Dppf Ligand Research Articles

Novel Copper(I) Complexes Containing 1,1‘-Bis(diphenylphosphino)ferrocene (dppf) as a Chelate and Bridging Ligand: Synthesis of Tetrabridged Dicopper(I) Complexes [Cu2(μ-η1-C⋮R)2(μ-dppf)2] and X-ray Crystal Structure of [Cu2(μ-η1-C⋮CC6H4CH3-4)2(μ-dppf)2

Binuclear copper(I) complexes [Cu(κ2-P,P-dppf)(CH3CN)2][BF4] (1), [Cu(κ2-P,P-dppf)(bipy)][BF4] (2) containing the chelating dppf ligand (dppf = 1,1‘-bis(diphenylphosphino)ferrocene) have been prepared by substitution reactions of the acetonitrile ligands from the complexes [Cu(CH3CN)4][BF4] and (1) with dppf and bipy, respectively. Similarly, the treatment of the complex [Cu2(μ-dppm)2(CH3CN)2][BF4]2 with dppf in CH2Cl2 at room temperature gives the tetranuclear complex [Cu2(μ-dppm)2(κ2-P,P-dppf)2][BF4]2 (3). The analogous bridging chloride tetranuclear complex [Cu2(μ-Cl)2(κ2-P,P-dppf)2] (4) has been also prepared by the addition of dppf to a solution in THF containing an equimolar mixture of CuCl and tetramethylethylenediamine. Complex 4 has been used as a precursor for μ-η1-alkynyl bridging dicopper(I) complexes containing the framework [Cu2(μ-dppf)2]. Complexes [Cu2(μ-η1-C⋮CR)2(μ-dppf)2] (R = C6H4CH3-4 (5), C6H5 (6), CH2OCH3 (7), CH2CH2CH3 (8), (η5-C5H4)Fe(η5-C5H5) (9)) are obtained by the treatment of ...

Ferrocenyl phosphine mobility, positional isomerism and NMR fluxionality in triangular palladium sulfide aggregates. Crystal and molecular structures of [Pd3Cl2(η2-dppf )(μ-dppf )(μ3-S)2] and [Pd3Cl(η2-dppf )2(PPh3)(μ3-S)2]X [X = Cl or NO3, dppf = Fe(η5-C5H4PPh2)2

Three {Pd3S2} aggregates, [Pd3Cl2(η2-dppf)(µ-dppf)(µ3-S)2] and [Pd3Cl(η2-dppf)2(PPh3)(µ3-S)2]X [X = Cl or NO3, dppf = 1,1′-bis(diphenylphosphino)ferrocene] have been synthesized from metal addition to a {Pd2S2} molecular core in [Pd2(dppf)2(µ-S)2]. X-Ray single-crystal crystallographic analysis revealed a common sulfide-bicapped triangle with insignificant Pd· · ·Pd interactions. The former is neutral with a bridging and a chelating dppf ligand as well as two terminal chlorides. The dynamic behaviour has been studied by variable temperature 31P and 2-D COSY NMR. A phosphine–chloride interchange and phosphine–phosphine exchanges enable the two dppf ligands to migrate around the Pd3 plane. The solid-state structure corresponds to the static structure in solution at 198 K. The mixed phosphine complex 5a (X = Cl) is ionic with two Pd–dppf chelating rings and a {Pd(PPh3)Cl} moiety. With a PPh3 group taking up one site, it is stereochemically rigid. The other two complexes were studied by electrospray mass spectrometry (ESMS) in solution. The {Pd3S2} core in the mixed phosphine (X = NO3) is relatively stable to fragmentation under ESMS conditions.

Chelating versus bridging behaviour and NMR fluxionality of dppf in the nido clusters [M3Se2(CO)7(dppf )] [M = Fe or Ru, dppf = Fe(η5-C5H4PPh2)2]. Crystal structure of the chelated ruthenium derivative †

The reactions of [M3(CO)12] (M = Fe or Ru) with the diphosphine diselenide dppfSe2 [dppfSe2 = Fe(η5-C5H4P(Ph2)Se)2], in the presence of Me3NO afforded the disubstituted square pyramidal selenido clusters [Fe3Se2(CO)7(µ-dppf)] 1 and [Ru3Se2(CO)7(dppf)] 2. In the previously reported structure of 1 the dppf ligand bridges the two non-bonded iron atoms, whereas in 2 the same ligand chelates to one ruthenium atom of the basal plane of the square pyramidal cluster. Compound 2 represents the first reported example of chelating dppf to a carbonyl cluster. Both compounds exhibit fluxional behaviour in solution, consisting in the rocking motion of the bidentate bridging ligand below the square basal plane of the iron clusters in 1 and in the exchange of the axial and equatorial positions between the two chelating P atoms in 2. The dynamic behaviour of both compounds was studied by variable temperature 1-D and 2-D COSY and EXSY 1H NMR. The solid state structures correspond to the static structures in solution below 258 K for 1 and 213 K for 2. The cluster [Ru3Se2(CO)7(µ-dppe)] 3 [dppe = (CH2PPh2)2] has also been synthesized from dppeSe2, and its structure determined for comparison.

Synthesis, redox chemistry, and X-ray structure of the mixed-metal cluster Fe2(CO)6(μ3-S)2Ni(dppf)

The reaction between the dianion [Fe2(CO)6(μ2-S)2]2− and NiCl2(dppf) occurs readily at room temperature to give the mixed-metal cluster Fe2(CO)6(μ3-S)2Ni(dppf) in moderate yield. Fe2(CO)6(μ3-S)2Ni(dppf) was isolated by preparative chromatography and its solid-state structure established by X-ray diffraction analysis. Fe2(CO)6(μ3-S)2Ni(dppf) crystallizes in the monoclinic space group C2/c, a = 20.320(6), b = 13.114(2), c = 15.622(2) A, β = 110.25(2)°, V = 3905.4(11) A3, Z = 4, and d calc = 1.630 g/cm.3 The X-ray structure of Fe2(CO)6(μ3-S)2Ni(dppf) exhibits an Fe2S2Ni arachno polyhedral core, with the pendant dppf ligand attached to an essentially square planar Ni center. The redox chemistry of Fe2(CO)6(μ3-S)2Ni(dppf) was investigated by cyclic voltammetry which showed a reversible, one-electron oxidation localized on the Fe2S2 core along with an irreversible, one-electron reduction that is antibonding with respect to the Fe—Fe and Fe—S bonds. The electrochemical assignments were confirmed by carrying out extended Huckel MO calculations on the model cluster Fe2(CO)6(μ3-S)2Ni(H4-dppf).

Novel behaviour and reactivity in 1,1′-bis(diphenylphosphino)ferrocene and 1,1′-bis(diphenylphosphino)cobaltocene cluster derivatives

The clusters [Ru 6C(CO) 16{Fe(C 5H 4P(Ph) 2) 2}] 2 and [Ru 6C(CO) 15{ μ-Fe(C 5H 4P(Ph) 2) 2}] 3 have been synthesised from the reaction of the parent cluster [Ru 6C(CO) 17] 1 with 1,1′-bis(diphenylphosphino)ferrocene (dppf) in THF. The related compound [Ru 5C(CO) 13{ μ-Fe(C 5H 4P(Ph) 2) 2}] 4 is produced from 2 and 3 in more forcing conditions. Both clusters 3 and 4 have been structurally characterised by single crystal X-ray analysis. In 3 the dppf ligand is coordinated in the vicinal form and the cluster core is a highly distorted octahedron. In 4 the vicinal mode is retained but the dppf ligand is coordinated to adjacent basal atoms of a square-base pyramid. The 31P-NMR spectra of 3 and 4 in CD 2Cl 2 at various temperatures show a high degree of stereochemically non-rigid behaviour. Magnetic susceptibility measurements across a range of temperatures indicate that 3 is paramagnetic at all temperatures. An electrochemical study of 1, 3, 4 and the related [Ru 6C(CO) 15{ μ-dppm}] 5 has demonstrated a significant degree of communication between the redox-active sites in 3 and 4. The cluster [Ru 5C(CO) 13{ μ-Co(C 5H 4P(Ph) 2) 2}] 7 has also been synthesised from the direct reaction of the parent cluster [Ru 5C(CO) 15] 6 with 1,1′-bis(diphenylphosphino)cobaltocene (dppc). Synthesis of the dppc analogue of 3 was attempted but was thwarted by unfavourable redox chemistry. EPR spectra have been obtained for both dppc and 7. The oxidation product of 7 has also been produced ( 7 +) and displays a high degree of stereochemically non-rigid behaviour in a fashion similar to 3 and 4. The magnetic suceptibility of 7 has also been measured, showing an extraordinarily large magnetic moment at ambient temperature.

Controlled Acidolysis of Hexacarbonyltris(μ-alkoxo)dirhenium(I) Anions: Facile Synthesis of Hexacarbonylbis(μ-alkoxo)- [μ-1,1‘-bis(diphenylphosphino)ferrocene]dirhenium(I) Complexes and Nonacarbonyltris(μ-methoxo)(μ3-methoxo)trirhenium(I)

The complexes [Re2(μ-OR)2(μ-dppf)(CO)6] (R = H, 1; Me, 2; Et, 3; Ph, 4) were synthesized by the controlled acidolysis of the anions [Re2(μ-OR)3(CO)6]- (R = H, Me, Et) and [Re2(μ-OH)(μ-OPh)2(CO)6]- (5), respectively, in the presence of dppf (1,1‘-bis(diphenylphosphino)ferrocene). The dppf ligands in complexes 1−4 undergo a twisting motion in solution at room temperature, which, in the case of 3, is correlated with the restricted rotation of the ethyl groups about the O−CH2 bonds. Complex 3 is an interesting example of an organometallic complex in which the two exchanging positions of the methylene protons of an ethyl group are nonequivalent, while the exchanging positions of the methyl group are equivalent. Controlled acidolysis of [Re2(μ-OMe)3(CO)6]- under 1 atm of CO pressure affords the complex [Re3(μ-OMe)3(μ3-OMe)(CO)9]- (6), which consists of a Re3 triangle held together by one face-capping and three bridging methoxo groups, with no Re−Re bonds. The crystal structures of 1, 3, 5, and 6 were determined...

Preparation, characterization and electrochemical studies of 1,1′-bis(diphenylphosphino) ferrocene (dppf) derivatives. Crystal structure of [dppfCo(NO) 2][SbF 6

The neutral dppfFe(NO) 2 ( 1), the novel cationic [dppfCo(NO) 2][SbF 6] ( 2), as well as the dppfFe(CO) 3 ( 3) dppf = 1,1′-bis-(diphenylphosphino)ferrocene) complexes were prepared and characterized. The interaction between the two metallic centers through the dppf ligand was studied in the solid state by 57Fe Mössbauer spectroscopy and in solution by cyclic voltammetry. The Mössbauer parameters are compared with those of other dppfML n , complexes. Electrochemical studies performed on these complexes show the great influence of the ML n moiety on the redox processes of the dppf iron center. The crystal structure of complex 2 was determined (C 34H 28CoF 6FeN 2O 2P 2Sb). The compound crystallizes in the triclinic, space group P 1, a = 10.441(2), b = 10.755(2), c = 17.320(5) A ̊ , α = 104.10(2), β = 0.504(10), γ = 111.504(10)°, U = 1744.7(7) A ̊ 3, Z = 2, R = 0.0765, wR2 = 0.1878 . In this complex, the cobalt atom is coordinated to two nitrosyl ligands and to phosphorus atoms of the dppf ligand, providing a distorted tetrahedral geometry.

A novel octa-substituted iridium carbonyl derivative containing the dehydrogenated dppf ligand (dppf=Fe(C 5H 4PPh 2) 2): synthesis and crystal structure of [H 4Ir 4(CO) 4{Fe(C 5H 3PPh 2)(C 5H 4P(Ph)C 6H 4)} 2

The octa-substituted iridium carbonyl derivative [H 4Ir 4(CO) 4{Fe(C 5H 3PPh 2)(C 5H 4P(Ph)C 6H 4)} 2] prepared from [Ir 4(CO) 12] and dppf consists of a tetrahedral Ir 4 unit and two tetradentate dehydrogenated dppf ligands formed upon ortho-metallation of a cyclopentadienyl and a phenyl ring with each iridium atom coordinated by a carbonyl group, a phosphorus and an ortho-carbon of the dehydrogenated cyclopentadienyl or phenyl group.

Synthesis and redox chemistry of 1,1′-bis(diphenylphosphino)ferrocene derivatives of R 2C 2Co 2(CO) 6 (R  MeO 2C, CF 3)

Fe(C 5H 4PPh 2) 2 (dppf) undergoes facile thermal substitution reactions with R 2C 2Co 2(CO) 6 (R  MeO 2C, CF 3) to yield a variety of products. When R  MeO 2C, initial coordination gives μ 2-(MeO 2C 2) 2C 2Co 2(CO) 5( η 1-dppf); its crystal and molecular structure, monoclinic, P2 1/c, a = 8.954(3), b = 20.211(2) c = 23.836(5) A ̊ , β = 100.55(2)°, Z = 4, R1 = 0.0345 for 5764 reflections 1 > 2 σ(1), confirms the monodentate coordination mode for dppf. At low dppf/alkyne-complex ratios, oligomeric products with dppf ligands linking up to five (μ 2-MeO 2C) 2C 2Co 2 modules have been characterised but, as the proportion of the phosphine ligand increases. unstable products, which include a η 1- μ- η 1 dppf configuration, are obtained as well. In contrast, for R  CF 3, only [(CF 3) 2C 2]Co 2(CO) 4( η 2-dppf) is found in significant yield. A molecule with two different reduction centres, [ μ 2-(MeO 2C) 2C 2Co 2(CO) 5]( μ-dppf)[Co 3( μ 3-CPh)(CO) 8], was also characterised. Electrochemistry of the dppf complexes was characterised by fast ligand dissociation upon reduction of the (μ-alkyne)Co 2 redox centre and oxidation of coordinated dppf. There was no evidence for communication between redox centres.

Variable-temperature nuclear magnetic resonance spectroscopic studies of the dynamic behaviour of the mixed-metal cluster compounds [MM′Ru4H2(µ-dppf)(CO)12][M = M′= Cu, Ag or Au; M = Cu, M′= Au; dppf = Fe(η5-C5H4PPh2)2] and the crystal structures of [MM′Ru4H2(µ-dppf)(CO)12](M = Cu or Au, M′= Au)

The free energies of activation (ΔG‡) for the fluxional processes in the clusters [M2Ru4H2(µ-dppf)(CO)12][M = Cu 1, Ag 2 or Au 3; dppf = 1,1′-bis(diphenylphosphino)ferrocene] have been determined by band-shape analysis of variable-temperature 1H or 31P-{1H} NMR spectra. In solution, the dppf ligand attached to the coinage metals in each of 1–3 undergoes dynamic behaviour involving inversion at the phosphorus atoms, together with twisting of the cyclopentadienyl rings, and values of 47.0 ± 0.2, 51.5 ± 0.1 and 48.8 ± 0.2 kJ mol–1 were obtained for ΔG‡ of this fluxional process in 1–3, respectively. The metal cores of these three clusters are also stereochemically non-rigid in solution and values of ΔG‡ of 47.7 ± 0.2 and 39.9 ± 0.4 kJ mol–1 have been calculated for a coinage-metal site-exchange process in 1 and 2, respectively. The new trimetallic cluster [AuCuRu4(µ3-H)2(µ-dppf)(CO)12]4, which is closely related to the bimetallic clusters 1–3, has been synthesized in ca. 40% yield by treating [Cu2Ru4(µ3-H)2(µ-dppf)(CO)12] with the complex [AuCl(SC4H8)]. Variable-temperature 1H NMR studies on 4 demonstrate that the dppf fluxion still occurs in solution (ΔG‡ 49.2 ± 0.2 kJ mol–1), but the metal skeleton of the cluster is stereochemically rigid, which is in marked contrast to those of the bimetallic analogues 1–3. The structures of [MM′Ru4H2(µ-dppf)(CO)12](M = Cu or Au, M′= Au) have been established by single-crystal X-ray diffraction studies. The metal framework of 4 consists of a tetrahedron of ruthenium atoms with one face capped by the copper atom and one CuRu2 face of the CuRu3 tetrahedron so formed is capped by the gold atom to give an overall capped trigonal-bipyramidal metal-core geometry [Cu–Au 2.641(1), Cu–Ru 2.755(1)–2.909(2), Au–Ru 2.780(1) and 2.815(1), Ru–Ru 2.783(1)–2.998(1)Å]. The other two CuRu2 faces are capped by triply bridging hydrido ligands, the dppf ligand bridges the two coinage metals and each ruthenium atom is bonded to three terminal CO groups. The skeletal geometry of 3 is reasonably similar to that of 4, with a second gold atom replacing the copper atom. However, one of the Au–Ru distances [3.558(2)Å] is too long for any significant bonding interaction between the two metal atoms, so the metal framework of 3 is somewhat distorted towards a capped square-pyramid [Au–Au 2.901(1), Au–Ru 2.771(1)–2.846(1), Ru–Ru 2.775(2)–3.016(1)Å]. As observed for 4, the bidentate diphosphine ligand bridges the two Group 11 metals in 3 and each ruthenium atom is bonded to three terminal CO groups, but one of the hydrido ligands bridges a Ru–Ru vector rather than capping an AuRu2 face.

Coupling H2 to Electron Transfer with a 17-Electron Heterobimetallic Hydride: A “Redox Switch” Model for the H2-Activating Center of Hydrogenase

A meta-stable heterobimetallic mixed-valence ion, [Fe(II),Ru(III)], is formed by the one-electron oxidation of Cp*(dppf)RuH {1, dppf = 1,1‘-bis(diphenylphosphino)ferrocene, Cp* = pentamethylcyclopentadienide}. A remarkable stability toward one-electron oxidation is revealed by the cyclic voltammetry of 1 which contains two reversible oxidations at +0.073 and +0.541 V and a quasireversible oxidation at +0.975 V (vs NHE) assigned to Ru(III/II), Ru(IV/III), and Fe(III/II), respectively. The isolable Ru(III) metal hydride, [Cp*(dppf)RuH]PF6 (1+), is characterized by a NIR absorption at 912 nm (ε = 486 M-1 cm-1) assigned to an intervalence transfer band and a series of atom transfer reactions yielding the even electron derivatives [Cp*(dppf)RuXH]PF6 (X = H, Cl, Br, I). A crystallographically determined Fe−Ru distance of 4.383(1) Å in 1 is consonant with the classification of 1+ as a weakly coupled, Type II mixed-valence ion (Hab = 627 cm-1, α2 = 3.3 × 10-3). This is the first reported example of a mixed-valence bimetallic complex containing the widely used dppf ligand. The ability of 1 to serve as a heterobimetallic catalyst for the reduction of methyl viologen with H2 makes it a unique functional model of [NiFe] hydrogenase enzymes.

Aurophilicity at Sulfur Centers. Synthesis and Reactivity of the Complex [S(Au2dppf)]; Formation of Polynuclear Sulfur-Centered Complexes. Crystal Structures of [S(Au2dppf)]·2CHCl3, [(μ-Au2dppf){S(Au2dppf)}2](OTf)2· 8CHCl3, and [S(AuPPh2Me)2(Au2dppf)](ClO4)2·3CH2Cl2

Treatment of [Au2Cl2(μ-dppf)] (dppf = 1,1‘-bis(diphenylphosphino)ferrocene) with Li2S (molar ratio 1:1) in ethanol gives a yellow solid [S(Au2dppf)] (1). The sulfur atom in complex 1 can coordinate several neutral or cationic gold(I) fragments giving the trinuclear neutral [S{Au(C6F5)}(Au2dppf)] (2) or cationic derivatives [S(AuL)(Au2dppf)]ClO4 [L = CH2PPh3 (3), PPh3 (4), PPh2Me (5)]. A pentanuclear complex [Au{S(Au2dppf)2}]ClO4 (6) is obtained by reaction of 2 equiv of complex 1 with 1 equiv of [Au(tht)2]ClO4, in which the central gold atom is bonded to two sulfur atoms. Treatment of compound 1 with [Au2(OTf)2(μ-dppf)] (OTf = trifluoromethylsulfonate) in a molar ratio 2:1 affords the hexanuclear complex [(μ-Au2dppf){S(Au2dppf)}2](OTf)2 (7), in which two SAu3 units are joined through the dppf ligand. The reaction of 1 with 2 equiv of [Au(OClO3)PR3] leads to the quadruply bridging derivatives [S(AuPR3)2(Au2dppf)](ClO4)2 [PR3 = PPh3 (8), PPh2Me (9)]. Crystal structure determinations were performed for complexes 1, 7, and 9. [S(Au2dppf)] (1) crystallizes in the monoclinic space group P2/n, with a = 12.571(4) Å, b = 10.579(4) Å, c = 15.212(4) Å, β = 107.84(3)°, Z = 2, T = −130 °C. [(μ-Au2dppf){S(Au2dppf)}2](OTf)2 (7) is triclinic, P1̄, with a = 15.177(3), b = 18.408(4), c = 27.894(8) Å, α = 88.83(2), β = 84.46(2), γ = 67.78(2), Z = 2, T = −100 °C. [S(AuPPh2Me)2(Au2dppf)](ClO4)2 (9) is triclinic, P1̄, with a = 13.727(2) Å, b = 15.952(3) Å, c = 17.763(2) Å, α = 71.738(12)°, β = 73.264(14)°, γ = 75.96(2)°, Z = 2, T = −100 °C. All three complexes display short gold(I)−gold(I) interactions.

The heteronuclear cluster chemistry of the group IB metals—18. Synthesis, structural characterization and dynamic behaviour of the bimetallic hexanuclear group IB metal cluster compounds [M 2Ru 4H 2(μ-dppf)(CO) 12] [M = Cu, Ag or Au; dppf = Fe(η 5-C 5H 5PPh 2) 2]. X-ray crystal structure of [Cu 2Ru 4(μ 3-H) 2(μ-dppf)(CO) 12

Treatment of a dichloromethane solution of the salt [N(PPh 3] 2] 2[Ru 4(μ-H) 2(CO) 12] with two equivalents of the complex [M(NCMe) 4]PF 6 (M = Cu or Ag) at −30°C, followed by the addition of one equivalent of 1,1′-bis(diphenylphosphino)ferrocene (dppf) affords the mixed-metal clusters [M 2Ru 49μ-H) 2(μ-dppf)(CO) 12] [M = Cu ( 1) or Ag ( 2)] in ca 45–60% yield. The analogous gold-containing species [Au 12Ru 4H 2(μ-dppf)(CO) 12] ( 3) was obtained in ca 70% yield by treating an acetone solution of [N(PPh 3) 2] 2[Ru 4(μ-H) 2(CO) 12] with a dichloromethane solution of the complex [Au 2(μ-dppf)Cl 2], in the presence of T1PF 6. The novel cluster compounds 1–3 have been characterized by IR and NMR spectroscopy and the structure of 1 has been determined by a single-crystal X-ray diffraction study. The metal core structure of 1 consists of a tetrahedron of ruthenium atoms capped by a copper atom, with one of the CuRu 2 faces of the CuRu 3 tetrahedron so formed further capped by a second copper atom to give a capped trigonal bipyramidal skeletal geometry. The other two CuRu 2 faces of the CuRu 3 tetrahedron are each capped by a triply bridging hydrido ligand, the bidentate diphosphine ligand bridges the two coinage metals and each ruthenium atom is bonded to three terminal CO groups. The spectroscopic data of the silver- and gold-containing species 2 and 3 are closely similar to those of 1, which suggests that 2 and 3 adopt similar metal core structures to that established for 1. However, the possibility that the capped trigonal bipyramidal metal framework of 3 is distorted by the dppf ligand towards a capped square-based pyramidal skeletal geometry cannot be excluded with the evidence available. Variable-temperature 1H and 31P{ 1H} NMR studies show that, at ambient temperatures in solution, the metal frameworks of all of the clusters undergo dynamic behaviour involving coinage metal site exchange, even though the two Group IB metals are linked together by the bidentate diphosphine ligand dppf. Free energies of activation ( ΔG ‡ ) at the coalescence temperature of 47±1, 40±1 and ca 33 kJ mol −1 have been calculated for the skeletal rearrangements from the coalescence temperatures observed in the variable-temperature 31P{ 1H} NMR spectra of clusters 1, 2 and 3, respectively. These values of ΔG ‡ are compared with those of structurally related analogous clusters. In addition, the dppf ligand attached to the coinage metals in each of 1–3 is also stereochemically non-rigid in solution at room temperature and it undergoes a process involving inversion of configuration at the phosphorus atoms, together with twisting of the cyclopentadienyl rings. The skeletal rearrangement process and the fluxional behaviour of the dppf ligand are definitely independent for clusters 2 and 3.

X-ray diffraction structure of the 1,1′-bis(diphenylphosphino)ferrocene (dppf)-bridged complex [(dppf)AgCl]2: An unexpected product from the reaction betweencis-(bpy)2RuCl2 and dppf in the presence of AgBF4

The reaction betweencis-Ru(bpy)2Cl2 (where bpy=bipyridine) and the diphosphine ligand 1,1′-bis(diphenylphosphino)ferrocene (dppf) in the presence of AgBF4 has led to the isolation of the title compound [Ag(dppf)Cl]2. [Ag(dppf)Cl]2 has been structurally characterized by X-ray diffraction analysis, which confirms the bridging mode adopted by the ancillary dppf ligand and the centrosymmetric nature of this molecule. Dimeric [Ag(dppf)Cl]2 crystallizes in the triclinic space group\(P\bar 1\),a=11.426(1) A,b=11.509(1) A,c=12.786(1) A, α=68.96(2)°, β=70.66(2)°, γ=71.24(2)°,V=1441(1) A3,Z=1,dcalc=1.608 g·cm−3;R=0.0445,Rw=0.0566 for 4486 observed reflections withl>3σ(l)

1,1′-Bis(diphenylphosphino)ferrocene complexes of gold(I). Polymeric [AuCl(μ-dppf)] n and dimeric [Au 2(dppf-P,P′) 2(μ-dppf)](NO 3) 2

Addition of molar equivalent of [Au 2Cl 2(μ-dppf)] to [Fe(C 5H 4PPh 2) 2] (dppf) gives an intermediate complex [AuCl(dppf)] x ( 1) which readily polymerises in solution to give [AuCl(dppf)] n . nCH 2Cl 2( 2). X-ray diffraction analysis of 2 revealed a repeating unit of [AuCl(dppf)] propagating one-dimensionally along the c axis to give a zigzag chain. Complex 1 metathesises with AgNO 3 to give [Au(NO 3)(dppf)] x which reacts with HCO 2Na to give [Au 2(dppf- P, P′) 2(μ-dppf)](NO 3) 2.2H 2O ( 3) as one of the products. The X-ray structure of 3 shows a centrosymmetric dimeric framework with two Au(dppf) chelates bridged by a dppf ligand. Both 2 and 3 show negligible inter- or intramolecular Au ⋯ Au interactions.

Solution Characterization, Conformation Analysis, and Dynamics of the Ligand 1,1'-Bis(diphenylphosphino)ferrocene (dppf) in Re2(.mu.-OMe)2(.mu.-dppf)(CO)6

The dynamic process involving the diphenyls (O, O') in 1,1'-bis(diphenylphosphino)ferrocene (dppf) in [Re 2 (μ-OMe) 2 (μ-dppf)(CO) 6 ] at 228 K is characterized by conformational analysis. At this temperature, the fluxionality of the dppf ligand ceases whereas the dynamics of the phenyl rings about the P-C ipso(O,O') (the «ipso» in the phenyl rings) was rapid on the NMR time scale down to -85 o C. The fluxional barrier (ΔG * exp =46.4±1.0 kJ/mol) for the interconversion of the R and the S forms was determined by variable-temperature 1 H NMR spectroscopic studies

Structure of an iridium complex of 1,1'-bisdiphenylphosphinoferrocene

The structure of [1,1'-bis(diphenylphosphino)ferrocene](η 4 -1,5-cyclooctadiene)iridium(I) hexafluorophosphate, [Ir(C 8 H 12 ){(C 5 H 4 -PPh 2 ) 2 Fe}][PF 6 ], shows approximately square-planar geometry at iridium. The cyclopentadienyl rings of the dppf ligand are close to parallel and staggered

Heteropolymetallic complexes of 1,1?-bis (diphenylphosphino)ferrocene, dppf. VIII. X-ray crystal structure of copper(I) dimer [(?-dppf)(Cu(dppf))2](ClO4)2 1

The dimeric Cu(I) complex [(μ-dppf)(Cu(dppf))2](ClO4)2, where dppf is Fe((n5-C5H4)P-(C6H5)2)2, has been characterized by single-crystal X-ray crystallography. The complex crystallizes in the triclinic space groupP1 (no. 2) with unit cell parametersa=21.852(5),b=18.063(5),c=14.867(5)A, α=114.32(3), β=109.87(3), γ=82.84(3)°. The structure was refined toR=5.40% based on 5562 observed reflections. Two crystallographically independent, structurally equivalent, units were observed in the structure. The structure consists of the centrosymmetric dimeric [(μ-dppf) (Cu(dppf))2]2+ cations and ClO4/− anions. The copper atoms are three-coordinate being trigonally bonded to one chelating and one bridging ligand. The P-Cu-P bond angles for the chelating dppf ligand are 111.1(2)° and 111.3(2)°, while the P-Cu-P angles linking different dppf molecules range from 123.9(2) to 124.2(2)°. Cu-P bond distances fall within normal ranges lying between 2.265(5) and 2.285(4)A, with the values for the chelating dppf being slightly larger than those observed for the bridging ligand. The cyclopentadienyl rings are exactly staggered and parallel, and the P atoms 180° opposed in the bridging dppf, while the rings maintain an approximately staggered configuration and are inclined by 1.6° to each other with the P atoms being 39.5° apart in the chelating ligand. A steric control of the stereochemistry of the monomer fragment of the dimer complex is suggested.

1,1′-Bis(diphenylphosphino)ferrocene ligand substitution in the benzylidyne-capped cluster PhCCo 3(CO) 9. Synthesis, X-ray structure, and redox reactivity of PhCCo 3(CO) 7(dppf)

The reaction between 1,1′-bis(diphenylphosphino)ferrocene (dppf) and the tricobalt cluster PhCCo 3(CO) 9 ( 1) yields the disubstituted cluster PhCCo 3(CO) 7(dppf) ( 2). The dppf ligand in 2 bridges adjacent cobalt centers via axial coordination. Ligand substitution leading to 2 may be achieved by thermolysis, oxidative decarbonylation using trimethylamine oxide, and by electrontransfer chain (ETC) catalysis using sodium benzophenone ketyl. The isolated yield of 2 ranged from 50 to 70% in all cases. Solution characterization of 2 by FT-IR and 31P NMR spectroscopy is presented along with the single-crystal X-ray diffraction results. The dppf-bridged cluster PhCCo 3(CO) 7(dppf)·(toluene) crystallized in the monoclinic space group P2 1/ c with a = 13.560(3), b = 17.339(3), c = 21.482(3) Å, β = 106.81(1)°, V = 4835(1) Å 3 and Z = 4. Block-cascade least-squares refinement yielded R = 0.0630 for 5055 ( I > 3σ( I)) reflections. The redox reactivity of 2 was examined by cyclic voltammetry, which revealed the presence of two irreversible oxidations that are attributed to the oxidation of the dppf ligand and the cluster core along with the observation of an irreversible reduction that exhibits cyclic voltammetric curve crossing. All of the redox processes are discussed with respect to existing tricobalt cluster redox chemistry.