Synthesis and characterization of rhodium complexes with phosphine-stabilized germylenes

The reaction of phosphine-stabilized germylenes (1a,b) with dimer complex [Rh(2)(μ-Cl)(2)(COD)(2)] leads to the corresponding phosphine-germylene-Rh(I) complexes (2a,b). Interestingly, the stability of these complexes depends strongly on the nature of the substituent of the germylene fragment. Indeed, the complex (2a) with the chloro-germylene ligand isomerizes into a metallacycle rhodium complex (3a) via germylene insertion into the Rh-Cl bond, while the complex with the phenyl-substituted germylene (2b) was isolated and represents the first stable Rh(I)-germylene complex with a Rh-Cl bond.     

Synthesis and characterization of rhenium(VII) oxide complexes of phenothiazines

Summary Five complexes of rhenium(VII) oxide with N-alkylphenothiazines have been synthesized and characterized on the basis of elemental analyses, molar conductances, and u.v.-vis., i.r. and n.m.r. spectral data. The molecular formulas of the new ionic complexes are: [ReO₃(PTZ)₂(H₂O)][ReO₄], PTZ = chlorpromazine, promethazine or ethopropazine; [ReO₃(TF)(H₂O)][ReO₄], TF = trifluoperazine; and [ReO₃(TR)₃][ReO₄(H₂O)₂]·H₂O, TR = thioridazine. Tentative structures have been proposed.     

Synthesis, characterization and reactivity of tribenzylphosphine rhodium and iridium complexes

New rhodium and iridium complexes, with the formula [MCl(PBz₃)(cod)] [M = Rh (1), Ir (2)] and [M(PBz₃)₂(cod)]PF₆ [M = Rh (3), Ir (4)] (cod = 1,5-cyclooctadiene), stabilized by the tribenzylphosphine ligand (PBz₃) were synthesized and characterized by elemental analysis and spectroscopic methods. The molecular structures of 1 and 2 were determined by single-crystal X-ray diffraction. The addition of pyridine to a methanol solution of 1or 2, followed by metathetical reaction with NH₄PF₆, gave the corresponding derivatives [M(py)(PBz₃)(cod)]PF₆ [M = Rh (5), Ir (6)]. At room temperature in CHCl₃ solution, 4 converted spontaneously to the ortho-metallated complex [IrH(PBz₃)(cod){η²-P,C-(C₆H₄CH₂)PBz₂}]PF₆ (7) as a mixture of cis/trans isomers via intramolecular C-H activation of a benzylic phenyl ring. The reaction of 3 or 4 with hydrogen in coordinating solvents gave the dihydrido bis(solvento) derivative [M(H)₂(S)₂(PBz₃)₂]PF₆ (M = Rh, Ir; S = acetone, acetonitrile, THF), that transformed into the corresponding dicarbonyls [M(H)₂(CO)₂(PBz₃)₂]PF₆ by treatment with CO. Analogous cis-dihydrido complexes [M(H)₂(THF)₂(py)(PBz₃)₂]PF₆ (M = Rh, Ir) were observed by reaction of the py derivatives 5 and 6 with H₂.     

Diorganotin complexes of carboxylates: synthesis and characterization

Diorganotin complexes of monoisopropyl and monomethyl nadiate, succinate, and phthalate were synthesized and characterized by elemental analysis, FT-IR, ¹H NMR, ¹³C NMR, and ¹¹⁹Sn NMR spectroscopic techniques. The spectroscopic investigation demonstrated that carboxylate is bidentate in the diorganotin complexes. On the basis of ¹ J(¹¹⁹Sn–¹³C) and ² J(¹¹⁹Sn–¹H) values, C–Sn–C bond angles were also calculated. The newly synthesized complexes were also screened for their antibacterial activities against Gram-positive and Gram-negative pathogenic strains of bacteria.     

N-fused pentaphyrins and their rhodium complexes: oxidation-induced rhodium rearrangement

meso-Aryl-substituted pentaphyrins were isolated in the modified Rothemund-Lindsey porphyrin synthesis as a 22-pi-electron N-fused pentaphyrin ([22]NFP5) and a 24-pi-electron N-fused pentaphyrin ([24]NFP5), which were reversibly interconvertible by means of two-electron reduction with NaBH4 or two-electron oxidation with dichlorodicyanobenzoquinone (DDQ). Judging from 1H NMR data, [22]NFP5 is aromatic and possesses a diatropic ring current, while [24]NFP5 exhibits partial anti-aromatic character. Metalation of [22]NFP5 1 with a rhodium(I) salt led to isolation of rhodium complexes 9 and 10, whose structures were unambiguously characterized by X-ray diffraction analyses and were assigned as conjugated 24-pi and 22-pi electronic systems, respectively. In the rhodium(I) metalation of 1, the complex 9 was a major product at 20 degrees C, but the complex 10 became preferential at 55 degrees C. Upon treatment with DDQ, compound 9 was converted to 10 with an unprecedented rearrangement of the rhodium atom.     

Polynuclear germanylmercury complexes of lanthanides

Conclusions The transmetallation of [(C₆F₅)₃Ge]₂Hg with metallic praseodymium, neodymium, and holmium yielded complexes [(C₆F₅)₃Ge]₇Hg₂Ln·3DME (DME is dimethoxyethane), for which the ionic structure {[(C₆F₅)₃Ge]₇Hg₂}^3–Ln³⁺·3DME was proposed on the basis of electrical conductivity and chemical properties.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2589–2594, November, 1981.The authors thank O. N. Babkina at the Institute of Chemical Physics of the Academy of Sciences of the USSR for electrical conductivity measurements.     

Polynuclear isocyanide complexes of rhenium

The arylation of carbonylgold chloride with diarylzinc compounds yields either triarylgoldzinc or diarylgoldzinc chlorides, depending on the reactant ratio and the nature of the aryl group. The same reactions with diphenylcadmium and diphenylmercury yield exclusively diphenylgoldcadmium chloride and diphenylgoldmercury chloride, respectively. The reactions of the products with N,N,N′,N′-tetramethylethylenediamine and triphenylphosphine were studied.Phenylgold has been obtained as a very unstable solid from diphenylgoldzinc chloride and diphenylgoldmercury chloride.     

Solvent-free synthesis of bisferrocenylimines and their rhodium(I) complexes

The solvent-free reaction of ferrocenecarboxaldehyde and diaminoalkanes under solvent-free conditions gave bisferrocenylimines (L) in excellent yields. Cationic rhodium(I) complexes with the formulation [Rh(COD)(L)]ClO₄ were prepared by the reaction of [Rh(COD)Cl]₂ with the bisferrocenylimines in the presence of silver perchlorate. The compounds were characterised by NMR, IR, MS and elemental analysis. The X-ray crystal structures of two rhodium(I) complexes are also reported.     

The synthesis of new chiral rhodium complexes and their crystal structures

Two novel chiral rhodium complexes were successfully synthesized from the reaction of chiral bidentate nitrogen ligands with RhCl₃·3H₂O in ethanol under reflux. Their unusual crystal structures were unambiguously obtained by X‐ray analysis. Copyright © 2001 John Wiley & Sons, Ltd.     

Synthesis and characterization of half-sandwich N-heterocyclic carbene complexes of cobalt and rhodium

A series of novel half-sandwich M(I) and M(III) complexes (M = Co, Rh) bearing the N-heterocyclic carbene ligand 1,3-dimesitylimidazol-2-ylidene (IMes) have been prepared and characterized. Thus, (eta5-C(5)R(5))M(IMes)(C(2)H(4))(M = Co, Rh; R = H, Me) were obtained from the corresponding bis(ethene) complexes (eta5-C(5)R(5))M(C(2)H(4))(2), except for CpRh(IMes)(C(2)H(4)) which was prepared via the novel 16-electron Rh(I) compound Rh(IMes)(C(2)H(4))(2)Cl. The carbonyl compounds (eta5-C(5)R(5))Co(IMes)(CO)(R = H, Me) were synthesized by thermal CO substitution of (eta5-C(5)R(5))Co(CO)(2). A diamagnetic, apparently 16-electron Co(III) compound [CpCo(IMes)I](+)[I(3)(-)] was obtained from CpCo(IMes)(CO) and I(2). Finally, Co(III) and Rh(III) complexes CpCo(IMes)Me(2) and Cp*Rh(IMes)Me(2) were prepared by methylation of [CpCo(IMes)I](+)[I(3)(-)], and ligand exchange at Cp*Rh(Me(2)SO)Me(2), respectively. The molecular structures of CpCo(IMes)(CO), CpRh(IMes)(C(2)H(4)), Cp*Rh(IMes)(C(2)H(4)), and Cp*Rh(IMes)Me(2) were determined by single crystal X-ray diffraction. Steric and electronic factors imposed by the strongly donating and sterically demanding IMes ligand are discussed on the basis of X-ray crystallographic, NMR, and IR spectroscopic analyses. Very poor correlations are found between values for (1)J(Rh-C(carbene)) and dRh-C(carbene) data for Rh(i) N,N-heterocyclic carbene complexes including literature data and this work.     

Sigma-borane complexes of iridium: synthesis and structural characterization

Reaction of NaBH4 with (tBuPOCOP)IrHCl affords the previously reported complex (tBuPOCOP)IrH2(BH3) (1) (tBuPOCOP = kappa(3)-C6H3-1,3-[OP(tBu)2]2). The structure of 1 determined from neutron diffraction data contains a B-H sigma-bond to iridium with an elongated B-H bond distance of 1.45(5) A. Compound 1 crystallizes in the space group P1 (Z = 2) with a = 8.262 (5) A, b = 12.264 (5) A, c = 13.394 (4) A, and V = 1256.2 (1) A(3) (30 K). Complex 1 can also be prepared by reaction of BH3 x THF with (tBuPOCOP)IrH2. Reaction of (tBuPOCOP)IrH2 with pinacol borane gave initially complex 2, which is assigned a structure analogous to that of 1 based on spectroscopic measurements. Complex 2 evolves H2 at room temperature leading to the borane complex 3, which is formed cleanly when 2 is subjected to dynamic vacuum. The structure of 3 has been determined by X-ray diffraction and consists of the (tBuPOCOP)Ir core with a sigma-bound pinacol borane ligand in an approximately square planar complex. Compound 3 crystallizes in the space group C2/c (Z = 4) with a = 41.2238 (2) A, b = 11.1233 (2) A, c = 14.6122 (3) A, and V = 6700.21 (19) A(3) (130 K). Reaction of (tBuPOCOP)IrH2 with 9-borobicyclononane (9-BBN) affords complex 4. Complex 4 displays (1)H NMR resonances analogous to 1 and exists in equilibrium with (tBuPOCOP)IrH2 in THF solutions.     

Polynuclear carbonyltrialkylphosphine complexes of zerovalent palladium

The synthesis of three new polynuclear carbonyltrialkylphosphine complexes of Pd⁰ is described. The formulae Pd₁₂(CO)₁₅ (PEt₃)7, Pd₁₂ (CO)₁₂ (PBu₃)₇ and Pd₁₂(CO)₁₇ (PBu3)₅ are proposed for the new complexes.     

Synthesis and electronic characterization of bipyridine dithiolate rhodium(III) complexes

Five new mixed diimine 1,1'-dithiolate or dithiocarbamate ligand complexes of the form [Rh(bpy)2(SS)][PF6]n, where bpy = 2,2'-bipyridine and SS = various substituted dialkyldithiocarbamates or 1,1'-dithiolates, were synthesized from cis-[Rh(bpy)2(OTf)2][OTf]. The triflate ligands are easily displaced by other ligands and allow these syntheses to proceed in high yields (80-90% overall) under relatively mild reaction conditions and to give high purity products. Electrochemistry shows irreversible two-electron reduction of Rh(III) to Rh(I) and a concomitant loss of one bipyridine ligand; this is followed by reversible one-electron reduction of the remaining 2,2'-bipyridine ligand. The electronic characterizations of these complexes are consistent with significant delocalization of the sulfur electron density onto the empty metal d orbitals. The 1,1'-dithiolate ligands induce larger red shifts in the absorption and emission spectra than the dithiocarbamates as the 1,1'-dithiolates have a more extensive conjugation system.     

New efficient method for the synthesis of haloadamantanes involving rhodium complexes

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2897–2898, December, 1991.     

Carbene complexes of rhodium and iridium from tripodal N-heterocyclic carbene ligands: synthesis and catalytic properties

Two tripodal trisimidazolium ligand precursors have been tested in the synthesis of new N-heterocyclic carbene rhodium and iridium complexes. [Tris(3-methylbenzimidazolium-1-yl)]methane sulfate gave products with coordination of the decomposed precursor. [1,1,1-Tris(3-butylimidazolium-1-yl)methyl]ethane trichloride (TIMEH(3)(Bu)) coordinated to the metal in a chelate and bridged-chelate form, depending on the reaction conditions. The crystal structures of two of the products are described. The compounds resulting from the coordination with TIME(Bu) were tested in the catalytic hydrosilylation of terminal alkynes.     

Polynuclear metal complexes incorporating hydrido-phosphido ligands

Addition of phosphines to the coordinatively unsaturated species (Cp)₂M₂(CO)₄ (M = Mo, W) and H₂Os₃(CO)₁₀ yield a series of products incorporating terminal phosphine along with bridging and capping phosphido ligands formed via insertion into PH bonds. The complexes were characterised by ¹H and ³¹P NMR spectroscopy and mass spectrometry.     

Cationic methyl complexes of rhodium(III): synthesis, structure, and some reactions

Cationic methyl complex of rhodium(III), trans-[Rh(Acac)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] (1) is prepared by interaction of trans-[Rh(Acac)(PPh₃)₂(CH₃)I] with AgBPh₄ in acetonitrile. Cationic methyl complexes of rhodium(III), cis-[Rh(Acac)(PPh₃)₂ (CH₃)(CH₃CN)][BPh₄] (2) and cis-[Rh(BA)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] (3) (Acac, BA are acetylacetonate and benzoylacetonate, respectively), are obtained by CH₃I oxidative addition to rhodium(I) complexes [Rh(Acac)(PPh₃)₂] and [Rh(BA)(PPh₃)₂] in acetonitrile in the presence of NaBPh₄. Complexes 2 and 3 react readily with NH₃ at room temperature to form cis-[Rh(Acac)(PPh₃)₂(CH₃)(NH₃)][BPh₄] (4) and cis-[Rh(BA)(PPh₃)₂(CH₃)(NH₃)][BPh₄] (5), respectively. Complexes 1-5 were characterized by elemental analysis, ¹H and ³¹P{¹H} NMR spectra. Complexes 1, 2, 3 and 4 were characterized by X-ray diffraction analysis. Complexes 2 and 3 in solutions (CH₂Cl₂, CHCl₃) are presented as mixtures of cis-(PPh₃)₂ isomers involved into a fluxional process. Complex 2 on heating in acetonitrile is converted into trans-isomer 1. In parallel with that isomerization, reductive elimination of methyl group with formation of [CH₃PPh₃][BPh₄] takes place. Replacement of CH₃CN in complexes 1 and 2 by anion I⁻ yields in both cases the neutral complex trans-[Rh(Acac)(PPh₃)₂(CH₃)I]. Strong trans influence of CH₃ ligand manifests itself in the elongation (in solid) and labilization (in solution) of rhodium-acetonitrile nitrogen bond.     

Dicarbollide complexes of rhodium and ruthenium

The 7,8-B₉C₂H₁₁^2- ion reacts with (Ph₃P)₂Rh(CO)Cl to form (B₉C₂H₁₁)-Rh(Cl)(Ph₃P)₂. This rhodacarborane reacts with NaBPh₄ to produce (B₉C₂H₁₁-Rh(Ph₃P)(Ph₄B). The new metallocarboranes [(B₉C₂H₁₁)Rh(Ph₃P)(C₆H₆)]₂ and (B₉C₂H₁₁)Rh(H)(Ph₃P) were obtained from the reaction of B₉C₂H₁₁^2- and (Ph₃P)₃RhCl. The ruthenacarboranes (B₉C₂H₁₁)Ru(CO)(Ph₃P)₂ and (B₉C₂H₁₁-Ru(CO)₃ · 0.5C₆H₆ were prepared from (Ph₃P)Ru(CO)₂Cl₂ and [Ru(CO)₃Cl₂]₂ respectively.