Zweikernige Palladium(II)‐, Platin(II)‐ und Iridium(III)‐Komplexe von Bis[imidazol‐4‐yl]alkanen

Dinuclear Palladium(II), Platinum(II), and Iridium(III) Complexes of Bis[imidazol‐4‐yl]alkanes The reaction of bis(1,1′‐triphenylmethyl‐imidazol‐4‐yl) alkanes ((CH₂)_n bridged imidazoles L(CH₂)_nL, n = 3–6) with chloro bridged complexes [R₃P(Cl)M(μ‐Cl)M(Cl)PR₃] (M = Pd, Pt; R = Et, Pr, Bu) affords the dinuclear compounds [Cl₂(R₃P)M–L(CH₂)_nL–M(PR₃)Cl₂] 1 – 17 . The structures of [Cl₂(Et₃P)Pd–L(CH₂)₃L–Pd(PEt₃)Cl₂] ( 1 ), [Cl₂(Bu₃P)Pd–L(CH₂)₄L–Pd(PBu₃)Cl₂] ( 10 ), [Cl₂(Et₃P)Pd–L(CH₂)₅L–Pd(PEt₃)Cl₂] ( 3 ), [Cl₂(Et₃P)Pt–L(CH₂)₃L–Pt(PEt₃)Cl₂] ( 13 ) with trans Cl–M–Cl groups were determined by X‐ray diffraction. Similarly the complexes [Cl₂(Cp*)Ir–L(CH₂)_nL–Ir(Cp*)Cl₂] (n = 4–6) are obtained from [Cp*(Cl)Ir(μ‐Cl)₂Ir(Cl)Cp*] and the methylene bridged bis(imidazoles).     

Diimido‐, Imido(oxo)‐, Dioxo‐ und Imido(alkyliden)‐Halbsandwich‐Verbindungen über selektive Hydrolyse und α—H‐Abstraktion an Organylkomplexen des sechswertigen Molybdäns und Wolframs

Diimido, Imido Oxo, Dioxo, and Imido Alkylidene Halfsandwich Compounds via Selective Hydrolysis and α—H Abstraction in Molybdenum(VI) and Tungsten(VI) Organyl Complexes Organometal imides [(η⁵‐C₅R₅)M(NR′)₂Ph] (M = Mo, W, R = H, Me, R′ = Mes, tBu) 4 — 8 can be prepared by reaction of halfsandwich complexes [(η⁵‐C₅R₅)M(NR′)₂Cl] with phenyl lithium in good yields. Starting from phenyl complexes 4 — 8 as well as from previously described methyl compounds [(η⁵‐C₅Me₅)M(NtBu)₂Me] (M = Mo, W), reactions with aqueous HCl lead to imido(oxo) methyl and phenyl complexes [(η⁵‐C₅Me₅)M(NtBu)(O)(R)] M = Mo, R = Me ( 9 ), Ph ( 10 ); M = W, R = Ph ( 11 ) and dioxo complexes [(η⁵‐C₅Me₅)M(O)₂(CH₃)] M = Mo ( 12 ), M = W ( 13 ). Hydrolysis of organometal imides with conservation of M‐C σ and π bonds is in fact an attractive synthetic alternative for the synthesis of organometal oxides with respect to known strategies based on the oxidative decarbonylation of low valent alkyl CO and NO complexes. In a similar manner, protolysis of [(η⁵‐C₅H₅)W(NtBu)₂(CH₃)] and [(η⁵‐C₅Me₅)Mo(NtBu)₂(CH₃)] by HCl gas leads to [(η⁵‐C₅H₅)W(NtBu)Cl₂(CH₃)] 14 und [(η⁵‐C₅Me₅)Mo(NtBu)Cl₂(CH₃)] 15 with conservation of the M‐C bonds. The inert character of the relatively non‐polar M‐C σ bonds with respect to protolysis offers a strategy for the synthesis of methyl chloro complexes not accessible by partial methylation of [(η⁵‐C₅R₅)M(NR′)Cl₃] with MeLi. As pure substances only trimethyl compounds [(η⁵‐C₅R₅)M(NtBu)(CH₃)₃] 16 ‐ 18 , M = Mo, W, R = H, Me, are isolated. Imido(benzylidene) complexes [(η⁵‐C₅Me₅)M(NtBu)(CHPh)(CH₂Ph)] M = Mo ( 19 ), W ( 20 ) are generated by alkylation of [(η⁵‐C₅Me₅)M(NtBu)Cl₃] with PhCH₂MgCl via α‐H abstraction. Based on nmr data a trend of decreasing donor capability of the ligands [NtBu]^2— > [O]^2— > [CHR]^2— ? 2 [CH₃]^— > 2 [Cl]^— emerges.     

Sekundäre Hydroxyalkylphosphane: Synthese und Charakterisierung mono‐, bis‐ und trisalkoxyphosphan‐substituierter Zirconiumkomplexe und des heterobimetallischen Dreikernkomplexes [Cp2Zr{O(CH2)3PHMes(AuCl)}2]

Secondary Hydroxyalkylphosphanes: Synthesis and Characterization of Mono‐, Bis‐ and Trisalkoxyphosphane‐substituted Zirconium Complexes and the Heterobimetallic Trinuclear Complex [Cp₂Zr{O(CH₂)₃PHMes(AuCl)}₂] The secondary hydroxyalkylphosphanes RPHCH₂OH [R = 2,4,6‐Me₃C₆H₂ (Mes) ( 1 ), 2,4,6‐ⁱPr₃C₆H₂ (Tipp) ( 2 )], 1‐AdPH‐2‐OH‐cyclo‐C₆H₁₀ ( 3 ) and RPH(CH₂)₃OH [R = Ph ( 4 ), Mes ( 5 ), Tipp ( 6 ), Cy ( 7 ), ^tBu ( 8 )] were obtained from primary phosphanes RPH₂ and formaldehyde ( 1 , 2 ) or from LiPHR and cyclohexene oxide ( 3 ) or trimethylene oxide ( 4 ‐ 8 ). Starting from 5 or 7 and [Cp^R₂ZrMe₂] [Cp^R = C₅EtMe₄ (Cp°), C₅H₅ (Cp), C₅MeH₄ (Cp′)], the monoalkoxyphosphane‐substituted zirconocene complexes [Cp^R₂Zr(Me){O(CH₂)₃PHMes}] [Cp^R = Cp° ( 9 ), Cp ( 10 )] were prepared. With [Cp^R₂ZrCl₂], the bisalkoxyphosphane‐substituted complexes [Cp′₂Zr{O(CH₂)₃PHMes}₂] ( 11 ) and [Cp₂Zr{O(CH₂)₃PHCy}₂] ( 12 ) are obtained, and with [Tp^RZrCl₃], the trisalkoxyphosphane‐substituted zirconium complexes [Tp^RZr{O(CH₂)₃PHMes}₃] [Tp^R = trispyrazolylborato (Tp) ( 13 ), Tp^R = tris(3,5‐dimethyl)pyrazolylborato (Tp*) ( 14 )] are prepared. The reaction of 5 with [AuCl(tht)] (tht = tetrahydrothiophene) yielded the mononuclear complex [AuCl{PHMes(CH₂)₃OH}] ( 15 ). The trinuclear complex [Cp₂Zr{O(CH₂)₃PHMes(AuCl)}₂] ( 16 ) was obtained from [Cp₂ZrCl₂] and 15 . Compounds 1 ‐ 16 were characterized spectroscopically (¹H‐, ³¹P‐, ¹³C‐NMR; IR; MS) and compound 2 also by crystal structure determination. The bis‐ and trisalkoxyphosphane‐substituted complexes 11‐14 and 16 were obtained as mixtures of two diastereomers which could not be separated.     

Synthesis and Characterization of Secondary Nitrosamines from Secondary Amines Using Sodium Nitrite and p‐Toluenesulfonic Acid

We synthesized nitrosamines (R₂N? NO) with R=iPr ( 1 ), nPr ( 2 ), nBu ( 3 ), and hydroxyethyl ( 4 ) from the amine using sodium nitrite/p‐toluenesulfonic acid in CH₂Cl₂. The rate of formation of 1 – 4 increases in the direction iPr<nPr<nBu2CH₂OH. Compounds 1 – 3 were obtained as colorless solids, whereas 4 is a bright yellow liquid. Compounds 1 – 4 were characterized by elemental analysis, MS, IR, and multinuclear NMR (¹H, ¹³C, and ¹⁵N) spectroscopies. Additionally, we measured the UV/Vis spectra of all compounds, which show maxima of absorption at approximately 221 nm and molar extinction coefficients between 3043 and 4859 L mol^?1 cm^?1. We calculated the optimized structures of 1 – 4 (B3LYP/6‐311+G(d,p)) and computed the NMR spectroscopic chemical shifts and infrared frequencies. Furthermore, we carried out a natural bond orbital (NBO) analysis of the nitrosamine moiety. Lastly, the compounds described in this work are valuable starting materials for the synthesis of 2‐tetrazenes with potential interest to replace highly toxic hydrazines in rocket propulsion.     

Preparation and structures of a series of phosphorus‐free Nickel(II) diamine complexes and their applications in hydrogenation of acetophenone

To develop economical and phosphorus‐free catalysts for hydrogenation of ketones, three new complexes, [Ni(1R,2R‐dpen)₂(H₂O)Cl]₂Cl₂· 2Et₂O (1), [Ni(1R,2R‐dpen)(phen)(CH₃OH)₂]Cl₂·2CH₃OH (2) and [Ni(1,8‐dan)₂(DMF)Cl]₂Cl₂· 3H₂O (3), and three reported compounds, [Ni(opda)(phen)Cl₂]·CH₃OH (4), [Ni(opda)₂Cl₂] (5) and [Ni(1,2‐dach)₂]Cl₂ (6), were prepared and the structures of new compounds were determined by single crystal X‐ray diffraction analysis, in which 1R,2R‐dpen, phen, 1,8‐dan, opda and 1,2‐dach denote 1R,2R‐1,2‐diphenylethylenediamine, 1,10‐phenanthroline, 1,8‐diaminonaphthalene, o‐phenylenediamine and 1,2‐diaminocyclohexane, respectively. The catalytic effects for hydrogenation of acetophenone of these compounds were tested. This revealed very poor or no catalytic effects of these complexes in transfer hydrogenation of acetophenone using isopropanol or HCOOH? NEt₃ as hydrogen source. However, they presented much better catalytic effects in ionic hydrogenation of acetophenone using H₂ gas as hydrogen source with a dependence of the catalytic effects on the base used in the hydrogenation reactions. The complexes represent a kind of green hydrogenation catalyst, although the conversion in the hydrogenation reactions is not as high as expected. Copyright © 2010 John Wiley & Sons, Ltd.     

Binukleare Nickel(0)-Alkin-Koordinationsverbindungen – Zusammenhang zwischen Ligandperipherie und supramolekularer Struktur

Binuclear Nickel(0) Alkyne Coordination Compounds – Correlation between Ligand Periphery and Supramolecular Structure Reaction of Ni(cdt: 1,5,9-cyclododecatriene) with functionalized alkynes and subsequent reaction with ethylenediamines gives binuclear compounds of the type (diamine)Ni(μ-alkyne)Ni(alkyne). Compounds with alkyne-diols (N?N)Ni₂(HOR¹R²C? C?C? CR¹R²OH)₂ show supramolecular structures in which two identical intramolecular and one intermolecular hydrogen bonds are realized. 1 and 2 (chelate ligand in each case N,N,N′,N′-tetramethylethylenediamine, TMEDA, in 1 R¹ = R² = Me, in 2 R¹ = R² = Et) polymer-like chains are built up by connecting the binuclear units. Via two intermolecular hydrogen bonds per organometallic unit in 1 and via one intermoleculare hydrogen bond in 2 the chains are connected to give double chains. By substitution of one methyl group of TMEDA by hydrogen ( 3 : R¹ = R² = Me) a polymerlike network is produced by connecting the polymer-like chains. In compound 4 in which one of the methyl groups of TMEDA is substituted by CH₂CH₂NMe₂ the polymer-like chains remain unconnected. In 5 (diamine = TMEDA, alkyne = (CH₃)₃C? C?C? CMe₂OH) one intermolecular hydrogen bond per organometallic unit is observed forming again polymer-like chains that are independent of each other.     

Umsetzungen von Cp*NbCl4 und Cp*TaCl4 mit Trimethylsilyl‐azid,Me3Si‐N3. Molekülstrukturen der bis(azido)‐oxo‐verbrückten Komplexe [Cp*NbCl(N3)(μ‐N3)]2(μ‐O) und [Cp*TaCl2(μ‐N3)]2(μ‐O) (Cp* = Pentamethylcyclopentadienyl)

Reactions of Cp*NbCl₄ and Cp*TaCl₄ with Trimethylsilyl‐azide, Me₃Si‐N₃. Molecular Structures of the Bis(azido)‐Oxo‐Bridged Complexes [Cp*NbCl(N₃)(μ‐N₃)]₂(μ‐O) and [Cp*TaCl₂(μ‐N₃)]₂(μ‐O) (Cp* = Pentamethylcyclopentadienyl) The chloro ligands in Cp*TaCl₄ (1c) can be stepwise substituted for azido ligands by reactions with trimethylsilyl azide, Me₃Si‐N₃ (A) , to generate the complete series of the bis(azido)‐bridged dimers [Cp*TaCl_3‐n(N₃)_n(μ‐N₃)]₂ ( n = 0 (2c) , n = 1 (3c) , n = 2 (4c) and n = 3 (5c) ). If the solvent CH₂Cl₂ contains traces of water, an additional oxo bridge is incorporated to give [Cp*‐TaCl₂(μ‐N₃)]₂(μ‐O) (6c) or [Cp*TaCl(N₃)(μ‐N₃)]₂(μ‐O) (7c) , respectively. Both 6c and 7c are also formed in stoichiometric reactions from [Cp*TaCl₂(μ‐OH)]₂(μ‐O) (8c) and A . Analogous reactions of Cp*NbCl₄ (1b) with A were used to prepare the azide‐rich dinuclear products [Cp*NbCl_3‐n(N₃)_n(μ‐N₃)]₂ (n = 2 (4b) , and n = 3 (5b) ), and [Cp*NbCl(N₃)(μ‐N₃)]₂(μ‐O) (7b) . The mononuclear complex Cp*Ta(N₃)Me₃ (10c) is obtained from Cp*Ta(Cl)Me₃ and A . All azido complexes were characterised by their IR as well as their ¹H and ¹³C NMR spectra; X‐ray crystal structure analyses are available for 6c and 7b .     

Phosphanimin‐Komplexe des Berylliums und Phosphaniminato‐Komplexe mit Heterokubanstruktur

Phosphaneimine Complexes of Beryllium and Phosphoraneiminato Complexes with Heterocubane Structure Beryllium dichloride reacts with the silylated phosphaneimine Me₃SiNPEt₃ in dichloromethane solution to give the monomeric donor‐acceptor complex [BeCl₂(Me₃SiNPEt₃)] ( 1 ). Under cleavage of trimethylchlorosilane the thermolysis of 1 at 160 °C leads to the formation of the phosphoraneiminato complex [BeCl(μ₃‐NPEt₃)]₄ ( 2 ) with heterocubane structure. In the presence of BeCl₂ 1 reacts in the melt to give the phosphoraneiminato complex [Be₄Cl₄(μ₃‐Cl)(μ₃‐NPEt₃)₃] ( 3 ), the structure of which corresponds with the structure of 2 by substitution of a ligand (μ₃‐NPEt₃)^— by a μ₃‐chloro ligand. As a by‐product from the synthesis of 2 in dichloromethane solution the phosphaneimine complex [BeCl₂(μ‐HNPEt₃)]₂·CH₂Cl₂ ( 4 ·CH₂Cl₂) can be obtained. Its dimeric units form dimers [{BeCl₂(μ‐HNPEt₃)}₂]₂ with symmetry D₂ via Cl···H‐N hydrogen bridges. The compounds 1 — 4 ·CH₂Cl₂ are characterized by X‐ray structure determinations, 1 — 3 additionally by IR spectroscopy. 1 : Space group C2/c, Z = 8, lattice dimensions at 193 K: a = 1502.5(1), b = 801.8(1), c = 2609.6(2) pm, β = 96.15(1)°, R₁ = 0.0523. 2 : Space group C2/c, Z = 4, lattice dimensions at 193 K: a = 1992.2(2), b = 1054.8(1), c = 1950.6(2) pm, β = 114.82(1)°, R₁ = 0.0275. 3 : Space group P2₁2₁2₁, Z = 4, lattice dimensions at 193 K: a = 1159.5(1), b = 1199.0(1), c = 2251.1(2) pm, R₁ = 0.0399. 4 ·CH₂Cl₂: Space group Ccca, Z = 8, lattice dimensions at 193 K: a = 1454.6(1), b = 2795.7(3), c = 1235.6(1) pm, R₁ = 0.0349.     

Metallkomplexe mit biologisch wichtigen Liganden. CLVII [1] Halbsandwich‐Komplexe mit Isocyanoacetylaminosäureestern und Isocyanoacetyldi‐ und tripeptidestern („Isocyano‐Peptide”︁)

Metal Complexes of Biologically Important Ligands, CLVII [1] Halfsandwich Complexes of Isocyanoacetylamino acid esters and of Isocyanoacetyldi‐ and tripeptide esters (?Isocyanopeptides”?) N‐Isocyanoacetyl‐amino acid esters CNCH₂C(O) NHCH(R)CO₂CH₃ (R = CH₃, CH(CH₃)₂, CH₂CH(CH₃)₂, CH₂C₆H₅) and N‐isocyanoacetyl‐di‐ and tripeptide esters CNCH₂C(O)NHCH(R¹)C(O)NHCH(R²)CO₂C₂H₅ and CNCH₂C(O)NHCH(R¹)C(O)NHCH (R²)C(O)NHCH(R³)CO₂CH₃ (R¹ = R² = R³ = CH₂C₆H₅, R² = H, CH₂C₆H₅) are available by condensation of potassium isocyanoacetate with amino acid esters or peptide esters. These isocyanides form with chloro‐bridged complexes [(arene)M(Cl)(μ‐Cl)]₂ (arene = Cp*, p‐cymene, M = Ir, Rh, Ru) in the presence of Ag[BF₄] or Ag[CF₃SO₃] the cationic halfsandwich complexes [(arene)M(isocyanide)₃]⁺X^? (X = BF₄, CF₃SO₃).     

A Series of [Mn6] Complexes with Terminal Functional Groups

A series of [Mn₆O₂(R¹OH)₄(sao)₆(R²COO)₂] complexes with terminal functional groups ( 1 : R¹ = CH₃, R² = HO‐C₆H₄, 2 : R¹ = C₂H₅, R² = H₂N‐C₆H₄, 3 : R¹ = CH₃, R² = Cl‐C₆H₄, 4 : R¹ = CH₃, R² = CH₃S‐C₆H₄, 5 : R¹ = CH₃, R² = I‐C₆H₄, 6 : R¹ = CH₃, R² = pymSCH₂, 7 : R¹ = CH₃, R² = ortho‐pyr‐SCH₃, 8 : R¹ = C₂H₅, R² = (CH₃)₃OOCNHCH₂C₆H₄; sao = doubly deprotonated salicylaldoxime ligand, pym = pyrimidyl, pyr = pyridyl) have been obtained in a reaction of a ligand R²C₆H₄COOH, salicylaldoxime, manganese(II) perchlorate and [NEt₄](OH) in methanol or a 1:1 mixture of ethanol and dichloromethane. In this report, structural aspects as well as preliminary studies of magnetic and thermal properties are presented. Compounds 1 , 3 , 6 , 8 exhibit an antiferromagnetic coupling of the Mn²⁺ ions, whereas 4 and 7 show ferromagnetic interactions. The title compounds may act as starting materials for further derivatization addressing the functional groups.     

Cyclopentadienyl Dicarbonyl Iron‐Bismuth Compounds – Synthesis,Structure, and Reactivity

Abstract. The cyclopentadienyl‐substituted iron‐bismuth complexes [{Cp(CO)₂Fe}BiCl₂] ( 1 ), [{Cp(CO)₂Fe}BiBr₂] ( 2 ), [{Cp′′(CO)₂Fe}BiBr₂] ( 3 ) and [{Cp*(CO)₂Fe}BiBr₂] ( 4 ) were prepared with high yields starting from [Cp^x(CO)₂Fe]₂ [Cp^x = C₅H₅ (Cp), C₅H₃‐1, 3‐tBu₂ (Cp′′), C₅Me₅ (Cp*)] and the corresponding bismuth halides. The single crystal X‐ray structure analyses of compounds 2 – 4 are reported. Comparison of their solubility demonstrates that the steric hindrance in this type of compounds is only slightly higher for compound 3 compared with compound 2 but significantly lower compared with the Cp* derivative 4 . Compounds 1 – 4 react with nucleophililic reagents such as KOtBu, NaOCH₂CH₂OCH₃, and NaOSiMe₃ as well as with water in the presence of an amine to give a mixture of [{Cp^x(CO)₂Fe}BiX] (X = Cl, Br) and [{Cp^x(CO)₂Fe}₃Bi]. In case of a reaction with nBu₄NCl and DMAP (dimethylaminopyridine) no such dismutation is observed. Instead the complexes [{Cp(CO)₂Fe}BiBr₂(DMAP)₂] ( 5 ), [NnBu₄]₂[{{Cp(CO)₂Fe}BiBr₃}₂] ( 6 ) and [NnBu₄]₂[{{Cp(CO)₂Fe}BiCl₃}₂] ( 7 ) were isolated and characterized by single‐crystal X‐ray diffraction.     

Synthesis,electrochemical properties and fungicidal activity of 1,1′‐bis(aroyl)ferrocenes and their derivatives

Reaction of functionalized cyclopentadienyl sodium CH₃O₂CArC(O)CpNa (Ar = aryl and Cp = cyclopentadienyl) with FeCl₂ in a 2:1 ratio gives 1,1′‐bis(aroyl)ferrocenes [CH₃O₂CArC(O)Cp]₂Fe in reasonable yields. Upon treatment of these aroyl compounds with NaBH₄, the ketone carbonyl is reduced to yield compounds [CH₃O₂CArCH(OH)Cp]₂Fe, while with the stronger reductive reagent LiAlH₄, diols [HOCH₂ArCH(OH)Cp]₂Fe are obtained. All new compounds were characterized by IR and NMR spectroscopic analyses. Their electrochemical behavior was investigated by cyclic voltammetry. The structure of [CH₃O₂CC₁₀H₆C(O)Cp]₂Fe was further confirmed by single crystal X‐ray diffraction analysis. In addition, the fungicidal activities of these new compounds were also determined in vitro. Copyright © 2007 John Wiley & Sons, Ltd.     

Palladium(II)‐ und Platin(II)‐Komplexe mit dem Antimalariamittel Mefloquin als Liganden

Metal Complexes of Biologically Important Ligands. CXXVI. Palladium(II) and Platinum(II) Complexes with the Antimalarial Drug Mefloquine as Ligand The coordination sites of the antimalarial drug mefloquine (L) were studied. Reactions of the chloro bridged complexes (allyl)Pd(μ‐Cl)₂Pd(allyl) and (R₃P)(Cl)M(μ‐Cl)₂M(Cl)(PR₃) (M = Pd, Pt) with racemic mefloquine give the compounds (allyl)(Cl)Pd(L) ( 1 ), Cl₂(Et₃P)Pt(L) ( 2 ) and Cl₂(Et₃P)Pd(L) ( 3 ) with coordination of the piperidine N atom of mefloquine. In the presence of NaOMe the N,O‐chelate complexes Cl(Et₃P)Pt(L–H⁺) ( 4 ) and Cl(R₃P)Pd(L–H⁺) ( 5 , 6 , R = Et, nBu) were obtained. Protection of the piperidine N atom of mefloquine by protonation allows the synthesis of the complexes Cl₂(Et₃P)Pt(L + H⁺) ( 7 ) in which mefloquine is coordinated via the quinoline N atom. The structures of 2 , 3 and 4 were determined by X‐ray diffraction analysis. In the crystal of 4 pairs of enantiomers are found which are linked by two hydrogen bridges between the amine group and the chloro ligand.     

Fluoro-olefin chemistry Part 20 [1]. Reaction of hexafluoropropene with alcohols

Reaction of hexafluoropropene (HFP) with a series of alcohols under thermal, photochemical or peroxide-initiated conditions affords the 1:1 adducts CF₃CHFCF₂CR¹R²OH (R¹ = H, R² = H, Me, Prⁿ or CF₃; R¹ = Me, R² = Me or Et) in high yield via a radical chain mechanism. Adduct are not formed with the alcohols (CF₃)₂CHOH and CF₃CHFCF₂CH₂OH. Other 1:1 adducts of structure CHF₂CF(CF₃)CH₂OH and CH₃(C₂H₃CF₂CHFCF₃)CH₂OH are formed as minor products in the methanol and $\text{n}$-butanol reactions, respectively.     

Synthesis and Characterization of Two Novel Complexes of Cr(III) with Benzilmonoxime

The reaction of benzilmonoxime (BMOH) with CrCl₃.6H₂O in methanol gives the mono nuclear Cr(III) complex, [Cr(BMO)3₃ ( 1 ). Reaction of complex 1 with a methanolic solution of KOH at room temperature leads to a di‐nuclear Cr(III)‐Cr(III) complex, [Cr(BMO)₂(OH)]₂ ( 2 ). The complexes were characterized on the basis of their elemental analysis, Mass, IR, ¹H and ¹³C‐NMR and electronic spectra. The IR studies were useful in assigning the coordination mode of the benzilmonoxime ligand to the chromium(III) ion. In addition, the presence of a hydroxo bridge in the dimeric complex 2 is inferred from the IR spectral studies. The electronic spectra of the complexes revealed two bands due to d–d transitions, and one band assignable to an oxygen (p_π)→Cr(eg*) LMCT transition observed in both complexes. An additional charge transfer transition, assignable to μ‐OH(p_π)→Cr(eg*), was only observed for the dimeric complex 2 . The splitting energy and Racah parameter were calculated to be 18484 cm^‐1 and 560 cm^‐1 for [Cr(BMO)₃] ( 1 ), 17986 cm^‐1 and 545 cm^‐1 for [Cr(BMO)₂(OH)]₂ ( 2 ) respectively.     

New Heteronuclear Bridged Borylene Complexes That Were Derived from [{Cp*CoCl}2] and Mono‐Metal?Carbonyl Fragments

The synthesis, structural characterization, and reactivity of new bridged borylene complexes are reported. The reaction of [{Cp*CoCl}₂] with LiBH₄ ? THF at ?70 °C, followed by treatment with [M(CO)₃(MeCN)₃] (M=W, Mo, and Cr) under mild conditions, yielded heteronuclear triply bridged borylene complexes, [(μ₃‐BH)(Cp*Co)₂(μ‐CO)M(CO)₅] ( 1 – 3 ; 1 : M=W, 2 : M=Mo, 3 : M=Cr). During the syntheses of complexes 1 – 3 , capped‐octahedral cluster [(Cp*Co)₂(μ‐H)(BH)₄{Co(CO)₂}] ( 4 ) was also isolated in good yield. Complexes 1 – 3 are isoelectronic and isostructural to [(μ₃‐BH)(Cp*RuCO)₂(μ‐CO){Fe(CO)₃}] ( 5 ) and [(μ₃‐BH)(Cp*RuCO)₂(μ‐H)(μ‐CO){Mn(CO)₃}] ( 6 ), with a trigonal‐pyramidal geometry in which the μ₃‐BH ligand occupies the apical vertex. To test the reactivity of these borylene complexes towards bis‐phosphine ligands, the room‐temperature photolysis of complexes 1 – 3 , 5 , 6 , and [{(μ₃‐BH)(Cp*Ru)Fe(CO)₃}₂(μ‐CO)] ( 7 ) was carried out. Most of these complexes led to decomposition, although photolysis of complex 7 with [Ph₂P(CH₂)_nPPh₂] (n=1–3) yielded complexes 9 – 11 , [3,4‐(Ph₂P(CH₂)_nPPh₂)‐closo‐1,2,3,4‐Ru₂Fe₂(BH)₂] ( 9 : n=1, 10 : n=2, 11 : n=3). Quantum‐chemical calculations by using DFT methods were carried out on compounds 1 – 3 and 9 – 11 and showed reasonable agreement with the experimentally obtained structural parameters, that is, large HOMO–LUMO gaps, in accordance with the high stabilities of these complexes, and NMR chemical shifts that accurately reflected the experimentally observed resonances. All of the new compounds were characterized in solution by using mass spectrometry, IR spectroscopy, and ¹H, ¹³C, and ¹¹B NMR spectroscopy and their structural types were unequivocally established by crystallographic analysis of complexes 1 , 2 , 4 , 9 , and 10 .     

Bildung siliciumorganischer Verbindungen. 102. Zur Umsetzung von Chlormethanen mit elementarem Silicium (Bildung und Aufklärung linearer Carbosilane)

Formation of Organosilicon Compounds. 102. Reaction of Chlormethanes with Elemental Silicon. (Formation and Investigation of Linear Carbosilanes) Reactions of CH₂Cl₂, HCCl₃ and CCl₄ with silicon (Cu catalyst) in a fluid bed at about 320°C were carried out to investigate especially the Si-rich compounds. In the reactions of CH₂Cl₂ and CHCl₃, but not of CCl₄, in addition to already published compounds Si-rich viscous products are formed. The SiCl-containing mixtures were reacted with LiAlH₄, and the SiH-containing derivatives were separated by means of HPLC. CH₂Cl₂/Si forms unbranched chains of carbosilanes as Si_nC_n–1H_4n (n = 4—12,2 terminal SiH₃ groups) and Si_nC_nH_4n+2 (n = 4—9, 1 terminal SiH₃ and 1 CH₃ group) as well as 1,3,5-trisilacyclohexanes with carbosilane chains of various length attached either to a Si atom or to a C atom. CHCl₃/Si yields in addition to unbranched chains with terminal silyl group chains with one or two C-branches and 1,3,5-trisilacyclohexanes with 1, 2, or 3 silyl substituents attached to C atoms. The structure of the isolated compounds was investigated by nmr and mass spectrometry.     

Isomerization,Ring Expansion,and Ring Contraction of 1,3‐Diphosphete Complexes

Reactions between the 1,3‐diphosphete complex [Cp′′′Co(η⁴‐P₂C₂tBu₂)] ( 1 ) and Ag[Al{OC(CF₃)₃}₄] (Ag[pftb]) were carried out under different conditions. In CH₂Cl₂, the unprecedented 1,2‐diphosphete isomerization product [Ag₂{Cp′′′Co(μ,η⁴:η¹:η¹‐1,2‐P₂C₂tBu₂)}₂{Cp′′′Co(μ,η⁴:η¹‐1,2‐P₂C₂tBu₂)}₂]⋅2[pftb] ( 2 ) could be isolated. In diffusion experiments of 1 in n‐hexane with Ag[pftb] in CH₂Cl₂, the triphosphacobaltocenium complex [Cp′′′Co(η⁵‐P₃C₂tBu₂)][pftb] ( 4 ) and the phosphirenylium complex [Cp′′′Co(η³‐PC₂tBu₂)][pftb] ( 5 ) were obtained, showing a ring expansion and a ring contraction, respectively, under mild conditions. Moreover, addition of pyridine to the Ag complex 2 led to the new 1,2‐diphosphete complex [Cp′′′Co(η⁴‐1,2‐P₂C₂tBu₂)] ( 3 ). Compound 3 is also formed by thermolysis of 1 , making it a promising method for this type of isomerization. 1,2‐Diphosphete complexes like 3 are thermodynamically more stable but also synthetically more elusive than their 1,3‐isomer counterparts.     

Synthesis,Properties, and Structures of Chromium(VI) and Chromium(V) Complexes with Heterocyclic Nitrogen Ligands

The reaction of CrO₂Cl₂ with 2, 2′‐bipyridyl or 1, 10‐phenanthroline (diimine) in CCl₄ or anhydrous CH₃CO₂H solution, produces orange‐brown diamagnetic [CrO₂Cl₂(diimine)]. The X‐ray structure of [CrO₂Cl₂(2, 2′‐bipy)] shows a six‐coordinate central chromium(VI) atom with cis‐dioxo groups trans to the diimine. In contrast, the diimines react with CrO₃ in CH₃CO₂H / conc. aqueous HCl to form bright red paramagnetic Cr^V complexes, [CrOCl₃(diimine)]. The X‐ray structure of [CrOCl₃(2, 2′‐bipy)] shows a six‐coordinate central chromium atom with mer‐chlorines and the diimine trans to O/Cl. The addition of [2, 2‐bipyH₂]Cl₂ to a solution of CrO₃ in CH₃CO₂H saturated with HCl gas, produces the Cr^V anion [2, 2′‐bipyH₂][CrOCl₄]Cl, which loses HCl on heating in vacuo to form [CrOCl₃(2, 2′‐bipy)]. IR, UV/Vis, and ¹H NMR spectra (Cr^VI only) are reported for the new complexes. Attempts to extend these routes to oxygen donor ligands, including ethers and phosphine oxides, were unsuccessful. The diimine complexes are the first structurally autheticated adducts of chromium(VI) and (V) oxide‐chlorides with neutral ligands.     

Nickel(II)‐Komplexe von Oxalamidinen und Oxalamidinaten mit zusätzlichen R2P‐Donorgruppen

Complexes of Nickel(II) with Oxalic Amidines and Oxalic Amidinates with Additonal R₂P‐Donor Groups Oxalamidines R¹N=C(NHR²)‐C(=NHR²)=NR¹, which bear additional donor atoms at two of the four N substituents ( H₂A : R¹ = mesityl, R² = ‐(CH₂)₃‐PPh_2; H₂B : R¹ = tolyl, R² = ‐(CH₂)₃‐PMe₂) form binuclear complexes with Nickel(II) in which very different coordination modes are realized. In the complex [ (A) Ni₂Br₂] (1) the two nickel atoms at each side of the bridge are in a square‐planar environment, coordinated by the two N donor atoms of the oxalic amidinate framework, a bromide and a Ph₂P group. An analogous coordination has the organometallic compound [ (A) Ni₂Me₂] (2) . In contrast, the two nickel atoms in the compound {[( B )][Ni(acac)]₂} (5) differ in their coordinative environment. At one side of the oxalic amidinate bridging ligand a (acac)Ni fragment is coordinated by the two N donor atoms resulting in a square‐planar environment. At the opposite side the (acac)Ni fragment is coordinated at the both N donor ligands of the bridging ligand as well as at the two PMe₂ groups of the side chains resulting in an octahedral coordination for this nickel atom.