Iridium Dimer Research Articles

Synthesis, NMR, and X-ray Molecular Structure of a Butadienesulfinate Iridium Dimer and Its Transformation into a Mononuclear Cp*IrCl[(1,2,5-η)-SO2CHCRCHCHR] Complex

A metathesis reaction of [Cp*IrCl 2 ] 2 with butadienesulfinate lithium (SO 2 CHCRCHCHR)-Li (R = H, 1Li; Me, 2Li) affords the dinuclear compounds [Cp*Ir(Cl) 2 {(5-η)-SO 2 CH=CRCH= CHR}(Li)(THF)] 2 (R = H, 3; Me, 4), respectively. The single-crystal X-ray analysis of 3 and 4 reveals the presence of metallacyclic, five- and eight-membered rings, which easily break to afford compounds Cp*IrCl[(1,2,5-η)-SO 2 CH=CRCH=CHR] [R = H, (5), Me (6)], upon displacement of THF and LiCl. The 1 H and 1 3 C NMR data are consistent with the single-crystal X-ray diffraction structures of 3 and 4. Compounds 5 and 6 showed that the butadienesulfonyl ligands are coordinated through the sulfur atoms and the terminal double bonds, according to the X-ray study of compound 5 and NMR spectroscopy. Immediate formation of compound 5 can be achieved in 83% yield from [Cp*IrCl 2 ] 2 and 1K, showing that the alkaline metal is crucial in the isolation of the lithium derivatives 3 and 4.

Steps and the surface dissociation of metal dimers: Direct observations on Ir(111)

Lattice steps on metal surfaces are known to enhance the dissociation rate of diatomic gases and also of large metal clusters. To establish the effectiveness of steps in promoting dissociation of metal dimers, we use the field ion microscope to compare the behavior of individual iridium dimers ${\mathrm{Ir}}_{2}$ on the close-packed (111) plane of iridium with that at lattice steps bounding this plane. On the perfect (111) plane, dissociation takes place at \ensuremath{\sim}250 K; at sites at lattice steps, either of type A or B, dissociation occurs under similar conditions but at a rate three times faster than at interior sites.

Pyrazolyl-bridged iridium dimers. 18.(1) influence of metal-metal bonding on the geometry of diiridium(II) adducts and hydrido-diiridium complexes formed from the diiridium(I) prototype [Ir(mu-pz)(PPh(3))(CO)](2) (pzH = Pyrazole) by dihydrogen addition or protonation.

Slow uptake of molecular dihydrogen by the diiridium(I) prototype [Ir(mu-pz)(PPh(3))(CO)](2) (1: pzH = pyrazole) is accompanied by formation of a 1,2-dihydrido-diiridium(II) adduct [IrH(mu-pz)(PPh(3))(CO)](2) (2), for which an X-ray crystal structure determination reveals that (unlike in 1) the PPh(3) ligands are axial, with the hydrides occupying trans coequatorial positions across the Ir-Ir bond (2.672 A). Reaction with CCl(4) effects hydride replacement in 2, affording the monohydride Ir(2)H(Cl)(mu-pz)(2)(PPh(3))(2)(CO)(2) (3) in which Ir-Ir = 2.683 A. At one metal center, H is equatorial and PPh(3) is axial, while at the other, Cl is axial as is found in the symmetrically substituted product [Ir(mu-pz)(PPh(3))(CO)Cl](2) (4) (Ir-Ir = 2.754 A) that is formed by action of CCl(4) on 1. Treatment of 1 with I(2) yields the diiodo analogue 5 of 4, which reacts with LiAlH(4) to afford the isomorph Ir(2)H(I)(mu-pz)(2)(PPh(3))(2)(CO)(2) (6) of 3 (Ir-Ir = 2.684 A). Protonation (using HBF(4)) of 1 results in formation of the binuclear cation Ir(2)H(mu-pz)(2)(PPh(3))(2)(CO)(2)(+) (7: BF(4)(-) salt), which shows definitive evidence (from NMR) for a terminally bound hydride in solution (CH(2)Cl(2) or THF), but 7 crystallizes as an axially symmetric unit in which Ir-Ir = 2.834 A. Reaction of 7 with water or wet methanol leads to isolation of the cationic diiridium(III) products [Ir(2)H(2)(mu-OX)(mu-pz)(2)(PPh(3))(2)(CO)(2)]BF(4) (8, X = H; 9, X = Me).

Labile Hydrido Complexes of Iridium(III): Synthesis, Dynamic Behavior in Solution, and Reactivity toward Alkenes

The trisacetonitrile complexes [IrClH(PiPr3)(NCCH3)3]BF4 (1) and [IrH2(PiPr3)(NCCH3)3]BF4 (2) have been prepared in one-pot reactions with high yields by reaction of the iridium(I) dimers [Ir(μ-Cl)(coe)2]2 and [Ir(μ-OMe)(cod)2]2 with the phosphonium salt [HPiPr3]BF4. The rates of exchange between free acetonitrile and the labile acetonitrile ligands of complexes 1 and 2 have been measured by NMR spectroscopy. This kinetic study has shown that both complexes readily dissociate one acetonitrile ligand trans to hydride, giving rise to fluxional five-coordinate intermediates. Substitution products 3−7 have been obtained by treatment of complexes 1 and 2 with CO and PMe3. The structures determined for 3−7 can be rationalized on the basis of the steric requirements of the ligands, indicating that the products are formed by thermodynamic control. Ethene inserts reversibly into the Ir−H bond of 1 to give the compound [IrCl(Et)(PiPr3)(NCCH3)3]BF4 (8), which has been used for the preparation of the stable ethyliridium(III) complexes [IrCl(Et)(PiPr3)(Py)2(NCCH3)]BF4 (9) and [Ir(η2-O2CCH3)Cl(Et)(PiPr3)(NCCH3)3] (10), respectively. The molecular structure of 10 has been determined by X-ray crystallography. The reaction of 2 with ethene, at low temperature, results in the sequential formation of the ethene complex [IrH2(η2-C2H4)(PiPr3)(NCCH3)2]BF4 (11) and the diethyl derivative [Ir(Et)2(PiPr3)(NCCH3)3]BF4 (14). At room temperature in solution, 14 undergoes reductive elimination of ethane to form the iridium(I) species [Ir(PiPr3)(NCCH3)3]BF4 (15) and [Ir(PiPr3)(η2-C2H4)(NCCH3)2]BF4 (16). These cations readily react with H2 to regenerate 2, closing a cycle for ethene hydrogenation in which several participating species have been identified. The reaction of 2 with propene in solution also allows the characterization of products of propene coordination (17) and insertion (18). In this case, the species obtained after elimination of propane are products of allylic C−H activation: [IrH(η3-C3H5)(PiPr3)(NCCH3)2]BF4 (19) and [IrH(η3-C3H5)(η2-C3H6)(PiPr3)(NCCH3)]BF4 (20). The structure of complex 19 has been determined by X-ray diffraction, and the kinetics of dissociation of its two labile acetonitrile ligands have been studied by NMR spectroscopy. Complex 19 undergoes electrophilic activation of H2 to give propene and reform the starting complex 2.

Heterobimetallic Indenyl Complexes. Synthesis and Carbonylation Reaction of anti-[Cr(CO)3-μ,η:η-indenyl-Ir(COD)

The reaction of the anti-[Cr(CO)3-μ,η:η-indenyl-Ir(COD)] (I) complex with an excess of CO in CH2Cl2 at 203 K produces quantitatively the η1-[η6-Cr(CO)3-indenyl]-Ir(COD)(CO)2 intermediate which above 273 K converts into the fully carbonylated complex η1-[η6-Cr(CO)3-indenyl]Ir(CO)4; this in turn is stable up to 313 K. Carbonylation of the anti-[Cr(CO)3-μ,η:η-indenyl-Ir(COE)2] analogue (II) gives the η1-[η6-Cr(CO)3-indenyl]-Ir(CO)4 (VII) species in a single fast step. In contrast to the behavior of the corresponding rhodium complexes, for which η1 intermediates have never been observed and the aromatized substitution product is the stable product, the rearomatization of the cyclopentadienyl ring in iridium complexes to give the “normal” substitution product, viz., anti-[Cr(CO)3-μ,η:η-indenyl-Ir(CO)2] (III) is a difficult process which takes place only on bubbling argon through the solution. The final product III is barely stable in solution. If the carbonylation is carried out using a blanket of CO over the solution of complexes I and II, viz., failing CO, the scarcely soluble iridium dimer [η6-Cr(CO)3-indenyl-η3-Ir(CO)3]2 (IX) stable in the solid state is obtained, probably by dimerization of the unstable intermediate anti-[η6-Cr(CO)3-indenyl-η3-Ir(CO)3] (X).

Theoretical studies on hydrogen activation by iridium dimers

The basic and fundamental mechanisms governing the catalytic reaction of small iridium clusters with H2 are presented here with the purpose to determine its behavior in hydrogenation reactions. The iridium dimer/s lowest states in interaction with H2 potential energy surface were obtained using ab initio multiconfigurational self-consistent-field calculations (MC–SCF), with relativististic pseudopotentials. The electronic correlation contribution was included by configurations interaction (CI) calculations, which considered a variational part plus a second-order perturbative part. The Ir2+H2 reactions were developed in the C2v symmetry. The Ir2's five lowest electronic states were determined, 5Πg, 3Πg, 1Σg+, 3Σu+, and 5Σg, and studied when reacted with H2. It was found that the iridium dimer, in these five states, might capture and break the HH bond, spontaneously in certain cases and after surmounting activation barriers in other cases. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 1029–1035, 1998

Theoretical studies on hydrogen activation by iridium dimers

Theoretical studies on hydrogen activation by iridium dimers

Temperature and Isotope Effects on the Rates of Photoinduced Iridium(I)−Pyridinium Electron-Transfer Reactions

Intramolecular electron-transfer (ET) rates have been measured as functions of reaction driving force (0.0−2.0 eV) and temperature (200−280 K) for a series of iridium dimers (Ir2) covalently bound to substituted pyridinium (py+) groups. We found that the rates of recombination reactions (py• → Ir2+) at high driving forces are strongly dependent on temperature and that Ir2* → py+ and py• → Ir2+ rates in both the normal and inverted regions are slower on deuteration of the pyridinium acceptors. Analysis of the rates in terms of semiclassical theory gives the following parameter values: HAB = 52(9) cm-1, λ = 1.05(2) eV (280 K); HAB = 22(2) cm-1, λ = 1.04(1) eV (210 K). 4-Phenyl-N-ethylpyridinium iodide, chosen as a model for the acceptors in the Ir2* → py+ reactions, exhibited resonance Raman scattering that implicated a 1565-cm-1 mode as dominant for inner-sphere reorganization.

Tris(diphenylthiophosphinoyl)methanide as tripod ligand in rhodium(III), iridium(III) and ruthenium(II) complexes. Crystal structures of [( η5-C 5Me 5)Ir{ η3-(SPPh 2) 3C-S,S′,S″}]BF 4 and [( η6-MeC 6H 4Pr i)Ru{ η3-(SPPh 2) 3C-S,S′,S″}]BPh 4

Reaction of the complex [{(η 5-C 5Me 5)RhCl 2} 2], in CH 2Cl 2 solution, with AgBF 4 (1:2 molar ratio) and (SPPh 2) 3CH leads to the cationic compound [(η 5-C 5Me 5)RhCl{η 2-(SPPh 2) 2CH(SPPh 2)-S,S′}]BF 4 ( 1) which is deprotonated by thallium(I) pyrazolate affording [(η 5-C 5Me 5)Rh{η 3-(SPPh 2) 3C−S,S′,S″}]BF 4 ( 2a). The iridium dimer [(η 5-C 5Me 5)IrCl 2} 2] reacts with silver salts and (SPPh 2) 3CH, in CH 2Cl 2 or Me 2CO, under analogous conditions, affording mixtures of [(η 5-C 5Me 5)IrCl{η 2-(SPPh 2) 2)-S,S′}] + and [(η 5-C 5Me 5)Ir{η 3-(SPPh 2) 3C-S,S′,S″}]A [A=BF 4 − ( 3a), PF 6 − ( 3b). Addition of Et 3N to the mixture gives pure complexes 3. The ruthenium complexes [{η 6j6-arene)RuCl 2} 2] (arene = C 6Me 6, p-MeC 6H 4Pr i) react with (SPPh 2) 3CH, in the presence of AgA (A = PF 6 − or BF 4 −) or Na BPh 4, in CH 2Cl 2 or Me 2CO, yielding only the deprotonated complexes [(η 6-arene)Ru{η 3-(SPPH 2) 3C−S,S′,S″}]A [arene = C 6Me 6, A = BF 4; arene = p-MeC 6H 4Pr i, A - BPh 4 ( 4a), PF 6 ( 4b)]. The crystal structures of 3a and 4a were established by X-ray crystallography. Compound 3a crystallizes in the orthorhombic space group Pna2 1, with lattice parameters a-41.477(6), b = 10.6778(11), c = 20.162(3) Å and Z=8. Complex 4a crystallizes in a monoclinic lattice, space group P2 1/ n, with a = 20.810(4), b = 12.555(3), c = 23.008(4) Å, β = 95.82(2)° and Z = 4. Both cationic complexes exhibit analogous pseudo-octahedml molecular structures with the anionic (SPPh 2) 3C − ligand bonded via the three sulphur atoms in a tripodal, tridentate fashion. Each metal centre completes its coordination environment with a η 5-C 5Me 5 ( 3a) or a η 6-MeC 6H 4Pr i group ( 4a). A quite interesting result concerns the non-planarity of the methanide carbon which display P−C−P angles in the range 112.6–114.4(5)° in 3a and 111.9–113.6(4)° in 4a. The redox chemistry of the complexes was investigated by cyclic voltammetry. The Rh(III) complexes are quasi-reversibly reduced to Rh(I) and the Ir(III) complex is irreversibly reduced to IKD in acetonitrile solutions. The Ru(II) complex undergoes a quasi-reversible reduction to Ru(I) and a reversible oxidation to Ru(III).

New Electrophilic Iridium(I) Complexes: H−H and C−H Bond Heterolysis by [(dfepe)Ir(μ-X)]2(X = O2CCF3, OTf)

New electrophilic dimeric iridium(I) complexes [(dfepe)Ir(μ-X)]2 (dfepe = (C2F5)2PCH2CH2P(C2F5)2; X = O2CCF3, OTf) have been prepared and their reactions with H2 and cyclopentane examined. Treatment of [(cod)Ir(O2CCF3)]2 with dfepe produced an ionic product [(dfepe)Ir(cod)]+[(dfepe)Ir(O2CCF3)2]- (1), which in refluxing benzene rearranged with loss of cyclooctadiene to form [(dfepe)Ir(μ-O2CCF3)]2 (2). The corresponding reaction of [(cod)Rh(O2CCF3)]2 with dfepe yielded [(dfepe)Rh(μ-O2CCF3)]2 (3) directly. X-ray diffraction analysis of 2 revealed a hinged dimeric geometry with an unusually large interplanar angle of 82.7° defined by the two 4-coordinate metal centers (Ir(1)−Ir(2) = 4.307 A). The triflate-bridged analogue of 2 was prepared via an indirect route: addition of 1 equiv of triflic acid to (dfepe)Ir(η3-C3H5) yielded the allyl hydride complex (dfepe)Ir(η3-C3H5)(H)(OTf) (4), which eliminated propylene in refluxing heptane to quantitatively afford [(dfepe)Ir(μ-O3SCF3)]2 (5). The structure of 4 was co...

Pyrazolyl-bridged iridium dimers 15. Synthesis of binuclear cyclopentadienyl Ir(III) complexes and the rhodium analogues: reductive access to the bimetal (II) state

Mononuclear M(III) complexes of formulae [ MCp ∗Cl ( 3−n( R 2pzH ) n] (n−1)+ ( M = Rh or Ir; n = 1,2) have been prepared through reactions of pyrazole (pzH, i.e. R = H) or substituted pyrazoles (R = Me or t-butyl) with rhodium and iridium cyclopentadienyl or pentamethylcyclopentadienyl precursors; for n = 1, the crystal and molecular structure has been determined by using X-ray diffraction ( 11, M = Rh, R = H, FW = 377.96 g mol −1, space group P2 1/n, a = 7.1685(7), b = 15.740(3), c = 13.407(4) A ̊ , β = 94.50(3)° ). Dinuclear complexes of formulae [M( η 5-C 5R 5)Cl( μ-pz)] 2 ( 18, M = Rh, R = H; 19, M = Rh, R = H; 21, M = Ir, R = H; 20, M = Ir, R = Me; 21, M = Ir, R = H) containing pyrazolyl bridges can be isolated through further reaction of the mononuclear compounds, or more directly from the chloro-bridged dimers [M( η 5-C 5R 5)Cl 2] 2 by treatment with pyrazole in the presence of Et 3N, although the dipyrazole iridium cation [IrCp ∗Cl(pzH) 2] + ( 16) does not undergo this type of dimerization. The dimeric complexes, which possess a ‘chair’ geometry about the 6-membered bridging heterometallocycle, have been shown to undergo a core conformational change (‘chair’: ‘boat’) upon chemical reduction or halide abstraction. Chloride abstraction from 18 yields the binuclear product [{RhCp ∗(μ-pz)} 2(μ-Cl)]BF 4 ( 23) and reduction of either 18 or the C 5H 5 analog 19 gives access to the metal-metal bonded binuclear complexes [Rh( η 5-C 5R 5)( μ-pz)] 2, 25 (R = Me) and 26 (R = H), which adopt a ‘boat’ core conformation. The reactivity of the metal-metal bonded products has been investigated: a triply-bridged single-fragment oxidative addition product resulting from reaction with H +/MeOH ({[RhCp(μ-pz)] 2(μ-OMe)}O 2CCF 3, 29) has been structurally characterized (FW = 614.2 g mol −1, space group P2 1/n, a = 12.9647(3), b = 13.805(3), c = 11.593(3) A ̊ , β = 90.44(2)°) .

Polyhydride (Fluoroalkyl)phosphine Complexes of Iridium. Synthesis, Dynamics, and Reactivity Properties of (dfepe)2Ir2(μ-H)3(H)

The synthesis and reactivity properties of new dimeric iridium polyhydrides incorporating the acceptor ligand (C2F5)2PCH2CH2(C2F5)2 (dfepe) are reported. Hydrogenolysis of (dfepe)Ir(η3-C3H5) (prepared by metathesis of [(dfepe)Ir(μ-Cl)]2 with allylmagnesium chloride) afforded (dfepe)2Ir2(μ-H)3(H) (3) in high yield as an air-stable red crystalline solid. A triply bridged ground-state geometry for 3 was deduced from low-temperature NMR data and was confirmed by X-ray crystallography. Hydride site exchange mechanisms are proposed which are consistent with VT 1H and 31P NMR data. Although 3 is formally coordinatively saturated, hydride bridge dissociation readily occurs and leads to ligand addition reactions. Thus, treatment of tetrahydride 3 with 1 atm of H2 at 20 °C quantitatively affords the hexahydride dimer [(dfepe)Ir(μ-H)2(H)2]2 (5). In the absence of H2, 5 rapidly loses H2 in solution at 20 °C to re-form 3. The structure of 5 has been determined by X-ray crystallography. 3 also reacts with CO to give (d...

Reactions of CH bonds in organica oxygenates with octaethylporphyrinato rhodium(II) and iridium(II) dimers

Metalloporphyrin dimers, [(OEP)M] 2 ( 1a , M = Rh; rm1b, M = Ir; OEP = Octaethylporphrin dianion ), are observed to react with CH bond units in aldehyes, kenotes and benzyl alohols. Aldehydes, R 2CHCHO, preferentially react at the alkyl group adjacent to the carbonyl position to yield β-formyl complexes, (OEP)M-CR 2CHO, even when reaction of the aldehydic CH unit is thermodynamically favored. Reaction at the carbon-hydrogen bond adjacent to the carbonyl group is proposed to occur by addition of the metalloporphyrin to the enol isomer to produce an intermediate alkyl bridged complex, (OEP)M-CR'(OH)-M(OEP), which subsequently reacts by an effective β-OH migration to form (OEP)M-CR 2C(O)R' and (OEP)M-H complexes. [(OEP)Rh] 2 also reacts with benzyl alcohols C 6H 5CH(OH)R (R = H, CH 3, C(O)C 6H 5), to produce intermediate α-hydroalkyl derivatives, (OEP)Rh-CR(OH)C 6H 5, which subsequently dissociate to give organic carbonyl species, C 6H[in5]C(O)R, and (OEP)Rh-H.

Structure of dicarbonylbis-(μ-3,5-dimethylpyrazolyl)-bis(4-tolyl diphenylphosphinite)diiridium(I)–dichloromethane (1/1)

In bis(μ-3,5-dimethylpyrazolyl-N:N')-bis[carbonyl( 4-tolyl diphenylphosphinite-P)iridium(I)] dichloromethane solvate, two Ir^I atoms are joined by two 3,5-dimethylpyrazolyl bridges with one carbonyl and one 4-tolyl diphenylphosphinite ligand completing the square-planar geometry about each Ir atom. The Ir· · ·Ir distance of 3.307 (1) A is greater than the distance of 3.22 A found in a similar pyrazolyl-bridged iridium(I) dimer [Fox (1989). PhD dissertation, California Institute of Technology, USA].

Reactions of bis(iminophosphoranyl)methanes with chloro-bridged rhodium or iridium dimers giving complexes in which the ligand is coordinated either as a σ-N,σ-N′ or as a σ-N, σ-C chelate. X-ray crystal structure of the σ-N, σ-N′ Rh(I) complex Rh{(4-CH 3-C 6H 4-NPPh 2) 2CH 2}(COD)]PF 6

Bridge splitting reactions of [ML 2CI] 2 (M  Rh, Ir; L 2COD, NBD; LCO) with bis-iminophos- phoranylmethanes CH 2(PPh 2NR) 2 (bipm, I) lead to Rh(I) and Ir(I) complexes with N,N′ as well as N,C bidentate coordinated bipm: [ML 2{(4-R′-C 6H 4-NPPh 2) 2CH 2}] +X - ( II) and [ML 2{(4-R′- C 6H 4-NH-PPh 2)CH(PPh 2N-C 6H 4-R′-4)}] +X - ( III; R′ CH 3, NO 2 OCH 3; X  CI, MCl 2L 2, BF 4, PF 6). The ratio II: III depends on the metal, the bipm ligand I, the solvent and the presence of silver(I) or sodium salts. In the N,C coordinated bipm, a tautomeric 1,3-H shift from carbon to the pendant nitrogen atom has taken place. The X-ray crystal structure of [Rh{(4-CH 3- C 6H 4-NPPh 2) 2CH 2}(COD)]PF 6 has been solved. Space group P2 1/ c, monoclinic, a=21.832(9), b = 22.349(6), c = 12.001(6) Å, β=100.28(3)° , Z=4. Refinement of 4071 observed reflections converged to R = 0.087. The structure comprises a distorted square planar Rh(I) environment where the coordination positions are taken by COD and the two nitrogen atoms of the bipm ligand. The six-membered RhNPCPNRh metallacycle has a distorted boat conformation. Synthesis and spectroscopic data of the pure complexes II and III are described. The formation of the complexes and the influence of the reaction parameters on the ratio II: III are discussed.

Intramolecular Electron Transfer in Iridium Dimers

Abstract The kinetics of photoinduced electron transfer and thermal recombination have been measured in a series of covalently linked donor-acceptor complexes. The molecules are based on pyrazolate-bridged iridium(I) dimers with pyridinium groups covalently bound to terminal phosphinite ligands. The driving-force dependence of the electron-transfer kinetics in one series agrees well with the predictions of the classical theory of electron transfer. The donor-acceptor electronic coupling, however, exhibits a sensitive and unexpected dependence on the nature of the bridge between the redox partners.

Gaussian Free-Energy Dependence of Electron-Transfer Rates in Iridium Complexes

The kinetics of photoinduced electron-transfer (ET) reactions have been measured in a series of synthetic donor-acceptor complexes. The electron donors are singlet or triplet excited iridium(I) dimers (Ir(2)), and the acceptors are N-alkylpyridinium groups covalently bound to phosphinite ligands on the Ir(2) core. Rate constants for excited-state ET range from 3.5 x 10(6) to 1.1 x 10(11) per second, and thermal back ET (pyridinium radical to Ir(2)(+)) rates vary from 2.0 x 10(10) to 6.7 x 10(7) per second. The variation of these rates with driving force is in remarkably good agreement with the Marcus theory prediction of a Gaussian free-energy dependence.

Pyrazolyl-bridged iridium dimers. 14. Steric control in ground-state oxidative addition of methyl iodide to complexes related to tetracarbonylbis(.mu.-pyrazolyl)diiridium

Pyrazolyl-bridged iridium dimers. 14. Steric control in ground-state oxidative addition of methyl iodide to complexes related to tetracarbonylbis(.mu.-pyrazolyl)diiridium

ChemInform Abstract: Oxidation of Hexaaquairidium(III) and Related Studies: Preparation and Properties of Iridium(III), Iridium(IV), and Iridium(V) Dimers as Aqua Ions.

AbstractElectrochemical or chemical (Ce(IV)) oxidation of Ir(H2O)63+ in acidic solution gives a brown‐green product that titrates for Ir(V).

Oxidation of hexaaquairidium(III) and related studies: preparation and properties of iridium(III), iridium(IV), and iridium(V) dimers as aqua ions

Oxydation electrochimique ou par le Ce(IV), de l'espece [Ir(H 2 O) 6 ] 3+ . Obtention de complexes dimeres du type [(H 2 O) 4 Ir(OH) 2 Ir(H 2 O) 4 ] n+ . Caracterisation par la spectrometrie RMN et UV visible