Promoting effect of ionic liquids on ligand substitution reactions

Ionic liquid solvents N-hexylpyridinium bistrifylimide ([C₆pyr][Tf₂N]] and 1-butyl-3-methylimidazolium hexafluorophosphate ([C₄mim][PF₆]) promoted the displacement of anionic ligands by pyridine derivatives in trans-(Ph₃P)₂Rh(CO)NO₃ to a much greater extent than did dichloromethane. Thus, addition of a slight excess of 2-fluoropyridine to trans-(Ph₃P)₂Rh(CO)NO₃ in [C₄mim][PF₆] gave a 29:71 product mixture of trans-(Ph₃P)₂Rh(CO)NO₃:[trans-(Ph₃P)₂Rh(CO)(2-fluoropyridine)][NO₃], while the ratio was 91:9 in dichloromethane.     

Vanadaphospha-alkanes and -cycloalkanes prepared by photoreaction of carbonyl-vanadium compounds with tetraphenyldiphosphines

Reaction between Ph₂PPPh₂ and [Et₄N] [V(CO)₆] yields cis-[Et₄N]₂-[(μ-Ph₂PPPh₂)₂{V(CO)₄}₂], which may have a cyclic structure, and [Et₄N]₂-[(μ-Ph₂PPPh₂){V(CO)₅}₂]. An “open-chain”, monometallic species [η⁵-CpV(CO)₃-Ph₂PPPh₂] is formed with [η⁵-CpV(CO)₄]. Proposed structures are based on IR, ³¹P, and ⁵¹V NMR spectra.     

Use of phosphine gold acetylides [(R3P)AuCCR] to form phosphine gold derivatives of tetra-iron and penta-iron clusters

Five new gold acetylides, [AuCCR], with hydroxyl or amino functions in the organic radical R have been prepared. From these, nine phosphine complexes [(R₃P)AuCCR] with R = Ph or Cy were synthesised. Reactions between the phosphine gold acetylides [(Ph₃P)AuCCC(Me)(OH)Et] or [(Cy₃P)AuCCC(Me)(OH)Et] and the iron carbonyl cluster [Et₄N][Fe₄N(CO)₁₂] gave both neutral [(R₃P)AuFe₄N(CO)₁₂] and ionic compounds [(R₃P)₂Au][Fe₄N(CO)₁₂]. Reaction with the penta-iron cluster [Et₄N][Fe₅N(CO)₁₄] afforded [(R₃P)₂Au][Fe₅N(CO)₁₄], [(R₃P)₂Au][Fe₄N(CO)₁₂] and [(R₃P)AuFe₄N(CO)₁₂]. The gold-iron clusters were characterised with spectroscopic methods (IR, NMR and Mössbauer) and in the case of [(Cy₃P)AuFe₄N(CO)₁₂] a single-crystal X-ray analysis.     

Chemie der carbonylniobverbindungen: X. Neue hydridocarbonylkomplexe des vanadiums,niobs und tantals

Complexes of the general formula HM(CO)_n(oligophos) (M = V, n = 2; M = Nb, n = 3 and 2; M = Ta, n = 3) have been prepared by ion exchange on silica gel from their ionic precursors [Et₄N][M(CO)_4,3(oligophos)] (n = 3) or by UV irradiation of HM(CO)_n+1(oligophos) (n = 2). The new compounds, including fac-[Et₄N]-[Nb(CO)₃PPh(CH₂CH₂PPh₂)₂] and cis-[Et₄N][Ta(CO)₄PPh(CH₂CH₂PPh₂)₂], are characterized by their IR (ν(CO)), ¹H (hydride), ³¹P and metal (⁵¹V and ⁹³Nb) NMR spectra.     

Carbonylniobium chemistry : III. Tricarbonyl-η-cyclopentadienylhydridoniobate(−I): Preparation and Nb NMR spectroscopic invesitgation of [Et4N][CpNb(H)(CO)3] and [Et4N][CpNb(D)(CO)3]

The complexes [Et₄N][CpNb(X)(CO)₃] (X = H, D) have been prepared by reduction of CpNb(CO)₄ in THF and subsequent treatment with CX₃CN/[Et₄N]Cl. There is IR-spectroscopic evidence for the formation of an intermediate [CpNb(CO)₃]²⁻. The isotope effect (¹H, ²H) on the ⁹³Nb shielding (6 ppm) and the temperature dependencies of δ(⁹³Nb) (0.25 ppm/deg) and the line widths are discussed.     

Carbonylvanadium complexes of the tripod ligands MeC(CH2PPh2)3 and P(CH2CH2PPh2)3

UV irradiation of [Et₄N] [V(CO)₆] in the presence of the tripod ligands (L) MeC(CH₂PPh₂)₃ (cp₃) and P(CH₂CH₂PPh₂)₃ (pp₃) yields [Et₄N] [V(CO)₅L], cis-[Et₄N] [V(CO)₄L] and mer-[Et₄N] [V(CO)₃L] (where the meridional configuration for L = cp₃ is uncertain). Except for [Et₄N] [V(CO)₅cp₃], all these species were isolated. The complexes are characterized by their IR, ³¹P and ⁵¹V NMR spectra.     

The electronic structure of iron carbonyl complexes as probed by X-ray emission spectroscopy and quantum-chemical calculations

The electronic structure of the polynuclear iron carbonyl complexes [Et₂N][Fe₄N(CO)₁₂], [Et₄N]₂[Fe₅C(CO)₁₄], and [Et₄N]₂[Fe₆C(CO)₁₆] has been studied by X-ray emission spectroscopy and quantum-chemical calculations. The fine structure of the FeKβ₅ X-ray emission spectra characterizes the distribution of iron valence p electrons over the molecular orbitals of the compounds. Comparison of the fine structure of the FeKβ₅ X-ray emission spectra with the densities of states of all atoms in the molecules has made it possible to determine in detail the character and specific features of chemical bonding in the complexes.     

The seven-coordinate hydrido-tantalum complexes [Ta(H)(CO)6−n(oligophos)]: preparation and dynamics

The hydrido complexes cis-[HTa(CO)₄P₂] (P₂  Ph₂PCH₂CH₂PPh₂), HTa-(CO)₃P_m (P_m  P₃: PhP(CH₂CH₂PPh₂)₂, P₄: [Ph₂PCH₂CH₂PPhCH₂]₂, PP₃: P(CH₂CH₂PPh₂)₃) have been obtained from the photo-chemically produced complexes [Et₄N][Ta(CO)₄P_m] by ion-exchange chromatography on silica gel. The anionic and neutral complexes have been characterized by IR and ³¹P and ¹H NMR spectroscopy. The temperature-dependent ¹H(hydride)-³¹P NMR coupling patterns are interpreted in terms of a hydride-capped octahedral structure with restricted migration of the H⁻ ligand between the octahedral faces.     

Ethynylmonocarba-closo-dodecaborates: M[12-HCC-closo-1-CB11H11] and M[7,12-(HCC)2-closo-1-CB11H10] (M = Cs, [Et4N])

Cesium and tetraethylammonium salts of the ethynyl functionalized monocarba-closo-dodecaborate anions [12-HCC-closo-1-CB₁₁H₁₁]⁻ and [7,12-(HCC)₂-closo-1-CB₁₁H₁₀]⁻ were obtained by desilylation of [Et₄N][12-Me₃SiCC-closo-1-CB₁₁H₁₁] and [Et₄N][7,12-(Me₃SiCC)₂-closo-1-CB₁₁H₁₀], respectively. Their thermal properties were examined by differential scanning calorimetry. The compounds were characterized by multi-NMR, IR, and Raman spectroscopy, (−)-MALDI mass spectrometry, and elemental analysis. Single-crystals of Cs[12-HCC-closo-1-CB₁₁H₁₁] and [Et₄N][7,12-(HCC)₂-closo-1-CB₁₁H₁₀] were studied by X-ray diffraction. The discussion of the spectroscopic and structural properties is supported by data derived from theoretical calculations using density functional theory as well as perturbation theory.     

Syntheses, structures and intermolecular interactions of tetraorganoammonium, -phosphonium and -stibonium dimethyl- and diphenyltetrahaloantimonates

The syntheses and spectroscopic (NMR, MS) investigations of the antimonates [Ph₄P]⁺[Me₂SbCl₄]⁻ (1), [Me₄Sb]⁺[Me₂SbCl₄]⁻ (2), [Et₄N]⁺[Ph₂SbCl₄]⁻ (3), [Bu₄N]⁺[Ph₂SbCl₄]⁻ (4), [Me₄Sb]⁺[Ph₂SbCl₄]⁻ (5), [Et₃MeSb]⁺[Ph₂SbCl₄]⁻ (6), [Et₄N]⁺[Ph₂SbF₄]⁻ (7) and [Et₄N]⁺[Ph₂SbBr₄]⁻ (8) are reported. Halogen scrambling reactions of Et₄NBr or Ph₄EBr (E = P, Sb) with R₂SbCl₃ (R = Me, Ph) produce mixtures of compounds from which crystals of [Et₄N]⁺[Ph₂SbBr_1.24Cl_2.76]⁻ (9), [Et₄N]⁺[Ph₂SbBr_2.92Cl_1.08]⁻ (10) or [Ph₄Sb]⁺[Me₂SbCl₄]⁻ (11) were isolated. The crystal and molecular structures of 1 and 3-11 are reported.     

Reaction of [M(CO)4] (M = Ir, Rh) with cyclopropenyl tetrafluoroborate - Ring opening and coupling of cyclopropenyl ligands to form dinuclear metal complexes

Reaction of the iridium tetracarbonylate [PPN][Ir(CO)₄] (1a) with triphenylcyclopropenyl tetrafluoroborate [C₃Ph₃][BF₄] afforded two dinuclear species Ir₂(CO)₄(μ,η¹:η²-C₃Ph₃)(μ,η²:η³-C₃Ph₃) (2) and Ir₂(CO)₄(μ,η⁴:η⁴-C₆Ph₆) (3a) resulting from the ring opening and in the latter case, coupling of the resulting acyclic, propenyl ligands. The analogous reaction with [PPN][Rh(CO)₄] (1b) afforded only the rhodium analogue for 3a.     

Syntheses and X-ray structures of two nitrosyliron clusters [(Ph3P)2N] [Fe6C(CO)15NO] and (Fe6C(CO)11(NO)4]. First example of a carbonyl-nitrosyl cluster with four no ligands

[X]₂[Fe₆C(CO)₁₆] (X = (Ph₃P)₂N or Et₄N) reacts with NOBF₄ in CH₂Cl₂ to give [X] [Fe₆C(CO)₁₅NO]. This complex reacts with an excess of NOBF₄ to give [Fe₆C(CO)₁₁ (NO)₄]. The structures of the two new complexes were determined by X-ray crystallography.     

Synthesis and X-ray crystal structure of trans-[MoF(CCH2 tBu)(Ph2PCH2CH2PPh2)2][BF4], a paramagnetic alkylidynefluorocomplex

Treatment of the alkynylhydridocomplex [MoH₃(CC^tBu)(dppe)₂](dppePh₂PCH₂CH₂PPh₂) with [Et₂OH][BF₄] gives trans-[MoF(CCH₂^tBu)(dppe)₂], the first example of a stable paramagnetic alkylidyne complex, the X-ray structure of which is reported.     

Cumulated double bond systems as ligands : IV. 1H and 13C NMR studies of the intra- and inter-molecular exchange processes of cationic dialkylsulfurdiimine compounds of RhI,IrI and PtII

The preparation and properties are described of trans-[(Ph₃P)₂(CO)M(RNSNR)] [ClO₄] (M  Rh^I, Ir^I; R  Me, Et, i-Pr, t-Bu) and of cis- or trans-[L₂Pt(RNSNR)X] [ClO₄] (X  Cl^?, L  Et₂S, PhMe₂As, PhMe₂P, R  Me, t-Bu; X  CH₃, L  PhMe₂P, R  Me).¹H and ¹³C NMR data show the existence of various isomers in solution which may interconvert via intra- and inter-molecular exchange processes. A general reaction scheme for the intramolecular exchange processes is discussed.     

Zur Strukturchemie der Alkyl- und Arylhalogenoarsenate(III), [Me2As2Cl5]–, [RAsCl3]–, [R2As2Br6]2– (R = Me,Et, Ph) und [Ph2AsX2]– (X = Cl,Br)

Structural Chemistry of the Alkyl- and Arylhaloarsenates(III) [Me₂As₂Cl₅]^–, [RAsCl₃]^–, [R₂As₂Br₆]^2– (R = Me, Et, Ph) and [Ph₂AsX₂]^– (X = Cl, Br) The alkyl- and arylhaloarsenates(III) [Ph₄P][Me₂As₂Cl₅] ( 1 ), [Ph₄P][RAsCl₃] (R = Me, Et, Ph, 2 – 4 ), [Me₃PhN][PhAsCl₃] ( 5 ), [Ph₄P]₂[R₂As₂Br₆] (R = Me, Et, Ph, 6 – 8 ), [n-Pr₄N][Ph₂AsCl₂] ( 9 ) and [n-Bu₄N][Ph₂AsBr₂] ( 10 ) have been prepared and their structures established by X-ray diffraction. In contrast to the chloroarsenates(III) 2 – 5 , which all contain isolated ψ-trigonal bipyramidal anions [RAsCl₃]^–, the analogous bromoarsenates(III) 6 – 8 exhibit dimeric structures. Whereas the trans sited As–Cl distances in 2 and 3 are very similar a pronounced degree of asymmetry is apparent for the Cl–As–Cl three-centre bonds in 4 and 5 [2.396(1) and 2.602(1) Å in 5]. In 6 and 7 C_i symmetry related RAsBr₂ units are connected through long As…Br bonds [2.926(1) and 3.116(2) Å in 6 ]. The bromophenylarsenate(III) anion of 8 which contains two effectively undistorted ψ-trigonal bipyramids [PhAsBr₃]^– associated by weak As…Br interactions [3.117(2) Å]. In view of its very long bridging As…Cl distances the [Me₂As₂Cl₅]^– anion in 1 can, as 6 an 7 , be regarded as two MeAsCl₂ molecules weakly linked through a chloride ion.     

Anionic Gold(I) Complexes—Twelve‐ and Ten‐Vertex Monocarba‐closo‐borate Anions with Carbon–Gold σ Bonds

The anionic gold(I) complexes [1‐(Ph₃PAu)‐closo‐1‐CB₁₁H₁₁]^? ( 1 ), [1‐(Ph₃PAu)‐closo‐1‐CB₉H₉]^? ( 2 ), and [2‐(Ph₃PAu)‐closo‐2‐CB₉H₉]^? ( 3 ) with gold–carbon 2c–2e σ bonds have been prepared from [AuCl(PPh₃)] and the respective carba‐closo‐borate dianion. The anions have been isolated as their Cs⁺ salts and the corresponding [Et₄N]⁺ salts were obtained by salt metathesis reactions. The salt Cs‐ 3 isomerizes in the solid state and in solution at elevated temperatures to Cs‐ 2 with ΔH_iso=(?75±5) kJ mol^?1 (solid state) and ΔH^≠=(118±10) kJ mol^?1 (solution). The compounds were characterized by vibrational and multi‐NMR spectroscopies, mass spectrometry, elemental analysis, and differential scanning calorimetry. The crystal structures of [Et₄N]‐ 1 , [Et₄N]‐ 2 , and [Et₄N]‐ 3 were determined. The bonding parameters, NMR chemical shifts, and the isomerization enthalpy of Cs‐ 3 to Cs‐ 2 are compared to theoretical data.     

Überführung eines carben- in einen isocyanid-komplex

Pentacarbonyl(diphenylcarbene)tungsten, (CO)₅WCPh₂ (I), reacts with diethylamino(dimethyl)acetonitrile, Me₂(Et₂N)CCN (II), to give pentacarbonyl(diphenylmethylisocyanide)tungsten, (CO)₅W[CNC(H)Ph₂] (III). In the reaction of I with diethylaminoacetonitrile, H₂(Et₂N)CCN, and dimethylamino(methoxy)acetonitrile, H(MeO)(Me₂N)CCN, respectively, complex III is also formed in small amounts.     

Indium-based liquid clathrates. III. Inclusion compounds derived from [Bu4N][InCl3X] salts and their suitability as a catalysis medium

Tetrabutylammonium salts of the mixed haloindates, [Bu₄N][InCl₃X], X=Cl, Br, I, interact with aromatic solvents forming liquid inclusion compounds. The aromatic/cation ratio (A/C), a measure of the amount of guest aromatic, has been determined for a variety of simple aromatics. The values range from 2.6 to 0.4, substantially lower than the A/A of similar [Bu₄N][Al₂R₆X] liquid clathrates. The ability of these liquid clathrates to function as catalysis media has been explored. The solubility of (Ph₃P)₂Rh(CO)Cl and (Ph₃P)₃RhCl in the various clathrates was determined. It was found that significant leaching of the catalyst into the bulk aromatic solvent occurred, ranging from 13 to 94%. A related liquid clathrate, [Li·12-crown-4][InCl₄]·(C₆H₅CH₃)₂, had <1% of the dissolved catalyst leached.     

Reactions of RSe− (R = Me,Ph) Groups in [RSeFe(CO)4I and [RSeCr(CO)5−]

The anionic [MeSeFe(CO)₄] and [MeSeCr(CO)₅] complexes were synthesized by reaction of [PPN][HFe(CO)₄] and [PPN][HCr(CO)₅] with MeSeSeMe respectively via nucleophilic cleavage of the Se-Se bond. The ease of cleavage of the Se-Se bond follows the nucleophilic strength of metal-hydride complexes. Methylation of [RSeCr(CO)₅^?] by the soft alkylating agent MeI resulted in the formation of neutral (MeSeMe)Cr(CO)₅ in THF at 0°C. In contrast, the [ICr(CO)₅^?] was isolated at ambient temperature. Reaction of [MeSeFe(CO)₄^?] or [MeSeCr(CO)₅^?] with HBF₄ yielded (CO)₃Fc(μ-SeMe)₂Fe(CO)₃ dimer and anionic [(CO )₅Cr (μ-SeMe)Cr(CO)₅^?] respectively, and no neutral (HSeMe)Fe(CO)₄ and (HSeMe)Cr(CO)₅ were detected spectrally (IR) even at low temperature. Reaction of NOBF₄ or [Ph₃C][BF₄] and [MeSeCr(CO)₅^?] resulted in the neutral monodentate (MeSeSeMe)Cr(CO)₅ complex. Addition of 1 equiv CpFe(CO)₂I to 2 equiv [MeSeCr(CO)₅^?] gave CpFe(CO)₂(SeMe) and the anionic [(CO)₅Cr(μ-SeMe)Cr(CO)₅^?] in THF at ambient temperature.     

Synthesis amd characterization of [Et4,N]2[Mo(CO)4(SR)2] (R = Ph,Bz): New,potentially chelating bis-thiolate species

The new complexes [Et₄N]₂ [Mo(CO)₄(SR)₂] (R = Ph, Bz) have been prepared by reaction of [Et₄N] [SR] with (norbornadiene)Mo(CO)₄ at low temperature. The IR spectra and electrochemical behavior of these two species are different, perhaps implicating different conformational isomers with respect to the thiolate ligands. These complexes may prove to be valuable reagents for the synthesis of new heterometallic compounds, by virtue of their cis-monodentate thiolate ligands.