Trifluoroacetylacetonate rhodium(III) methyl complexes, cis-[Rh(TFA)(PPh3)2(CH3)(L)][BPh4] and cis-[Rh(TFA)(PPh3)2(CH3)(I)] (L = CH3CN, NH3, pyridine), in comparison with their acetylacetonate analogs

The oxidative addition of CH₃I to planar rhodium(I) complex [Rh(TFA)(PPh₃)₂] in acetonitrile (TFA is trifluoroacetylacetonate) leads to the formation of cationic, cis-[Rh(TFA)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] (1), or neutral, cis-[Rh(TFA)(PPh₃)₂(CH₃)(I)] (4), rhodium(III) methyl complexes depending on the reaction conditions. 1 reacts readily with NH₃ and pyridine to form cationic complexes, cis-[Rh(TFA)(PPh₃)₂(CH₃)(NH₃)][BPh₄] (2) and cis-[Rh(TFA)(PPh₃)₂(CH₃)(Py)][BPh₄] (3), respectively. Acetylacetonate methyl complex of rhodium(III), cis-[Rh(Acac)(PPh₃)₂(CH₃)(I)] (5), was obtained by the action of NaI on cis-[Rh(Acac)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] in acetone at −15 °C. Complexes 1-5 were characterized by elemental analysis, ³¹P{¹H}, ¹H and ¹⁹F NMR. For complexes 2, 3, 4 conductivity data in acetone solutions are reported. The crystal structures of 2 and 3 were determined. NMR parameters of 1-5 and related complexes are discussed from the viewpoint of their isomerism.     

Koordinativ ungesättigte Dieisenkomplexe: Synthese und Kristallstrukturen von [Fe2(CO)4(μ‐H)(μ‐PtBu2)(μ‐Ph2PCH2PPh2)] und [Fe2(CO)4(μ‐CH2)(μ‐H)(μ‐PtBu2)(μ‐Ph2PCH2PPh2)]

Coordinatively Unsaturated Diiron Complexes: Synthesis and Crystal Structures of [Fe₂(CO)₄(μ‐H)(μ‐P^tBu₂)(μ‐Ph₂PCH₂PPh₂)] and [Fe₂(CO)₄(μ‐CH₂)(μ‐H)(μ‐P^tBu₂)(μ‐Ph₂PCH₂PPh₂)] [Fe₂(μ‐CO)(CO)₆(μ‐H)(μ‐P^tBu₂)] ( 1 ) reacts spontaneously with dppm (dppm = Ph₂PCH₂PPh₂) to give [Fe₂(μ‐CO)(CO)₄(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] ( 2 c ). By thermolysis or photolysis, 2 c loses very easily one carbonyl ligand and yields the corresponding electronically and coordinatively unsaturated complex [Fe₂(CO)₄(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] ( 3 ). 3 exhibits a Fe–Fe double bond which could be confirmed by the addition of methylene to the corresponding dimetallacyclopropane [Fe₂(CO)₄(μ‐CH₂)(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] ( 4 ). The reaction of 1 with dppe (Ph₂PC₂H₄PPh₂) affords [Fe₂(μ‐CO)(CO)₄(μ‐H)(μ‐P^tBu₂)(μ‐dppe)] ( 5 ). In contrast to the thermolysis of 2 c , yielding 3 , the heating of 5 in toluene leads rapidly to complete decomposition. The reaction of 1 with PPh₃ yields [Fe₂(CO)₆(H)(μ‐P^tBu₂)(PPh₃)] ( 6 a ), while with ^tBu₂PH the compound [Fe₂(μ‐CO)(CO)₅(μ‐H)(μ‐P^tBu₂)(^tBu₂PH)] ( 6 b ) is formed. The thermolysis of 6 b affords [Fe₂(CO)₅(μ‐P^tBu₂)₂] and the degradation products [Fe(CO)₃(^tBu₂PH)₂] and [Fe(CO)₄(^tBu₂PH)]. The molecular structures of 3 , 4 and 6 b were determined by X‐ray crystal structure analyses.     

Oxidative addition of methyl iodide to [Rh(PhCOCHCOPh)(CO)(P(OCH2)3CCH3)]: an experimental and computational study

The reaction rate of the oxidative addition and CO insertion steps of methyl iodide with [Rh(PhCOCHCOPh)(CO)(P(OCH₂)₃CCH₃)] are presented. Large negative experimental values for the activation entropy and results from a density functional theory computational chemistry study indicated trans addition of the CH3I to [Rh(PhCOCHCOPh)(CO)(P(OCH₂)₃CCH₃)]. A study of the molecular orbitals gives insight into the flow of electrons during the oxidative addition reaction. CO insertion leads to a square pyramidal [Rh(PhCOCHCOPh)(P(OCH₂)₃CCH₃)(COCH₃)(I)] acyl product with the COCH3 moiety in the apical position. The strong electron donation of the P(OCH₂)₃CCH₃ ligand accelerates the oxidation addition step of methyl iodide to [Rh(PhCOCHCOPh)(CO)(P(OCH₂)₃CCH₃)] by ca. 265 times faster (at 35°C) than that of the Monsanto catalyst, but inhibits the CO insertion step.     

[Fe2(μsb‐CO)(CO)3(NO)(μ‐PtBu2)(μ‐Ph2PCH2PPh2)]: Synthese,Kristallstruktur und Koordinationsisomerie

[Fe₂(μ_sb‐CO)(CO)₃(NO)(μ‐P^tBu₂)(μ‐Ph₂PCH₂PPh₂)]: Synthesis, X‐ray Crystal Structure and Isomerization Na[Fe₂(μ‐CO)(CO)₆(μ‐P^tBu₂)] ( 1 ) reacts with [NO][BF₄] at —60 °C in THF to the nitrosyl complex [Fe₂(CO)₆(NO)(μ‐P^tBu₂)] ( 2 ). The subsequent reaction of 2 with phosphanes (L) under mild conditions affords the complexes [Fe₂(CO)₅(NO)L(μ‐P^tBu₂)], L = PPh₃, ( 3a ); η‐dppm (dppm = Ph₂PCH₂PPh₂), ( 3b ). In this case the phosphane substitutes one carbonyl ligand at the iron tetracarbonyl fragment in 2 , which was confirmed by the X‐ray crystal structure analysis of 3a . In solution 3b loses one CO ligand very easily to give dppm as bridging ligand on the Fe‐Fe bond. The thus formed compound [Fe₂(CO)₄(NO)(μ‐P^tBu₂)(μ‐dppm)] ( 4 ) occurs in solution in different solvents and over a wide temperature range as a mixture of the two isomers [Fe₂(μ_sb‐CO)(CO)₃(NO)(μ‐P^tBu₂)(μ‐dppm)] ( 4a ) and [Fe₂(CO)₄(μ‐NO)(μ‐P^tBu₂)(μ‐dppm)] ( 4b ). 4a was unambiguously characterized by single‐crystal X‐ray structure analysis while 4b was confirmed both by NMR investigations in solution as well as by means of DFT calculations. Furthermore, the spontaneous reaction of [Fe₂(CO)₄(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] ( 5 ) with NO at —60 °C in toluene yields a complicated mixture of products containing [Fe₂(μ‐CO)(CO)₄(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] ( 6 ) as main product beside the isomers 4a and 4b occuring in very low yields.     

Iodomethane oxidative addition and CO migratory insertion in monocarbonylphosphine complexes of the type [Rh((C6H5)COCHCO((CH2)nCH3))(CO)(PPh3)]: Steric and electronic effects

The chemical kinetics, studied by UV/Vis, IR and NMR, of the oxidative addition of iodomethane to [Rh((C₆H₅)COCHCOR)(CO)(PPh₃)], with R = (CH₂)_nCH₃, n = 1-3, consists of three consecutive reaction steps that involves isomers of two distinctly different classes of Rh^III-alkyl and two distinctly different classes of Rh^III-acyl species. Kinetic studies on the first oxidative addition step of [Rh((C₆H₅)COCHCOR)(CO)(PPh₃)] + CH₃I to form [Rh((C₆H₅)COCHCOR)(CH₃)(CO)(PPh₃)(I)] revealed a second order oxidative addition rate constant approximately 500-600 times faster than that observed for the Monsanto catalyst [Rh(CO)₂I₂]⁻. The reaction rate of the first oxidative addition step in chloroform was not influenced by the increasing alkyl chain length of the R group on the β-diketonato ligand: k₁ = 0.0333 ([Rh((C₆H₅)COCHCO(CH₂CH₃))(CO)(PPh₃)]), 0.0437 ([Rh((C₆H₅)COCHCO(CH₂CH₂CH₃))(CO)(PPh₃)]) and 0.0354 dm³ mol⁻¹ s⁻¹ ([Rh((C₆H₅)COCHCO(CH₂CH₂CH₂CH₃))(CO)(PPh₃)]). The pK_a^′ and keto-enol equilibrium constant, K_c, of the β-diketones (C₆H₅)COCH₂COR, along with apparent group electronegativities, χ_R of the R group of the β-diketones (C₆H₅)COCH₂COR, give a measurement of the electron donating character of the coordinating β-diketonato ligand: (R, pK_a^′, K_c, χ_R) = (CH₃, 8.70, 12.1, 2.34), (CH₂CH₃, 9.33, 8.2, 2.31), (CH₂CH₂CH₃, 9.23, 11.5, 2.41) and (CH₂CH₂CH₂CH₃, 9.33, 11.6, 2.22).     

Carbonyl cationic rhodium(I) and iridium(I) complexes with sulphur donor and triphenylphosphine ligands

Summary The reaction of previously reported Rh^I and Ir^I cationic complexes towards carbon monoxide and triphenylphosphine has been studied. Carbonyl rhodium(I) mixed complexes of the formulae [Rh(CO)L₂(PPh₃)]ClO₄, (L=tetrahydrothiophene(tht), trimethylene sulfide(tms), SMe₂, or SEt₂), [(CO)(PPh₃)Rh{-(L-L)}₂Rh(PPh₃)(CO)](ClO₄)₂ (L-L= 2,2,7,7-tetramethyl-3,6-dithiaoctane (tmdto), (MeS)₂(CH₂)₃ (dth), or 1,4-dithiacyclohexane (dt), [Rh(CO)L(PPh₃)₂]ClO₄ (L= tht, tms, SMe₂, or SEt₂), and carbonyl iridium(I) complexes of the formulae [Ir(CO)₂(COD)(PPh₃)]ClO₄, [Ir(CO)(COD)(PPh₃)₂]ClO₄, [(CO)(COD)(PPh₃) Ir{-(L-L)} Ir(PPh₃)(COD)(CO)](ClO₄)₂ (L-L = tmdto or dt), [(CO)₂ (PPh₃)Ir(-tmdto)Ir(PPh₃)(CO)₂](ClO₄)₂, [(CO)₂(PPh₃) Ir(-dt)₂Ir(PPh₃)(CO)₂](ClO₄)₂, were prepared by different synthetic methods.     

Complexes dinucleaires pontes des metaux d8: VII. Reactions d'addition oxydante d'halogenures d'alkyle et d'acycle aux complexes μ-halogenes du rhodium(i) [RhX(CO)(PR3)]2. Structure cristalline de [RhCl(CO)(PMe2Ph)(Me)(Br)]2

The halogen bridged binuclear complexes of rhodium(I) [RhCl(CO)(PR₃)]₂ undergo oxidative addition with methyl halides to yield the complexes [RhCl(CO)(PR₃)(Me)(X)]₂ (X = Cl, Br). The crystal and molecular structures of [RhCl(CO)(PMe₂Ph)(Me)(Br)]₂ have been determined from a single crystal by use of X-ray crystallographic methods. The space group is Pca2₁ or Pacm with a 19.501(5), b 10.381(4), c 13.641(5) e? Z = 4. Parameters of 30 nonhydrogen atoms in the space group Pca2₁ were refined by the full-matrix least squares technique to a conventional R factor of 0.073. In a binuclear unit, each rhodium atom is in an octahedral environment being bonded to a carbonyl group, a methyl group and a tertiary phosphine ligand and three halogen atoms for which, due to a disorder phenomenon, the diffusion factors have been determined as the average between those of chlorine and bromine atoms. In solution the cis-migration of the methyl groups occurs, leading to the acetyl complexes. In the case of CH₃I, it is shown that an equilibrium is present in solution: [RhCl(CO)(PR₃(Me)(I)]₂ ? [RhCl(COMe)(PR₃)(I)(solvant)]₂] Carbonylation reactions shift this equilibrium to give the complexes [RhCl(CO)(COMe)(PR₃(I)]₂. Such complexes are readily prepared by direct oxidative addition of acyl halides to the compounds [RhCl(CO)(PR₃)]₂.     

Koordinativ ungesättigte Dirutheniumkomplexe: Synthese und Kristallstrukturen von [Ru2(CO)n(μ‐H)(μ‐PtBu2)(μ‐Ph2PCH2PPh2)] (n = 4; 5) und [Ru2(CO)4(μ‐CH2)(μ‐H)(μ‐PtBu2)(μ‐Ph2PCH2PPh2)]

Coordinatively Unsaturated Diruthenium Complexes: Synthesis and X‐ray Crystal Structures of [Ru₂(CO)_n(μ‐H)(μ‐P^tBu₂)(μ‐Ph₂PCH₂PPh₂)] (n = 4; 5) and [Ru₂(CO)₄(μ‐CH₂)(μ‐H)(μ‐P^tBu₂)(μ‐Ph₂PCH₂PPh₂)] The reaction of [Ru₂(μ‐CO)(CO)₅(μ‐H)(μ‐P^tBu₂)(^tBu₂PH)] ( 2 ) with dppm yields the dinuclear species [Ru₂(μ‐CO)(CO)₄(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] ( 3 ) (dppm = Ph₂PCH₂PPh₂). Under thermal or photolytic conditions 3 loses very easily one carbonyl ligand and affords the corresponding electronically and coordinatively unsaturated complex [Ru₂(CO)₄(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] ( 4 ). 4 is also obtainable by an one‐pot synthesis from [Ru₃(CO)₁₂], an excess of ^tBu₂PH and stoichiometric amounts of dppm via the formation of [Ru₂(CO)₄(μ‐H)(μ‐P^tBu₂)(^tBu₂PH)₂] ( 1 ). 4 exhibits a Ru–Ru double bond which could be confirmed by addition of methylene to the dimetallacyclopropane [Ru₂(CO)₄(μ‐CH₂)(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] ( 5 ). The molecular structures of 3 , 4 and 5 were determined by X‐ray crystal structure analyses.     

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.     

Reactivity of cationic methyl rhodium(III) complexes cis-[Rh(β-diket)(PPh3)2(CH3)(CH3CN)][BPh4] toward ligands of different character: pyridine, carbon monoxide, and triphenylphosphine

Cationic methyl complex of rhodium(III), cis-[Rh(Acac)(PPh₃)₂(CH₃)(Py)][BPh₄] (1) as a single isomer with Py in the trans to PPh₃ position, is formed upon the reaction of cis-[Rh(Acac)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] with pyridine in methylene chloride solution.Complex 1 was characterized by elemental analysis and by ³¹P{¹H} and ¹H NMR spectra.Cationic pentacoordinate acetyl complexes, trans-[Rh(Acac)(PPh₃)₂(COCH₃)][BPh₄] (2) and trans-[Rh(BA)(PPh₃)₂(COCH₃)][BPh₄] (3), are prepared by action of carbon monoxide on cis-[Rh(Acac)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] and cis-[Rh(BA)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄], respectively, in methylene chloride solutions.Complexes 2 and 3 were characterized by elemental analysis and by IR, ³¹P{¹H}, ¹³C{¹H} and ¹H NMR. According to NMR data, 2 and 3 in solution are non-fluxional trigonal bipyramids with β-diketonate and acetyl ligands in the equatorial plane and axial phosphines.In solutions, 2 and 3 gradually isomerize into octahedral methyl carbonyl complexes trans-[Rh(Acac)(PPh₃)₂(CO)(CH₃)][BPh₄] (4) and trans-[Rh(BA)(PPh₃)₂(CO)(CH₃)][BPh₄] (5), respectively.Complexes 4 and 5 were characterized by IR, ³¹P{¹H}, ¹³C{¹H} and ¹H NMR, without isolation.Upon the action of PPh₃ on cis-[Rh(Acac)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] and cis-[Rh(BA)(PPh₃)₂(CH₃)(CH₃CN)] [BPh₄], reductive elimination of the methyl ligand as a phosphonium salt, [CH₃PPh₃][BPh₄], occurs to give square planar rhodium(I) complexes [Rh(Acac)(PPh₃)₂] and[Rh(BA)(PPh₃)₂], respectively. The reaction products were identified in the reaction mixtures by ³¹P{¹H} and ¹H NMR.     

[RhCl(CO)(PPh3)]2. A precursor for the synthesis of cationic rhodium complexes with nitrogen donor ligands

Summary The use of [RhCl(CO)(PPh₃)]₂ as a precursor for the synthesis of complexes of the types [Rh(CO)L₂(PPh₃)]A (A = [ClO₄]^– or [BPh₄]^–; L = pyridine type ligand) and [Rh(CO)(L-L)(PPh₃)]A (A = [ClO₄]^– or [BPh₄]^–; L-L = bidentate nitrogen donor) and the preparation of several complexes of the types [Rh(CO)L(PPh₃){P(p-RC₆H₄)₃}]BPh₄ and [Rh(CO)(phen)(PPh₃){P(p-RC₆H₄)₃}]A (A = [ClO₄]^– or [BPh₄]^–; R = H or Me) is described.Author to whom all correspondence should be directed.     

Three-Coordinate Rhodium Complexes in Low Oxidation States

The isolation of simultaneously low-coordinate and low-valent compounds is a timeless challenge for preparative chemists. This work showcases the preparation and full characterization of tri-coordinate rhodium(-I) and rhodium(0) complexes as well as a rare rhodium(I) complex. Reduction of [{Rh(μ-Cl)(IPr)(dvtms)}₂] ( 1 , IPr=1,3-bis(2,6-diisopropylphenyl)imidazolyl-2-ylidene; dvtms=divinyltetramethyldisiloxane) with KC₈ gave the trigonal complexes K[Rh(IPr)(dvtms)] and [Rh(IPr)(dvtms)], whereas the cation [Rh(IPr)(dvtms)]⁺ results from their oxidation or by abstraction of chloride from 1 with silver salts. The paramagnetic Rh⁰ complex is a unique fully metal-centered radical with the unpaired electron in the d_z2 orbital. The Rh(-I) complex reacts with PPh₃ with replacement of the NHC ligand, and behaves as a nucleophile, which upon reaction with [AuCl(PPh₃)] generates the trigonal pyramidal complex [(IPr)(dvtms)Rh-Au(PPh₃)] with a metal–metal bond between two d¹⁰ metal centers.     

Synthesis,formation constants and reactions of cationic rhodium(I) complexes of nitriles

Reactions of Rh(ClO₄)(CO)(PPh₃)₂ with nitriles produce new cationic rhodium(I) complexes, [RhL(CO)(PPh₃)₂]ClO₄ [L = CH₃CN (1), CH₃CH₂CH₂CN (2) or C₆H₅CN (3)], whose spectral data suggest that the nitriles are coordinated through the nitrogen atom. Formation constants for the reaction Rh(ClO₄)(CO)(PPh₃)₂ + L ⇋ [RhL(CO)(PPh₃)₂]ClO₄, have been measured to be 1.01 × 10⁵ M⁻¹ (CH₃CN), 1.07 × 10⁵ M⁻¹ (CH₃CH₂CH₂CN) and 2.59 × 10⁴ M⁻¹ (C₆H₅CN) at 25°C in monochlorobenzene. The differences in the formation constants for the different nitriles seem to be predominantly due to differences in ΔH (not to differences in ΔS). The nitriles in 1–3 are readily replaced with nitrogen base ligands (unsaturated nitriles and pyridine) and PPh₃.     

Rhodium(I) complexes with bis(pyrazolyl)methane ligands. Crystal structure of [Rh(COD)(CH2(Pz)2)]ClO4·12 C2H4Cl2

The synthesis and properties of neutral and cationic complexes of general formulae [{RhCl(diolefin)}₂(CH₂(pz)₂)], [Rh(CO)₂ (CH₂(pz)₂)][RhCl₂(CO)₂], (Rh(diolefin)(CH₂(pz)₂)]ClO₂, [{Rh(diolefin)(PPh₃)}₂(CH₂(pz)₂)](ClO₄)₂, [Rh(CO)₂(CH₂(pz)₂)]ClO₄ and [Rh(CO)(CH₂(pz)₂)(PPh₃)]ClO₄ are described. The NMR spectra of [Rh(COD)(CH₂(pz)₂)]ClO₄ complexes are discussed. X-ray structural analysis of [Rh(COD)(CH₂(Pz)₂)]ClO₄ · $\text{1}\text{2}$C₂H₄Cl₂ is presented; the final R factor is 0.061 for 2436 observed data, recorded with Cu-K_α, not corrected for absorption and with the sample inside a capillary. The Rh atom presents a distorted square planar coordination in a mononuclear arrangement. The COD ring has a twisted boat conformation, and the two halves of the CH₂(Pz)₂ moiety, which are quite similar to one another, form an angle of 47.2(4)°.     

Clusterkomplexe [M2Rh(μ‐PCy2)(μ‐CO)2(CO)8] mit triangularem Metallgerüst RhM2 (M = Mn,Re; M2 = MnRe): Synthese,Struktur, Ringöffnungen und Katalysatoreigenschaften für die Isomerisierung und Hydroformylierung von 1‐Hexen

Cluster Complexes [M₂Rh(μ‐PCy₂)(μ‐CO)₂(CO)₈] with Triangular Core of RhM₂ (M = Re, Mn; M₂ = MnRe): Synthesis, Structure, Ring Opening Reaction, and Properties as Catalysts for Hydroformylation and Isomerisation of 1‐Hexene The salts PPh₄[M₂(μ‐H)(μ‐PCy₂)(CO)₈] and Rh(COD)[ClO₄] were in equimolar amounts reacted at –40 to –15 °C in the presence of CO_(g) in CH₂Cl₂/methanol solution under release of PPh₄[ClO₄] to intermediates. Such species formed in a selective reaction the unifold unsaturated 46 valence electrons title compounds [M₂Rh(μ‐PCy₂)(μ‐CO)₂(CO)₈] (M = Re 1 , Mn 2 ; M₂ = MnRe 3 ) in yields of > 90%; analogeous the derivatives with the PPh₂ bridge could the obtained (M = Re 4 , Mn 5 ). From these clusters the molecular structure of 2 was determined by a single crystal X‐ray analysis. The exchange of the labil CO ligand attached at the rhodium ring atom in 1 – 3 against selected tertiary and secondary phosphanes in solution gave the substitution products [M₂RhL(μ‐PCy₂)(μ‐CO)₂(CO)₇] (M = Re: L = PMe₃ 6 , P(n‐Bu)₃ 7 , P(n‐C₆H₄SO₃Na)₃ 8 , HPCy₂ 9 , HPPh₂ 10 , HPMen₂ 11 , M₂ = MnRe: L = HPCy₂ 12 ) nearly quantitative. Such dimanganese rhodium intermediates ligated with secondary phosphanes were converted in a subsequent reaction to the ring‐opened complexes [MnRh(μ‐PCy₂)(μ‐H)(CO)₅Mn(μ‐PR₂)(CO)₄] (M = Mn: R = Cy 13 , Ph 14 , Mn 15 ). The molecular structure of 13 , which showed in the time scale of the ³¹P NMR method a fluxional behaviour, was determined by X‐ray structure analysis. All products obtained were always characterized by means of υ(CO)Ir, ¹H and ³¹P NMR measurements. From the reactants of hydroformylation process, CO_(g) 1 – 2 in different solvents afforded at 20 °C under a reversible ring opening reaction the valence‐saturated complexes [MRh(μ‐PCy₂)(CO)₇M(CO)₅] (M = Re 16 , Mn 17 ), whereas the reaction of CO_(g) and the ring‐opened 13 to [MnRh(μ‐PCy₂)(μ‐H)(CO)₆Mn(μ‐PCy₂)(CO)₄] ( 18 ) was as well reversible. The molecular structures of 17 and 18 were determined by X‐ray analysis. The υ(CO)IR, ¹H and ³¹P NMR measurements in pressure‐resistant reaction vessels at 20 °C ascertained the heterolytic splitting of hydrogen in the reaction of 1 – 2 dissolved in CDCl₃ or THF‐d₈ under formation of product monoanions [M₂Rh(μ‐CO)(μ‐H)(μ‐PCy₂)(CO)₉]^– (M = Re, Mn), which also were formed by the reaction of NaBH₄ and 1 – 2 . Finally, the substrate 1‐hexene and 1 and 3 gave under the release of the labil CO ligand an η²‐coordination pattern of hexene, which was weekened going from the Re to the Mn neighbor atoms. After the results of the catalytic experiments with 1 and 2 as catalysts, such change in the bonding property revealed an advantageous formation of hydroformylation products for the dirhenium rhodium catalyst 1 and that of isomerisation products of hexene for the dimanganese rhodium catalyst 2 . Par example, 1 generated n‐heptanal/2‐methylhexanal in TOF values of 246 [h^–1] (n/iso = 3.4) and the c,t‐hexenes in that of 241 [h^–1]. Opposotite to this, 2 achieved such values of 55 [h^–1] (n/iso = 3.6) and 473 [h^–1]. A triphenylphosphane substitution product of 1 increased the activity of the hydroformylation reaction about 20%, accompanied by an only gradually improved selectivity. The hydrogenation products like alcohols and saturated hydrocarbons known from industrial hydroformylation processes were not observed. The metals manganese and rhenium bound at the rhodium reaction center showed a cooperative effect.     

Acyl and α-Ketoacyl Complexes of Pt(II) with Weak Donor Ligands

Treatment of trans-Pt(COCOPh)(Cl)(PPh₃)₂ (1a) with AgBF₄in THF led to the formation of a metastatic complex trans-[Pt(COCOPh)(THF)(PPh₃)₂](BF₄) (2) which readily underwent ligand substitution to give a cationic aqua complex trans-[Pt(COCOPh)(OH₂)(PPh₃)₂](BF₄) (5a). Complex 5a has been characterized spectroscopically and crystallographically. Analogous reaction of trans-Pt(COCOOMe)(Cl)(PPh₃)₂ (1b) with Ag(CF₃SO₃) in dried CH₂C1₂ was found first to yield a methoxyoxalyl triflato complextrans-Pt(COCOOMe)(OTf)(PPh₃)₂ (6). Attempts to crystallize the triflato product in CH₂-cl₂hexane under ambient conditions also afforded an aqua complex of the triflate salt f/wu-[Pt(COCOOMe)(OH₂)(PPhj)₂](CF₃SO₃) (5b). Complex 5a in a noncoordinating solvent such as CH₂C1₂ or CHCl₃ suffered spontaneous decarbonylation to form first cis-[Pt(COPh)(CO)(PPh₃)₂l(BF₄) (3a) then the thermodynamically stable isomer trans-[Pt(COPh)(CO)(PPh₃)₂](BF₄) (3b). Crystallization of complex 3b under ambient conditions resulted in an aqua benzoyl complex trans-[Pt(COPh)(OH₂)(PPh₃)₂](BF₄) (7). The replacement of the H_2O ligand in complex 7 by CO was done simply by bubbling CO into the solution of 7. The single crystal structures of 5b and 7 have been determined by X-ray diffraction. The distances of the Pt-O bonds in 5a, 5b, and 7 support that the aqua ligand is a weak donor in such cationic aquaorganoplatinum(lI) complexes, in agreement with their lability to the substitution reactions.     

The reactions of [Co(η-C5H5)(CO)(L)] (L = R3P or RNC) with carbon disuphide and organoisothiocyanates

The reactions of [Co(η-C₅H₅)(CO)(PR₃)] or [Co(η-C₅GH₅)(CO)₂]/R₃P mixtures (R = alkyl or aryl) with CS₂ in refluxing CS₂ or CS₂/toluene gives rise to [Co(η-C₅H₅)(PR₃)(CS)], [Co(η-C₅H₅)(PR₃)(CS₂)], [Co(η-C₅H₅)(PR₃)(CS₃)], and [Co₃(η-C₅H₅)₃ (CS)(S)] in reasonable yields. The corresponding reactions using PhNCS give [Co(η-C₅H₅)(PPh₃)(PhNCS)] and a polymeric species which appears to be [Co₄(η-C₅H₅)₄ (PhNCS)]. Similar products are obtained with [Co(η-C₅H₅)(CO)(CNR)] or [Co(η0C₅H₅)(CO)₂]/RNC mixtures.     

Chemistry of transition‐metal complexes containing functionalized phosphines: synthesis and structural analysis of rhodium(I) complexes containing allyl and cyanoalkylphosphines

A series of related acetylacetonate–carbonyl–rhodium compounds substituted by functionalized phosphines has been prepared in good to excellent yields by the reaction of [Rh(acac)(CO)₂] (acac is acetylacetonate) with the corresponding allyl‐, cyanomethyl‐ or cyanoethyl‐substituted phosphines. All compounds were fully characterized by ³¹P, ¹H, ¹³C NMR and IR spectroscopy. The X‐ray structures of (acetylacetonato‐κ²O,O′)(tert‐butylphosphanedicarbonitrile‐κP)carbonylrhodium(I), [Rh(C₅H₇O₂)(CO)(C₈H₁₃N₂)] or [Rh(acac)(CO)(^tBuP(CH₂CN)₂}] ( 2b ), (acetylacetonato‐κ²O,O′)carbonyl[3‐(diphenylphosphanyl)propanenitrile‐κP]rhodium(I), [Rh(C₅H₇O₂)(C₁₅H₁₄N)(CO)] or [Rh(acac)(CO){Ph₂P(CH₂CH₂CN)}] ( 2h ), and (acetylacetonato‐κ²O,O′)carbonyl[3‐(di‐tert‐butylphosphanyl)propanenitrile‐κP]rhodium(I), [Rh(C₅H₇O₂)(C₁₁H₂₂N)(CO)] or [Rh(acac)(CO){^tBu₂P(CH₂CH₂CN)}] ( 2i ), showed a square‐planar geometry around the Rh atom with a significant trans influence over the acetylacetonate moiety, evidenced by long Rh—O bond lengths as expected for poor π‐acceptor phosphines. The Rh—P distances displayed an inverse linear dependence with the coupling constants J_P‐Rh and the IR ν(C[triple‐bond]O) bands, which accounts for the Rh—P electronic bonding feature (poor π‐acceptors) of these complexes. A combined study from density functional theory (DFT) calculations and an evaluation of the intramolecular H…Rh contacts from X‐ray diffraction data allowed a comparison of the conformational preferences of these complexes in the solid state versus the isolated compounds in the gas phase. For 2b , 2h and 2i , an energy‐framework study evidenced that the crystal structures are mainly governed by dispersive energy. In fact, strong pairwise molecular dispersive interactions are responsible for the columnar arrangement observed in these complexes. A Hirshfeld surface analysis employing three‐dimensional molecular surface contours and two‐dimensional fingerprint plots indicated that the structures are stabilized by H…H, C…H, H…O, H…N and H…Rh intermolecular interactions.     

Synthese und Struktur chiraler Heterometallatetrahedrane des Typs [Re2(M1PPh3)(M2PPh3)(μ‐PCy2)(CO)7C≡CPh] (M1 = Ag,Au; M2 = Cu,Ag, Au)

Syntheses and Structure of Chiral Metallatetrahedron Complexes of the Type [Re₂(M¹PPh₃)(M²PPh₃)(μ‐PCy₂)(CO)₇C≡CPh] (M¹ = Ag, Au; M² = Cu, Ag, Au) From the reaction of Li[Re₂(μ‐H)(μ‐PCy₂)(CO)₇(C(Ph)O)] ( 1 ) with Ph₃AuC≡CPh both benzaldehyde and the trinuclear complex Li[Re₂(AuPPh₃)(μ‐PCy₂)(CO)₇C≡CPh] ( 2a ) were obtained in high yield. The complex anion was isolated as its PPh₄‐salt 2b . The latter reacts with coinage metal complexes PPh₃M²Cl [M² = Cu, Ag, Au] to give chiral heterometallatetrahedranes of the general formula [Re₂(AuPPh₃)(M²PPh₃)(μ‐PCy₂)(CO)₇C≡CPh] (M² = Cu 3a , Ag 3b , Au 3c ). The corresponding complex [Re₂(AgPPh₃)₂(μ‐PCy₂)(CO)₇C≡CPh] ( 3d ) is obtained from the reaction of [Re₂(AgPPh₃)₂(μ‐PCy₂)(CO)₇Cl] ( 4 ) with LiC≡CPh. 3d undergoes a metathesis reaction in the presence of PPh₃CuCl giving [Re₂(AgPPh₃)(CuPPh₃)(μ‐PCy₂)(CO)₇C≡CPh] ( 3e ) and PPh₃AgCl. Analogous metathesis reactions are observed when 3c is reacted with PPh₃AgCl or PPh₃CuCl giving 3a or 3b , respectively. The reaction of 1 with PPh₃AuCl gives benzaldehyde and Li[Re₂(AuPPh₃)(μ‐PCy₂)(CO)₇Cl] ( 5a ) which upon reaction with PhLi forms the trinuclear complex Li[Re₂(AuPPh₃)(μ‐PCy₂)(CO)₇Ph] ( 6a ). Again this complex was isolated as its PPh₄‐salt 6b . In contrast to 2b , 6b reacts with one equivalent of Ph₃PAuCl by transmetalation to give Ph₃PAuPh and PPh₄[Re₂(AuPPh₃)(μ‐PCy₂)(CO)₇Cl] ( 5b ). The X‐ray structures of the compounds 3a , 3b , 3e and 4 are reported.     

Synthesis of [TpRu(CO)(PPh3)]2(μ-CHCHCHCHC6H4CHCHCHCH) from Wittig reactions

Treatment of [Ru(CHCHCH₂PPh₃)X(CO)(PPh₃)₂]⁺ (X=Cl, Br) with KTp (Tp=hydridotris(pyrazolyl)borate) and NaBPh₄ produced [TpRu(CHCHCH₂PPh₃)(CO)(PPh₃)]BPh₄. Reaction of RuHCl(CO)(PPh₃)₃ with HCCCH(OEt)₂ produced Ru(CHCHCH(OEt)₂)Cl(CO)(PPh₃)₂, which reacted with KTp to give TpRu(CHCHCHO)(CO)(PPh₃). Treatment of [TpRu(CHCHCH₂PPh₃)(CO)(PPh₃)]BPh₄ with NaN(SiMe₃)₂ and benzaldehyde produced TpRu(CHCHCHCHPh)(CO)(PPh₃). The later complex was also produced when TpRu(CHCHCHO)(CO)(PPh₃) was treated with PhCH₂PPh₃Cl/NaN(SiMe₃)₂. The bimetallic complex [TpRu(CO)(PPh₃)]₂(μ-CHCHCHCHC₆H₄CHCHCHCH) was obtained from the reaction of [TpRu(CHCHCH₂PPh₃)(CO)(PPh₃)]BPh₄ with NaN(SiMe₃)₂ and terephthaldicarboxaldehyde.