate
Published: July 2007

Reaction of equimolar amounts of thiuronium salt [(Me2N)2C‐SMe]I (1, with LiAs(SiMe3)2 · 2 THF (2) afforded arsaalkene Me3SiAs=C(NMe2)2 (3). Combination of 3 with (η5‐C5Me5)(CO)2 FeBr led to the formation of (η5‐C5Me5)(CO)2‐FeAs=C(NMe2)2 (4). Reaction of the latter with dimethyl fumarate gave the 1,2‐dihydroarsete (η5‐C5Me5)(CO)2‐Fe (6). Compounds 3, 4, and 6 were characterized by means of spectroscopy (IR, 1H, 13C{1H}, 29Si{1H} NMR and mass spectrometry). The molecular structures of 4 and 6 were determined by X‐ray diffraction analysis.
1‐Bromo‐3,5‐bis(trifluoromethyl)benzene: A Versatile Starting Material for Organometallic Synthesis
Authors: Porwisiak Jacek , Schlosser Manfred
Published: July 2007

1‐Bromo‐3,5‐bis(trifluoromethyl)benzene (1) can be selectively prepared by treatment of 1,3‐bis(fluoromethyl)benzene with N,N'‐dibromo‐5,5‐dimethylhydantoin in strongly acidic media. A number of synthetically useful reactions via 3,5‐bis(trifluoromethyl)phenylmagnesium, ‐lithium, and ‐copper intermediates were accomplished.
Lithiierte Phosphanimine. Synthese und Kristallstrukturen von [LiCH2PMe2NSiMe3]4 und [LiCMe2P(iPr)2NSiMe3]2
Authors: Müller Anita , Neumüller Bernhard , Dehnicke Kurt
Published: July 2007

Lithiated Phosphane Imines. Synthesis and Crystal Structures of [LiCH2PMe2NSiMe3]4 and [LiCMe2P(iPr)2NSiMe3]2

The title compounds were prepared by the reaction of Me3‐SiNPMe3 and Me3SiNP(iPr)3, respectively, with n‐Butylli‐thium at 20°C in n‐hexane solution. They form white, moisture‐ and oxygen‐sensitive crystals, which were characterized by IR spectroscopy and by crystal structure determinations. – [LiCH2PMe2NSiMe3]4 (1) forms a Li4 tetrahedron, the faces of which are capped with CH2 groups with average Li‐C distances of 233 and 251 pm, while the nitrogen atoms occupy the corners of the Li4 tetrahedron. – [LiCMe2P(iPr)2N‐SiMe3]2 (2) forms molecules of symmetry C2 in which the lithium atoms have coordination number three by two carbon atoms and one nitrogen atom with Li‐C distances of 215.2 and 237.9 pm and Li‐N of 192.8 pm.
Phosphorus Analogs of Bipyridines: Their Synthesis and Coordination Chemistry
Authors: Mathey François , Le Floch Pascal
Published: July 2007

The synthesis and coordination chemistry of 2‐(2‐pyridyl)‐phosphinines and 2,2′‐biphosphinines are reviewed. A noteworthy series of homoleptic complexes of 4,4′,5,5′‐tetramethyl‐2,2′‐biphosphinine (tmbp) with Cr(0), Mo(0), Wo(0) and Ni(0) are described. A [Cu(bpy)(tmbp)]+ cationic polymer has been characterized by X‐ray analysis. Ruthenium, manganese and rhenium chelates were also obtained. With Mn2(CO)10, a (tmbp)‐Mn2(CO)6 complex is formed where tmbp acts as an eight electron donor.
Synthesis and Characterization of Titanium Complexes Containing Potentially Tridentate Amido‐cyclopentadienyl Ligands
Authors: Okuda Jun , Du Plooy Karen E. , Massa Werner , Kang Hak‐chul , Rose Ulrich
Published: July 2007

Two new titanium complexes of the general type Ti(η5:η1‐C5H4SiMe2NCH2CH2X)Cl2 (X = NMe2 OMe), containing a tridentate ligand, were prepared by reaction of Ti(η5‐C5H4SiMe2Cl)Cl3 with the lithium amide Li(NHCH2CH2X) (X = NMe2, OMe). The 1HNMR chemical shifts for the protons of the ethylene link were found to vary considerably as a function of the temperature, indicating the presence of an equilibrium between the tri‐ and bidentate bonding mode of the ligand. A single‐crystal X‐ray structural analysis of Ti(η5:η1C5H4SiMe2NCH2CH2OMe)Cl2 revealed that the methoxy function is not intramolecularly coordinated in the solid state.
A Study on Electronic Interaction Between two [2.2]Metacyclophane Systems Connected with a CC Bond: Preparation, Structure and Complexation of (E)‐ and (Z)‐8,8′‐(Ethene‐1,2‐diyl)bis(5‐tert‐butyl[2.2]metacyclophane)
Authors: Ishi‐I Tsutomu , Sawada Tsuyoshi , Mataka Shuntaro , Tashiro Masashi , Thiemann Thies
Published: July 2007

(E)‐8,8′‐(Ethene‐1,2‐diyl)bis(5‐tert‐butyl[2.2]metacyclo‐phane) (2) was obtained from a McMurry reaction of 5‐tert‐butyl‐8‐formyl[2.2]metacyclophane (1). Irradiation of 2 with a high‐pressure mercury lamp gave the corresponding (Z) isomer 3. X‐ray crystallographic analyses of 2 and 3 show a certain degree of twisting of the bond connecting the meta‐cyclophane unit and the central π system due to steric crowding. UV spectra of 2 and 3 and of the charge‐transfer complexes [2/TCNE] and [3/TCNE] allow for a discussion of π‐π interaction between the central stilbene subunit and the outer benzene rings of the metacyclophane units. Bis[2.2]meta‐cyclophanes 2 and 3 reacted regioselectively with hexacar‐bonylchromium on the outer benzene rings giving 1:1 and 1:2 complexes 9–14 with tricarbonylchromium. No 1:3 and 1:4 complexes formed due to steric restrictions. Analysis of UV spectral data of the complexed [2.2]metacyclophanes was performed for an indication of π‐π interactions in the complexes.
Preparation, Characterisation and Reactivity of Neutral Mono‐η4‐oxadiene Complexes of Molybdenum and Tungsten Containing Bidentate Donor Ligands
Authors: Schmidt Thomas , Bienewald Frank , Goddard Richard
Published: July 2007

Neutral molybdenum and tungsten complexes containing only one η4‐coordinated 1‐oxa‐1,3‐diene ligand are obtained diastereospecifically from the reaction of the corresponding dicarbonylbis(oxadiene) complexes with bidentate donor ligands capable of forming five‐membered ring chelates. Thus, dicarbonylbis[η4‐(R)‐(+)‐pinocarvone]metal complexes react with 1,2‐bis(dimethylphosphanyl)ethane (dmpe) or N,N,N′,N′‐tetramethylethylenediamine (tmeda) to give the mono(oxadiene) compounds 1 – 4 in 45–95% yield. The molecular structure of the dmpe‐tungsten complex 3 was determined by X‐ray structural analysis Spectroscopic data indicate that an effective transfer of electron density from the donor atoms occurs. This is also reflected in a decreased reactivity of the carbonyl ligands in the mono(oxadiene) complexes towards nucleophilic alkylation. As a result, the selectivity in the alkylation (a formal “Umpolung” reaction) of anionic intermediates generated from 2 and methyllithium with carbon electrophiles is greatly improved, allowing access to alkylation products, e.g. 5, that are otherwise difficult to obtain.
Complexes with S‐Donor Ligands, 4. Mono‐ and Di‐Homo‐ and ‐Hetero‐Nuclear Gold(I), Silver(I), and Palladium(II) Complexes with 2‐(Methylthio)pyridine, Pyridine‐2(1H)‐thione, and Benzoxazole‐2(3H)‐thione. Some Examples of the Use of Complexes as Ligands
Authors: Vicente José , Chicote María‐teresa , Rubio Concepción
Published: July 2007

AgClO4 reacts with bidentate ligands 2‐(methylthio)pyridine (SMepy) or complexes PPN[Au(Spy)2] [PPN = N(PPh3)2, HSpy = pyridine‐2(1H)‐thione) or PPN[Au(Sbz)2] (HSbz = benzoxazole‐2(3H)‐thione), themselves acting as ligands, to give dinuclear complexes [Ag2(μ‐SMepy)2](ClO4)2 (1), [AgAu(μ‐Spy)2] (2), or [AgAu(μ‐Sbz)2] (3), respectively. By treating 1 with [AuCl(tht)] (tht = tetrahydrothiophene), [Au(SMepy)(tht)]ClO4 (4) is obtained which, in turn, reacts with SMepy to give [Au(SMepy)2]ClO4 (5). Similarly, [PdCl2(NCPh)2] reacts with SMepy in 1:1 molar ratio to give [Pd2Cl2(μ‐Cl)2(SMepy)2] (6) which reacts with SMepy in 1:2 molar ratio to give [PdCl2(SMepy)2] (7). On the other hand, HSpy reacts with Ag2CO3 to give [Ag2(μ‐Spy)2] (8), and (SMepyH)ClO4 reacts with [Au(acac)PPh3] (acacH = acetyl‐acetone) to give [Au(SMepy)PPh3]ClO4 (9).
Zinc Complexes of Amino Acids and Peptides, 6. Zinc Complexes of Oligopeptides Containing Histidine at Both Termini
Authors: Förster Martin , Brasack Ingo , Duhme Anne‐Kathrin , Nolting Hans‐Friedrich , Vahrenkamp Heinrich
Published: July 2007

One tripeptide, five tetrapeptides, and one pentapeptide, all containing His–Xn–His sequences and being blocked at the N and C termini with acyl and amide functions, respectively, were synthesized by solid‐phase methods. With one exception their reaction with various zinc salts led to the precipitation of 1:1 (zinc/peptide) complexes. Analytically pure compounds were obtained from zinc tetrafluoroborate and His–Gly–His (1), from zinc chloride (resp. bromide) and His–Gly –Gly–His (2), His–Ala–Gly–His (3), His–Leu–Gly–His (4), His–Pro–Gly–His (5), and His–Pro–Asn–His (6) as well as from zinc sulfate and His–Leu–Gly–His (4) and His–Ala–Pro–Gly–His (7).1H‐NMR data, when available, indicate the coordination of both histidine units to zinc in all cases. The low solubility of the complexes points to their polymeric nature. The only 1:2 (zinc/peptide) complex in this series was obtained from zinc perchlorate and His–Gly–Gly–His (2). An EXAFS study revealed that it contains zinc symmetrically coordinated by four histidine imidazole ligands. Based on the available information it is proposed that all complexes are one‐dimensional polymers containg [–Zn–His–Xn–His–Zn–]xbackbones.
Novel trialkylstibane iridium(I) and iridium(III) complexes including the x‐ray crystal structure of five‐Coordinate [IrCl(C2H4)2(SbiPr3)2]
Authors: Werner Helmut , Ortmann Dagmara A. , Gevert Olaf
Published: July 2007

The reaction of [IrCl(C8H14)2]2 (2) with SbiPr3 in the presence of H2 yields the dihydridoiridium(III) complex cis,mer‐[IrH2Cl(SbiPr3)3] (3) which on treatment with CO and with HCCR (R = Ph, CO2Me) affords the octahedral derivatives [IrH2Cl(CO)(SbiPr3)2] (4) and [IrHCl(CCR)(SbiPr3)3] (5, 6), respectively. The stibane ligand trans to hydride in 5 and 6 is rather labile and, therefore, 5 and 6 react with pyridine to give [IrHCl(CCR)(py)(SbiPr3)2] (7, 8). Five‐coordinate bis‐(stibane)iridium(I) complexes [IrCl(C2H4)2(SbR3)2] (10–12) were prepared from [IrCl(C2H4)2]2 (9) and four equiv. of SbR3 (R = iPr, Me, Ph). The X‐ray crystal structural analysis of 10 reveals a distorted trigonal‐bipyramidal geometry around the metal center with one stibane ligand and the two olefinic ligands in the equatorial plane. Compound 10 reacts with NaC5H5 to yield [C5H5Ir(C2H4)(SbiPr3)] (13) and with different alkynes by partial or complete displacement of the ethene ligands to give trans‐[IrCl(PhCCPh)(SbiPr3)2] (14), [IrHCl(CCTol)(C2H4)(SbiPr3)2] (15), and trans‐[IrCl‐{CC(SiMe3)R}(SbiPr3)2] (16, 17), respectively.
The chemistry of metallacyclic alkenylcarbene complexes, 3. CC bond formation with carbon nucleophiles. stereoselective dienylation of lithium enolates and cuprates and a novel cascade synthesis of highly substituted cyclopentenones from lithium acetylides
Authors: Böhmer Jutta , Förtsch Walter , Hampel Frank , Schobert Rainer
Published: July 2007

The cationic ferracyclic carbene complexes 1 react with carbon nucleophiles like lithium enolates and organocuprates to give the corresponding 4‐substituted 1, (3E)‐diene tricarbonyl‐iron complexes 6 and 9. The reaction is thought to proceed by initial attack on the allyl terminus and subsequent ferra Claisen‐Ireland rearrangement of the intermediate (η2 alkene)carbene complex 4. This rationale is supported by the isolation and characterisation of analogous aminooxocarbene derivatives 8. With sterically demanding enolates products 6 are formed in diastereomeric ratios of up to 90:10, thus demonstrating the inductive power of the chiral metallacycle in 1. Lithium acetylides as carbon nucleophiles react with 1 according to a novel cascade to give regio‐ and stereospecifically 2,5,5‐trisubstituted‐cyclopentenones 10 suggesting a concerted formation of four CC bonds together with a CO insertion and a formal carbene transfer step.
A New Reagent for Nucleophilic Aminomethylation: Doubly Lithiated Bis(dimethylamino)methane and Its Use for the Synthesis of Si,N‐Heterocycles
Authors: Karsch Hans H.
Published: July 2007

The aminal Me2NCH2NMe2 is doubly metalated by LitBu to give LiCH2N(Me)CH2N(Me)CH2Li, which reacts with chlorosilanes to afford the respective silylated species, including the six‐membered heterocycle Me2SiCH2N(Me)CH2N(Me)‐CH2 and the spiroheterocycle Si[CH2N(Me)CH2N(Me)CH2]2.
On the Chemistry of Gallium, 8. Synthesis and Structure of [Tris(trimethylsilyl)silyl]‐Substituted Gallanes and Gallates
Authors: Linti Gerald , Frey Ronald , Köstler Wolfgang , Urban Horst
Published: July 2007

Reaction of lithium tris(trimethylsilyl)silanide · 3 THF with R2GaCl (R = 2,2,6,6‐tetramethylpiperidino, Me, Cl) yields tmp2GaSi(SiMe3)3 (3) and R2Ga(THF)Si(SiMe3)3 (R = Me, Cl) (7, 9). Both gallium nitrogen bonds in 3 are cleaved by protic reagents. Depending on the acidity of these agents, either oligomeric gallanes [(RO)2GaSi(SiMe3)3]n (R = Et, H, n = 2, 3) (11, 12) or tetramethylpiperidinium gallates [X3GaSi‐(SiMe3)3]– (X = OPh, Cl) (13, 14) are formed. Hydroxide 11 adds lithium hydroxide to afford the mixed lithium gallium hydroxide 15. Single‐crystal X‐ray diffraction studies confirm the suggested constitutions. The gallium‐silicon bond can adopt values between 236 and 247 pm. Here electronic influences of the substituents on the gallium center are of great importance as well as their steric demand. This is underlined by quantum chemical calculations on the ab initio (SCF) level.
cis‐ and trans‐Dimolybdenum(II) Complexes with Asymmetrically 2,7‐Disubstituted Naphthyridines as Bridging Ligands
Authors: Mintert Markus , Sheldrick William S.
Published: July 2007

Treatment of [Mo(CO)6] with Hmamnp (2‐acetamido‐7‐methyl‐1,8‐naphthyridine) in diglyme at 100°C affords the mononuclear complex [Mo(CO)4(Hmamnp)] 1, an intermediate product on the reaction pathway to tetrasubstituted species of the type [Mo2L4]. A disubstituted intermediate product cis‐[Mo2(mphamnp)2(OAc)2] 2 (Hmphamnp) (2‐acetamido‐5‐methyl‐7‐phenyl‐1,8‐naphthyridine) may be isolated from the reaction of [Mo2(OAc)4] with mphamnp– in THF. The relative stabilisation of such products is a result of the steric demands of the coplanar 2‐acetamido substituents. 2 and the tetrasubstituted complexes trans‐[Mo2(mbznnp)4] 3 (Hmbznnp = 2‐benzylamino‐7‐methyl‐1,8‐naphthyridine), cis‐[Mo2(mphonp)4] 4, and trans‐[Mo2(mphonp)4] 5 (Hmphonp = 5‐methyl‐7‐phenyl‐1,8‐naphthyridin‐2‐one) all exhibit the electronically prefered μ‐N1,X2 bridging mode. Steric effects are responsible for the isolation of the unusual cis isomer 4.
Chirale Tripod‐Liganden mit Phosphit‐Donorgruppe: Synthese und Komplexchemie
Authors: Scherer Johannes , Huttner Gottfried , Büchner Michael
Published: July 2007

Chiral Tripodal Ligands Bearing a Phosphite Donor Group: Synthesis and Coordination Chemistry

The mechanism of the reaction of epichlorohydrine (H–CH2Cl) (1) with lithium phosphides is analysed. A neighbouring‐group mechanism has been found to be the essential driving force in this reaction. Monophosphanyl alcohols such as HOCH(CH2P(Ph)2)(CH2Cl) (2) and epoxides (Ph)2PCH2– (3) are characterized as intermediates. The mechanism leads to a rapid one‐pot method for the synthesis of chiral racemic as well as enantiomerically pure bis(phosphanyl) alcohols HOCH(CH2PR2)(CH2PR) (4). The resulting bis(phosphanyl) alcohols 4 react easily with X2PCl (X = Cl; Ph; or X2 = 1,2‐ethanedioxy‐2,2′‐biphenyldiyldioxy‐) to yield the mixed donor group tripodal ligands X2POCH(CH2PR2)(CH2PR′2) (5, 6) containing both phosphite, phosphinite or phosphorodichloridite and phosphane donor groups. The identity of these compounds were proved by 1H‐, 31P‐ and 13C‐NMR spectroscopy, mass spectra, microanalysis as well as X‐ray analysis. The coordination capabilities of these novel ligands are demonstrated by the synthesis and characterization of a (cyclooctadiene)rhodium complex {[(5c)Rh(I)COD]PF6} (7) of the ligand 5c, exhibiting the typical hetero‐bicyclooctane tripod metal cage of this type of tripod complexes.
Electrochemical Preparation of Nanostructured Titanium Clusters: Characterization and Use in McMurry‐Type Coupling Reactions
Authors: Reetz Manfred T. , Quaiser Stefan A. , Merk Claudia
Published: July 2007

The electrochemical preparation of nanostructured titanium clusters is possible by using a titanium sacrificial anode as the metal source and tetrabutylammonium bromide in THF as the electrolyte and stabilizer. Transmission electron microscopy shows the presence of spherical 3.0‐nm‐sized particles. THF solutions of these Ti clusters induce olefin‐forming McMurry‐type coupling of aldehydes and ketones.
Syntheses and Photochemistry of Fluorinated and Chlorinated Titanium Porphyrinates: Crystal Structure of Oxotitanium meso‐Tetrakis(2,3,4,5,6‐pentafluorophenyl)porphyrinate
Authors: Esser Peter E. , Englert Ulli , Keim Wilhelm
Published: July 2007

The syntheses of oxotitanium(IV) meso‐tetrakis(2,3,4,5,6‐pentafluorophenyl)porphyrinate O=Ti(TPPF20) (1), oxotitanium(IV) meso‐tetrakis(2,6‐difluorophenyl)porphyrinate O=Ti‐(TPPF8) (3), and oxotitanium(IV) meso‐tetrakis(2,6‐dichlorophenyl)porphyrinate O=Ti(TPPCl8) (5) from titanium tetrachloride and the corresponding porphine are described. The structure of 1 was determined by single‐crystal X‐ray diffraction. The reaction of oxotitanium porphyrinates with aqueous hydrogen peroxide leads to the corresponding light‐sensitive peroxotitanium(IV) complexes: Ti(O2)(TPPF20) (2), Ti(O2)‐(TPPF8) (4), Ti(O2)(TPPCl8) (6). All complexes are efficient and stable photosensitizers for the generation of singlet oxygen.
Zinc Complexes of Amino Acids and Peptides, 7. Solution Behavior and Zinc Complexation of Dipeptides Made up Solely from Histidine and Cysteine
Authors: Gockel Peter , Vogler Raphael , Vahrenkamp Heinrich
Published: July 2007

The eight possible types of dipeptides made up from histidine and cysteine, namely the unprotected ones H‐His‐Cys‐ OH (1) and H‐Cys‐His‐OH (2), the N‐protected ones Ac‐His‐Cys‐OH (3) and Ac‐Cys‐His‐OH (4), the C‐protected ones H‐His‐Cys‐OEt (5) and H‐Cys‐His‐NH2 (6), and the fully protected ones Ac‐His‐Cys‐OEt (7) and Ac‐Cys‐His‐OEt (8) were prepared analytically pure. Their acid‐base behavior and zinc complexation in solution were studied potentiometrically. In all cases 1:1 (zinc:peptide) complexes are the dominant species near neutral pH. 1:2 complexes could only be detected for 4, 6, 7, and 8, and precipitations occurred in basic media. From equimolar mixtures of the peptides and zinc salts (chloride, iodide, perchlorate) solid complexes were obtained upon addition of a base. They always contain coordinating anions (chloride, iodide, or trifluoroacetate which was introduced with the peptide). They have the composition LZnX for L = 5‐8 and L4Zn5X2 for L = 1–4. It is proposed that all complex species observed contain tetrahedral zinc, that they are monomers in dilute solution and thiolate‐bridged oligomers in the solid state, and that the peptides as a rule occupy at least three coordination sites.
Twofold Insertion of Isocyanides into the GaGa Bond of Tetrakis[bis(trimethylsilyl)methyl]digallane(4)
Authors: Uhl Werner , Hahn Ingo , Schütz Uwe , Pohl Siegfried , Saak Wolfgang , Martens Jürgen , Manikowski Jens
Published: July 2007

Tetrakis[bis(trimethylsilyl)methyl]digallane(4) (1) reacts with tert‐butyl or aryl=isocyanides [aryl = phenyl, o‐methylphenyl, o‐methoxyphenyl, p‐methoxyphenyl) by a twofold insertion of the central carbon atoms into the Ga–Ga bond and formation of C–C single bonds. 1,4‐Diazabutadiene derivatives bound to two R2Ga groups are formed (2–6), which in contrast to an aluminium analog exhibit only weak interactions between the imine nitrogen atoms and the coordinatively unsaturated gallium atoms as indicated by NMR spectroscopy and the long Ga–N distances in the molecular structures of three products: 2 (R = C6H5), 4 (R = o‐MeOC6H4), and 6 (R = CMe3).
ansa‐Titanocene and ‐Zirconocene η2‐Alkyne Complexes ‐Synthesis, Spectral Characteristics, and X‐ray Crystal Structure
Authors: Peulecke Normen , Lefeber Claudia , Ohff Andreas , Baumann Wolfgang , Tillack Annegret , Kempe Rhett , Burlakov Vladimir V. , Rosenthal Uwe
Published: July 2007

The reduction of the complex [(η5‐C5H4)‐ansa‐(η5‐C5H4)]TiCl2 with magnesium in the presence of Me3SiC2‐SiMe3 in THF at room temperature gives the ansa‐titanocone alkyne complex [(η5‐C5H4)‐ansa‐(η5‐C5H4)]Ti(η2‐Me3SiC2‐SiMe3) (ansa = Me2Si‐O‐SiMe2, 1). The similar pyridine‐stabilized zirconium complexes could be obtained by analogous reactions and addition of pyridine: [(η5‐C5H4)‐ansa‐(η5‐C5H4)]Zr(L)(η2‐Me3SiC2SiMe3) (ansa = Me2Si‐O‐SiMe2, L = pyridine: 2; ansa = SiMe2, L = pyridine: 3). All complexes were characterized by spectroscopic methods. An X‐ray structure determination of complex 3 was conducted, and the data were compared to those of the complexes rac‐(EB‐HI)Zr(L)(η2‐Me3SiC2SiMe3) [L = (S)‐(‐)‐nicotine: 6, EBHI = ethylenebis(tetrahydroindenyl)] and Cp2Zr(py)(Me3SiC2‐SiMe3).
Control of Regioselectivity in the Transition‐Metal‐Catalysed Conjugate Additions of Alkylaluminium Compounds and Methyltitanium Ate Complexes to Androsta‐1,4‐diene‐3,17‐dione
Authors: Westermann Jürgen , Neh Harribert , Nickisch Klaus
Published: July 2007

By a variation of the nature of the reagent system conjugate addition to the cross‐conjugated steroidal dienone 1 occurs selectively either at C‐1 or at the sterically hindered C‐5. With Me3Al or Me4AlLi in the presence of catalytic amounts of Cu1 salts, a high regioselectivity (up to 97:3) in favour of position 1 is achieved. Application of ate complexes of aluminium and titanium in the presence of Ni(acac)2 as catalyst, however, leads to a reversal of the regioselectivity in favour of position 5 (up to 11:89). Aluminium and titanium ate complexes are efficient reagents in the Ni(acac)2‐catalysed conjugate addition to sterically hindered enones.
Synthesis and Characterisation of Ionic Ozonides with Bisquaternary Ammonium Counterions
Authors: Seyeda Hady , Armbruster Klaus , Jansen Martin
Published: July 2007

The bisquaternary ammonium ozonides Me3N+(CH2)n +NMe3(O3‐)2 with n = 3, 4, 6 (1, 2, 3), Me3N+(CH2)3+NMe3(O3‐)2 · 3 NH3 (1a), Me3N+(p‐Ph)+NMe3(O3‐)2 (4) and Me3N+(p‐Ph)+NMe3(O3‐)2 · NH3 (4a) were obtained in quantitative yields by cation exchange starting from CsO3. The compounds 1a and 3 have been studied by single crystal X‐ray analysis. The influence of C–H…O and N–H…O hydrogen bonds on the bond length and the bond angle of the ozonide anion is discussed; earlier results are included. The difference between the two bond lengths within the O3‐ ion [137.4(3) pm and 129.5(3) pm] in 1a is unexpectedly large. Thermal stabilities determined by DTA/TG methods range from 24–83°C.
Synthesis and Dynamic Behavior of the Dimeric, Monocyclic Barium Bis[bis(isopropyldimethylsilyl)phosphanide] – Molecular Structures of P(SiMe2Ph)3, of Monomeric (thf)4Ba[P(SiMe2iPr)2]2 and of the Dimer {(thf)2Ba[P(SiMe2iPr]2]2}2
Authors: Westerhausen Matthias , Lang Gerhard , Schwarz Wolfgang
Published: July 2007

Barium bis[bis(trimethylsily)amide] metalates bis(isopropyldimethylsilyl)phosphane (1) to yield nearly quantitatively the corresponding barium bis[bis(isopropyldimethylsilyl)phosphanide] (3). This compound shows a temperature‐dependent monomer‐dimer equilibrium in toluene solution. Both the isomers were characterized by X‐ray crystal structure analyses. The monomeric derivatives precipitate as a tetrakis(tetrahydrofuran) complex with a P–Ba–P bond angle of 139.9°. The barium atoms of the monocyclic, centrosymmetric dimer are pentacoordinated by two tetrahydrofuran molecules, one terminal and two bridging phosphanide ligands. The endo‐ and exocyclic Ba–P distances with values of 332 and 316 pm, respectively, lie within the characteristic range.
Activation of Molecular Oxygen by Biomimetic Schiff Base Complexes of Manganese, Iron, and Cobalt
Authors: Jäger Ernst‐Gottfried , Knaudt Jutta , Rudolph Manfred , Rost Michael
Published: July 2007

The metal complexes (E,E)‐[{diethyl 2,2′‐[1,2‐phenylenebis(iminomethylidyne)]bis[3‐oxobutanoato]}(2–)‐N,N′,O3,O3′]manganese (Mn1a), [3,3′]‐[1,2‐phenylenebis(iminomethylidyne)bis(2,4‐pentanedionato)(2–)‐N,N′,O2,O2′]manganese (Mn1b), and (Z,Z)‐[diethyl 3,3′‐(1,2‐phenylenediimino)bis(2‐cyano‐2‐propenoato)](2–)‐N3,N3′,O1,O1′]manganese (Mn1c) were sythesised and the oxygenation of these complexes was investigated by gas volumetry. All complexes except Mn1c are able to take up oxygen but with different magnitudes. The catalytic activity of the Mn, Co, and Fe complexes of the ligands 1a and 1c and (E,E)‐[{diethyl 2,2′‐[1,2‐ethylenebis(iminomethylidyne)]bis[3‐oxobutanoato]} (2–)N,N′,O3,O3′] iron (Fe1d) and [diethyl (all‐E)‐5,14‐dihydro‐6,17‐dimethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine‐7,16‐dicarboxylato)(2–)‐N5,N9,N14,N18]iron (Fe2a) has been compared with respect to the oxidation of hydroquinone by molecular oxygen. The results are interpreted with the aid of electrochemical properties, Lewis acidities, and other relevant factors. However, no simple relationship between the catalytic activity and the other factors could be found.
Preparation and Structure of Dithioxo‐ and Diselenoxophosphoranes Stabilized by Intramolecular Coordination with a Dialkylamino Group
Authors: Yoshifuji Masaaki , Sangu Shinya , Kamijo Kazunori , Toyota Kozo
Published: July 2007

Some dithioxophosphoranes 3 stabilized by intramolecular coordination with a dialkylamino group were prepared, and their structures were analyzed by X‐ray crystallography involving [2,4‐di‐tert‐butyl‐6‐(isopropylmethylamino)phenyl]‐ (3c), {2,4‐di‐tert‐butyl‐6‐[(dimethylamino)methyl]phenyl}‐ (3f), and {2,4‐di‐tert‐butyl‐6‐[2‐(dimethylamino)‐1,1‐dimethylethyl]phenyl}dithioxophosphorane (3h). The bond between the phosphorus atom and the aromatic ring is flexible and the angle narrows with decreasing ring size of the intramolecular coordination. The 31P‐NMR signals are shifted to higher field with increasing ring size of the intramolecular coordination or strength of coordination. Similarly, the corresponding diselenoxophosphoranes 4 were prepared. Both their 31P‐ and 77Se‐NMR signals are shifted to higher field with increasing contribution of intramolecular coordination.
Diphosphonio‐1,2‐diphospholes: Structural PIII/Pv Hybrids
Authors: Jochem Georg , Nöth Heinrich , Schmidpeter Alfred
Published: July 2007

P‐Methylation of the 3,5‐bis(triphenylphosphonio)‐1,2‐diphospholide 1 leads to the dicationic diphosphole 3a. A crystal of its bis(triflate) was used for a structure analysis. It indicates that in contrast to the known phospholes the cyclic π6 system is preserved in 3a. The coordination geometry of the methylated phosphorous atom shows a flat pyramid with a sum of angles of 339°. Therefore, 3a represents a state that is intermediate between a phosphane and a bis(methylene)phosphorane, i.e. between PIII and Pv.
Chiral Homoenolate Equivalents, V. Hydroxylakylation of Lithiated 3‐[(S)‐2‐(Methoxymethyl)pyrrolidino]‐1,3‐diphenylpropene – An Asymmetric Homoaldol Reaction
Authors: Ahlbrecht Hubertus , Kramer Andreas
Published: July 2007

The hydroxyalkylation of lithiated 3‐[(S)‐2‐(methoxymethyl)‐pyrrolidino]‐1,3‐diphenylpropene (2) with aldehydes is completely regioselective giving homoaldol adducts in good yields. The simple diastereoselectivity is low with typical ratios ranging between 1:1 and 1:3 with the syn isomer predominating. The induced diastereoselectivity is much higher and is strongly solvent‐dependent. The reaction predominantly proceeds according to a metalloretentive mechanism from the si side of the allylic system in THF as well as in TBME. The induced diastereoselectivity obtained by the use of the less solvating TBME is considerably higher than in the strongly solvating THF, selectivities of up to 97% ee being reached.
Thietane and Selenetane Complexes by Thermal Cycloaddition of Vinyl Ethers to Transition‐Metal‐Coordinated Thio‐ and Selenoaldehydes – Crystal Structure of Pentacarbonyl(7‐phenyl‐2‐oxa‐8‐thiabicyclo[4.2.0]octane‐S)tungsten(0)
Authors: Fischer Helmut , Kalbas Claudia , Sumpf Rüdiger
Published: July 2007

Pentacarbonyl(thiobenzaldehyde)tungsten und pentacarbonyl(selenobenzaldehyde)tungsten (1a and 1b) undergo a thermal [2 + 2] cycloaddition with several vinyl ethers to give highly substituted transition metal‐coordinated thietanes and selenetanes. The addition is highly regio‐ and stereospecific. The products undergo acid‐catalyzed rearrangements, which lead to thermodynamically more stable diastereomers of the thietanes and selenetanes. The stereochemistry of both addition and rearrangement was established by reaction of deuterium‐labeled vinyl ethers and by reaction of the cis and trans isomers of ethyl propenyl ether. The crystal structure of the bicyclic addition product of 1a and 3,4‐dihydro‐2H‐pyran is reported.
Synthesis and X‐ray Crystal Structure of the First Mononuclear Nickel(II) Alkane Thiolate Complex with a Mixed (S,N,N,O) Ligand Field
Authors: Berkessel Albrecht , Bolte Michael , Neumann Thomas , Seidel Lutz
Published: July 2007

The six‐step synthesis of a chiral, pentadentate dihydrosalen ligand, carrying a mercaptomethyl group as additional binding site, is described. When this ligand was treated with nickel(II) salts, a planar tetracoordinated nickel chelate was obtained, and not the expected pentacoordinated species. This complex was fully characterized, including X‐ray crystallography. The crystal structure revealed that the nickel ion is coordinated by the thiolate anion, both the amine and the imine nitrogen atoms of the ligand, and by one phenolate anion. The second phenolic oxygen atom of the ligand does not participate in the coordination of the nickel ion. This chelate is the first mononuclear nickel(II) thiolate complex having a mixed (S,N,N,O) ligand field. Cyclic voltammetry did not indicate a reduction up to –2.1 V (vs. Fc/Fc+). In the anodic range, no reversible but two irreversible oxidation processes were observed.
The Unexpected Formation of a Tetradentate Tripyrrolic Complex of Nickel(II)
Authors: Br ückner Christian , Mar Eduardo K. , Rettig Steven J. , Dolphin David
Published: July 2007

(2‐Pyrrolylmethane)(2‐pyrrolylmethyl)imine (2) and an equimolar amount of 2‐formylpyrrole give, in the presence of nickel(II) in hot methanol, the novel tripyrrolic nickel(II) complex [SP‐4]‐[(2‐dipyrrinato‐k2N,N′‐methyl)(2‐pyrrolylmethenato‐ kN′′)imine‐kN′′′]nickel(II) (4). This planar complex has been characterized by X‐ray crystallography, a mechanism for its formation is proposed and its mass spectral behavior is discussed.
Fluxionality and Phosphane Arm‐off Reactions of Octahedral Rhodium(III) Complexes with the Tripodal Polyphosphane MeC(CH2PPh2)3
Authors: Brandt Katja , Sheldrick William S.
Published: July 2007

Treatment of [RhCl3(triphos)] or [Rh(MeCN)3(triphos)](CF3SO3)3 [triphos= MeC(CH2PPh2)3] with Na(S2C‐NEt2) affords the complexes [RhCl(S2CNEt2)(triphos)]Cl (1) and [Rh(S2CNEt2)(MeCN)(triphos)](CF3SO3)2 (2). Whereas 1 is stereochemically rigid in solution at 25°C, 2 and the analogous complex [Rh(S2CNBz2)(MeCN)(triphos)](CF3SO3)2 (3) exhibit a rapid exchange of their phosphorus environments. In contrast, the 31P‐NMR spectra of both 2 and 3 at –30°C consist of well‐resolved A2MX spin systems. k2P‐coordinated complexes of the type [Rh(S2CNR2)2(triphos‐k2P)]+ (R = Et 4, R = Me 5) with ABX spin systems may be obtained by treatment of the starting compounds with two equivalents of the respective dialkyl dithiocarbamate. The dangling phosphane arm can be readily oxidised to a phosphane oxide as in [Rh(S2CNEt2)2(triphosO‐k2P)]Cl (6) [triphosO = O=P(Ph)2CH2C(Me)(CH2PPh2)2]. The analogous compound [Rh(mpy)2(triphosO‐k2P)]Cl (7) (Hmpy = 2‐mercaptopyridine) was isolated as the OC‐6‐13 isomer with trans‐positioned sulphur atoms, a siting which is in accordance with a reaction mechanism involving a phosphane arm‐off k3P' k3P dissociation equilibrium.
Coordination Chemistry with CF Units as σ Donors: Ag+Complexes of Partially Fluorinated Crown Ethers with Direct Metal–Fluorine Interactions
Authors: Plenio Herbert , Diodone Ralph
Published: July 2007

The partially fluorinated cryptandsFN2O4andBenzoFN2O4, which are relatives of the [2.2.1]cryptand, were synthesized in good yields from 1,3‐bis(bromomethyl)‐2‐fluorobenzene and diaza‐18‐crown‐6 or benzodiaza‐18‐crown‐6, respectively. These macrobicyclic ligands form very stable complexes with Ag(I) salts, and it was shown that close fluorinesilver interactions occur in solution as well as in the solid state. Numerous experimental evidence for this is available: NMR competition experiments show that Ag+complexes ofFN2O4are significantly more stable than those ofHN2O4(the two ligands are identical except that one fluorine atom is replaced by one hydrogen atom inHN2O4); the1JCFcoupling constants of Ag+·FN2O4and Ag+·BenzoFN2O4are reduced by 10 Hz compared to those of the respective free ligandsFN2O4(1JCF=253 Hz) andBenzoFN2O4. (1JCF=252 Hz). The X‐ray crystal structure of Ag+·FN2O4revelas short Ag+–F distances [271.4(3) pm]; coupling of the107,109Ag+and19F nuclei is observed in the19F‐NMR spectra (J=24 Hz for Ag+·FN2O4,J=25 Hz for Ag+·BenzoFN2O4). The1H‐NMR spectrum of Ag+·FN2O4is very complex and exhibits sixteen unique proton resonances, whose evaluation yielded coupling constants and NOEs, which show that the structure in solution is compatible with the results obtained by the X‐ray crystal structure determination.
Contributions to the Chemistry of Boron, 233. Reactions of a 1,2,3,4‐Diphosphadiboretane with Some Carbonylmetal Compounds
Authors: Grundei Stefan , Nöth Heinrich , Paine Robert T.
Published: July 2007

1,2‐Di‐tert‐butyl‐3‐(diisopropylamino)‐4‐(dimethylamino)‐ 1,2,3,4‐diphosphadiboretane (1) reacts with Fe2(CO)9 to give two isomeric tetracarbonyliron complexes 2, 3 with P–Fe bonds and a bis(tetracarbonyliron) complex 4. In contrast, 1 displaces the olefinic ligand from tetracarbonyl(η4‐norbornadiene)metal (metal = Cr, Mo) to form the tetracarbonylmetal complexes 5 and 6 with a rearranged ligand molecule, i.e. a 1,3,2,4‐diphosphadiboretane. This process is accompanied by a change of the tert‐butyl groups from an anti orientation in 1 to a syn orientation in 5 as shown by X‐ray crystallography.
Zinc Complexes of Amino Acids and Peptides, 8[]. Difunctional Dipeptides Containing Cysteine or Histidine: Solution Behavior and Zinc Complextion
Authors: Gockel Peter , Vahrenkamp Heinrich
Published: July 2007

The dipeptides Ac–Cys–Val–OH (1a) and Ac–His–Val–OH (1b), H–Gly–Cys–OEt (2a) and H–Val–His–OEt (2b) as well as Z–Asp–Cys–OH (3a) and Z–Asp–His–OH (3b) (Z = benzyloxycarbonyl) were prepared, and their zinc complexation was investigated by potentiometric methods. They have in common that in addition to the cysteine thiolate or the histidine imidazole the second amino acid offers one donor function. The complex stabilities are very close to those of the corresponding difunctional derivatives of the single amino acids cysteine or histidine. This indicates the presence of seven‐ to ten‐membered chelate rings.
Zinc Complexes of Amino Acids and Peptides, 9[]. Coordination of Cysteine and Histidine Derivatives to the Pyrazolylborate‐Zinc Unit
Authors: Ruf Michael , Burth Rainer , Weis Karl , Vahrenkamp Heinrich
Published: July 2007

Highly substituted pyrazolylborate ligands TpR,Me were used to limit the coordination number of zinc towards cysteine‐ and histidine‐derived coligands. Monodentate thiolate attachment (→ 1a–f) was achieved with N‐ and C‐protected cysteine, monodentate carboxylate attachment (→ 3) with N‐protected histidine. C‐protected cysteine was found to form a five‐membered N,S‐chelate ring (2). While imidazole coordination with N‐ and C‐protected histidine could not be achieved, cationic pyrazolylborate‐zinc‐coligand complexes [TpZn–L]+ (4a, b) were obtained for L = 2‐methylimidazole. The new complexes were characterized by their spectra and three structure determinations.
Reactive E=C [p‐p]π Systems, 45[]. 1‐Aza‐3,4‐diphospholenes by [3 + 2] Cycloaddition of 2‐(Diisopropylamino)phosphaethyne to Diazo Derivatives R1R2C=N2
Authors: Grobe Joseph , Van Duc Le , Immel Franz , Krebs Bernt , Läge Mechtild
Published: July 2007

The reaction of the (diisopropylamino)phosphaethyne (1) with diazo compounds of the type R1R2C=N2 (2a–2c) unexpectedly leads in high yields (60–90%) to the 1‐aza‐3,4‐diphospholene derivatives 3a–3c, a new class of heterocycles. NMR investigations of the analogous reaction of 1 with diazocyclopentadiene 2d show that the multi‐step formation of 3a–3c proceeds via the 1‐aza‐3,4‐diphospholes 6a–6d as intermediates.
Controlled Hydrolysis of Tripodal Titanium Amido Halides: The Influence of the Ligand Periphery upon the Basicity of the Amido‐N Functions
Authors: Friedrich Stefan , Gade Lutz H. , Li Wan‐Sheung , McPartlin Mary
Published: July 2007

Hydrolysis of the tripodal amidotitanium halides H3CC(CH2NSiMe3)3TiX (X = Cl: 1a; Br: 1b) in the presence of Et3N affords the linear μ‐oxo‐bridged complex [H3CC(CH2NSiMe3)3Ti]2 (μ‐O) (3) which was characterized by X‐ray crystallography. Treatment of H3CC(CH2NiPr)3TiX (X = Cl: 2a; Br: 2b), obtained in low yields, under the same conditions only leads to decomplexation of the amido ligand. Under conditions of very slow exposure to H2O the primary addition product of water across two Ti–N bonds in 2a could be isolated and was characterized as [H3CC(CH2‐i(μ‐Cl)]2(μ‐O) (4), the crystal structure analysis establishing a triply bridging central Ti(μ‐O)(μ‐Cl)2 Ti unit. Deprotonation with two molar equivalents of nBuLi and subsequent LiCl elimination afforded the μ‐oxo complex [H3CC(CH2NiPr)3Ti]2(μ‐O) (5).