CO Bridges Research Articles

Investigation of the behaviour of a Pd/γ-Al 2O 3 catalyst during methane combustion reaction using in situ DRIFT spectroscopy

In situ and/or operando DRIFT spectroscopy was applied to the study of the behaviour of a Pd (2 wt.%)/γ-Al 2O 3 catalyst, used in methane combustion, under various conditions. Under conventional O 2-rich reaction conditions, spectator species (carbonates and/or formates) could be observed, but no surface intermediate species. No differences were observed under reaction conditions in function of the initial oxidation state of palladium. Formates/carbonates species were identified at low temperature (<400 °C) and disappeared when CO 2 production started. They are not involved in the overall reaction pathway of methane oxidation and are thus suggested to be spectator species. Their production requires a continuous source of CO and would come from the interaction of CO with OH-groups of the γ-alumina support. Under O 2-lean (O 2/CH 4 = 2) conditions, CO bridging on metallic palladium ( P d x 0 – CO ) is observed at high temperature (>400 °C), evidencing incomplete oxidation of methane. Based on previous operando Raman studies, a mechanistic scheme is proposed, which takes into account the various surface phenomena observed.

Organometallic Nickelamacrocycles of the Type [(R2R‘P)Ni(C2H4COO)]n: Synthesis and Self-Assembly to Form Different Molecular Architectures Tuned by the Phosphine

The reaction of succinic anhydride with a 1:2 mixture of (cod)2Ni and a monodentate phosphine generates reactive monomeric nickelalactones, which undergo rapid aggregation to form cyclic oligomers of the composition [(R2R‘P)Ni(C2H4COO)]n (R2R‘P = EtPh2P (2), Me3P (4), (i-Pr)3P (5), Cy3P (6), Et3P (7)). The complexes were fully characterized by elemental analyses (except 4), NMR and IR spectroscopy, and X-ray crystallography of single crystals. Depending on the bulkiness of the phosphines, three types of nickelamacrocycles with different ring size and different connectivity pattern of the monomeric units are formed. The small Me3P stabilizes a cyclic tetramer (n = 4) in which the units are linked by Ni−O−Ni bonds. This bridge is stable in thf solution. The bulkiest phosphines stabilize another type of cyclotetrameric architecture in 2, 5, and 6, in which the monomeric units are connected by Ni−O−CO bridges. In contrast, 7, stabilized by the Et3P ligand, forms a hexacyclic compound (n = 6) with Ni−O−CO bridges. The IR spectrum of 7 in thf shows two CO valence frequencies, indicating that at least two species are present in which the carboxylate group is differently coordinated (Ni−O and Ni−O−CO−Ni coordination).

Lanthanide-transition-metal carbonyl complexes: new [Co4(CO)11]2- clusters and lanthanide(II) isocarbonyl polymeric arrays.

Two types of Ln(II)-Co(4) isocarbonyl polymeric arrays, [(Et(2)O)(3)(-)(x)()(THF)(x)()Ln[Co(4)(CO)(11)]]( infinity ) (1-3; x = 0, 1) and [(THF)(5)Eu[Co(4)(CO)(11)]]( infinity ) (4), were prepared and structurally characterized. Transmetalation involving Ln(0) and Hg[Co(CO)(4)](2) in Et(2)O yields [(Et(2)O)(3)Ln[Co(4)(CO)(11)]]( infinity ) (1, Ln = Yb; 2, Ln = Eu). Dissolution of the solvent-separated ion pairs [Ln(THF)(x)()][Co(CO)(4)](2) (Ln = Yb, x = 6; Ln = Eu) in Et(2)O affords [(Et(2)O)(2)(THF)Yb[Co(4)(CO)(11)]]( infinity ) (3) and [(THF)(5)Eu[Co(4)(CO)(11)]]( infinity ) (4). In these reactions, oxidation and condensation of the [Co(CO)(4)](-) anions result in formation of the new tetrahedral cluster [Co(4)(CO)(11)](2)(-). The two types of Ln(II)-Co(4) compounds contain different isomers of [Co(4)(CO)(11)](2)(-), and, consequently, the structures of the infinite isocarbonyl networks are distinct. The cluster in [(Et(2)O)(3)(-)(x)()(THF)(x)()Ln[Co(4)(CO)(11)]]( infinity ) (1-3) possesses pseudo C(3)(v)() symmetry (an apical Co, three basal Co atoms; one face-bridging, three edge-bridging, seven terminal carbonyls) and connects to Ln(II) centers through eta(2),micro(4)- and eta(2),micro(3)-carbonyls to generate a 2-D puckered sheet. In contrast, [(THF)(5)Eu[Co(4)(CO)(11)]]( infinity ) (4) incorporates a C(2)(v)() symmetric cluster (two unique Co environments; two face-bridging, one edge-bridging, eight terminal carbonyls), and isocarbonyl linkages (eta(2),micro(4)-carbonyls) to Eu(II) atoms create a 1-D zigzag chain. Complexes 1-4 contain the first reported eta(2),micro(4)-CO bridges between a Ln and a transition-metal carbonyl cluster. Infrared spectroscopic studies revealed that the isocarbonyl associations to Ln(II) persist in solution. The solution structure and dynamic behavior of the [Co(4)(CO)(11)](2)(-) cluster in 1 was investigated by variable-temperature (59)Co and (13)C NMR spectroscopies.

Molecular Gas and the Nuclear Star Cluster in IC 342: Sufficient Inflow for Recurring Star Formation Events?

We present high spatial resolution (12) millimeter-interferometric observations of the 12CO (2-1) line emission in the central 300 pc of the late-type spiral galaxy IC 342. The data, obtained with the Owens Valley Radio Observatory, allow first-time detection of a molecular gas disk that coincides with the luminous young stellar cluster in the nucleus of IC 342. The nuclear CO disk has a diameter of ~30 pc and a molecular gas mass of M ~ 2 × 105 M☉. It connects via two faint CO bridges to the well-known 100 pc diameter circumnuclear gas ring. Analysis of the gas kinematics shows that the line of nodes in the inner 15 pc is offset by about 45° from the major kinematic axis, indicating noncircular motion of the gas within a few parsecs of the dynamical center of IC 342. Both the morphology and the kinematics of the CO gas indicate ongoing inflow of molecular gas into the central few parsecs of IC 342. We infer a gas inflow rate between 0.003 and 0.14 M☉ yr-1, based on the observed surface density of the nuclear gas disk and estimates of the radial velocities of the surrounding gas. Inflow rates of this order can support repetitive star formation events in the nucleus of IC 342 on timescales much smaller than a Hubble time.

Intramolecular Conformational Control in Ferrocenes Bearing Podand Dipeptide Chains

Ferrocenes bearing podand dipeptide chains were demonstrated to induce intramolecular conformational regulation through hydrogen bondings. The single-crystal X-ray structure determination of the ferrocene bearing the podand dipeptide chains -Gly-l-Pro-OEt confirmed the formation of two intramolecular interchain hydrogen bondings between CO (Gly) and NH (another Gly) of each podand dipeptide chain (N(1)···O(102), 2.910 A; N(101)···O(2), 2.898 A; N(201)···O(302), 2.85 A; N(301)···O(202), 2.87 A) to give a 10-membered hydrogen-bonded ring. The ferrocene bearing the podand dipeptide chains -l-Pro-Gly-OEt is also considered to form two rigid intramolecular interchain hydrogen bondings between CO (bridging) and NH (another Gly) to give a 14-membered hydrogen-bonded ring. Such an ordered conformation was supported by the induced circular dichroism. On the other hand, the ferrocene bearing one dipeptide chain -Gly-l-Pro-OEt is packed in a helically ordered arrangement with one turn of 15.65 A pitch height through...

Mobility and Clustering of Rh and Ru in Zeolite. Experiment and Theory

Ruthenium and rhodium have been atomically dispersed on Na zeolite as shown by the infrared spectra of RhI(CO)2 and RuI(CO)2 produced upon reduction in a CO atmosphere. Formation of adsorbed CO bridging two Rh(I) surface atoms upon partial removal of adsorbed CO indicates some Rh(I) species can occupy adjacent surface sites contrary to suppositions in most current literature. While Rh(I) surface species seem to be relatively immobile below 100 °C, our data suggest that Rh0 surface atoms are mobile to some extent. Self-consistent field density functional calculations have been performed for several surface clusters; they indicate that Rh−surface bonds are much weaker for Rh0 species than for Rh(I) species. These calculations support the proposition that Rh0 surface species are more mobile than Rh(I) surface species.

Dissociative kinetics of ‘lightly bonded ligands’ L from the clusters Rh 6(CO) 15L ( L = DMSO, NCMe, cyclooctene, THF and EtOH)

The kinetics of displacement of some ‘lightly bonded ligands’, L, ( L = dimethylsulfoxide (DMSO), NCMe, cyclooctene, tetrahydrofuran and EtOH) from Rh 6(CO) 15 L in CHCl 3 or CH 2Cl 2 by P(OPh) 3 have been investigated. Mass law retardation shows that the reactions are stoichiometrically dissociative and proceed via a {Rh 6(CO) 15} intermediate that could be stabilized by the entry of solvent into the vacant coordination site or by extra CO bridging. The limiting rate constants, k 1, increase by ca. 10 5 along the series listed above ( t 1/2 values decrease from ≈100 s to 1 ms at 25°C). A plot of log k 1 versus log k rel ( k rel = relative equilibrium constants for the reactions) is linear with a gradient of 0.87 ± 0.05 which indicates high degrees of Rh- L bond breaking in the transition states. The low values of Δ S ‡ for L = DMSO and NCMe (−4.5 ± 4.4 and 17 ± 12 J K −1 mol −1, respectively) suggest that the slower reactions may require some stabilization of the developing {Rh6(CO) 15} moiety by transition state solvation or extra CO bridging. This stabilization could amount to as much as 30 kJ mol −1 for L = DMSO. Relative rates of reactions of P-donors with the intermediate {Rh 6(CO) 15} suggest that these reactions are I d in character. Reactions with Bu 4NBr show that Br − is much more nucleophilic towards {Rh 6(CO) 15} than the neutral nucleophiles and that the nucleophilicity of the ion pair Bu 4N +Br − is coincidentally similar to that of the P-donors because pronounced Rh-Br − bond making is offset by the attraction due to the cation.

Synthesis and characterization of poly(ether ketone)/poly(ether sulfone) alternating and sequential copolymers by electrophilic reactions

AbstractThe synthesis and NMR characterization of some poly(ether ketone)/poly(ether sulfone) (PEK/PES) alternating copolymers together with a series of sequential homopolymers containing CO, O, S and SO2 bridging groups, all obtained by electrophilic condensation reactions using phosphorus pentoxide/methanesulfonic acid as dehydrating agent, is here reported. Properties of such polymers are compared with those of their model compounds from which it can be inferred that both proton and carbon chemical shifts are very sensitive to the electronic environment generated by the O, S, CO and SO2 bridges. Differential scanning calorimetry indicates that our polymers are essentially amorphous irrespective of the bridging sequence. From viscosity measurements the molecular weights of these copolymers are judged to be very low.

Metallorganische Verbindungen des Iridiums und Rhodiums: XXXI. Heterobimetallische Zweikern-Komplexe durch Addition von Cp(CO) 3 MH (M  Mo, W) an Ir(CH 3)(CO)(PPh 3) 2

Treatment of Ir(CH 3)(CO)(PPh 3) 2 with molybdenum or tungsten hydrides Cp(CO) 3MH results in elimination of both CH 4 and CO to give heterobimetallic products of composition Cp(CO) M(μ-CO) 2-I r(PPh 3) 2 ( 1: M  Mo; 2: M  W). Degradation of these complexes in solution occurs by CO transfer and oxidative PC addition, affording the phosphido-bridged derivatives Cp(CO) 2- M(μ-Ph 2P)I r(C 6H 5)(CO) 2(PPh 3) ( 3: M  Mo; 4: M  W) as the ultimately stable compounds. The structures of 1 and 2, determined by X-ray crystallography, comprise Cp (CO) 3M groups attached to the Ir(PPh 3) 2 mioiety by short metal-metal bonds (MoIr 2.579(1), WIr 2.583(1) Å) and two asymmetric CO bridges.

Intramolecular Dynamics of Tetranuclear Iridium Carbonyl Cluster Compounds. Part IV. Derivatives with monodentate ligands and edge‐bridging bidentate ligands

AbstractThe fluxionality of [Ir4(CO)8(μ2‐CO)3L] (L = Br−, I−, SCN−, NO2−, P(4‐ClC6H4)3, PPh3, P(4‐MeOC6H4)3, P(4‐Me2NC6H4)3), as studied by 2D‐13C‐NMR in solution, is due to two successive scrambling processes: the merry‐go‐round of six basal CO's and CO bridging to alternative faces of the Ir4 tetrahedron. The basicity of the ligand L has no significant effect on the activation parameters. The scrambling process of lowest activation energy in [Ir4(CO)7(μ2‐CO)3(PMePh2)2] correspond to the two possible synchronous CO bridging about a unique face of the metal tetrahedron swapping the relative axial and radial positions of the ligands L. The disubstituted clusters [Ir4(CO)10(μ2‐LL)] with one edge‐bridging ligand have a ground‐state geometry with three edge‐bridging CO's (LL = bis(diphenylphosphino)methane, bis(diphenylarsino)methane, bis(diphenylphosphino)propane) or with all terminal CO's (LL = CH3SCH2SCH3). In all cases, the fluxional process of lowest activation energy in the merry‐go‐round of six CO's about a unique triangular face. For the P and As donor ligands, this process is followed by the rotation of terminal CO's bonded to two Ir‐atoms residing on the mirror plane of the unbridged intermediate.

Kinetics and mechanism of CO substitution reactions of M 3(CO) 12 (MFe, Ru, Os) in the presence of ( p-CH 3OC 6H 4) 2TeO

The rates and activation parameters for CO substitution of M 3(CO) 12 (MFe, Ru, Os) in the presence of ( p-CH 3OC 6H 4) 2TeO are reported. The rates are first-order in concentrations of M 3(CO) 12 and telluroxide, and zero-order in entering ligand. The Δ H‡ values for these reactions vary from 11 to 14 kcal/mol, with Δ S‡ values changing between −12 and −22 cal/mol K. The reactivities of M 3(CO) 12 towards R 2TeO decrease in the order Fe > Ru > Os. A mechanism was proposed in which the rate-determining step involves nucleophilic attack of the O atom of R 2TeO at a C atom of a carbonyl group. This is then followed by O atom transfer to form the good leaving group CO 2 and a reactive intermediate which readily reacts with the entering ligand to afford the formation of monosubstituted products. Compared with similar reactions of (CH 3) 3NO, the R 2TeO reagent has greater O atom transfer selectivity towards M 3(CO) 12 complexes. This is discussed in terms of CO bridging effects in the reaction transition states.

Kinetics and mechamisms of CO substitution of M 4(CO) 11L(M = Co, Ir; L = PPh 3 P nBu 3, P(OMe) 3, P(OEt) 3) with L in the presence of the Me 3NO

Reported are rates of CO substitution by L of M 4(CO) 11L(M = Co, Ir; L = PPh 3, P nBu 3, P(OMe) 3, P(OEt) 3) in the presence of added Me 3NO. The rate law is the same as that found earlier on such reactions, being first-order in the concentrations of metal carbonyl and of Me 3NO but zero-order in ligand concentration. The Ir compounds react from 2 to 7 times faster than do the corresponding Co compounds, and for each the rates of reaction with changes in ligand decrease in the order P(OMe) 3> P(OEt) 3> P nBu 3. The results are compared with earlier studies in the M 3(CO) 12 and M 3(CO) 11L (M = Fe, Ru, Os) clusters, where it was found that the reactivities decrease in the order Fe > Ru > Os. That this order differs from that now reported (Co < Ir) for the M 4(CO) 11L clusters is discussed in terms of the presumed important contribution of CO bridging to the rates of associative reactions in metal carbonyl clusters.

Transition metal bonding functions and their applications in catalytic adsorptions and reactions: Part IV. Characterization of CO adsorption - bonding, IR spectra, surface species population and adsorption heats

Calculations of metal bonding functions show that the controlling factors for forming end-on monocarbonyl, bridge-on carbonyl and three-fold sites on carbonyl are their corresponding functions AB, A 2B 2 and A 3B 3, respectively. A 2B 2 = 2A sB s cosα. A 3B 3 = A 2B 2 + AB when the terminal CO adsorbs on the sublayer metal atom. A and A s represent the various vacant s and d orbitais of metal M.O. bands which accept electrons from the CO 5σ and CO 1π M.O.s to form end-on and side-on σ bonds, respectively. B and B s represent the occupied d orbitais which back-donate d electrons to that part of the CO 2π M.O. located near the terminal carbon and that part of the CO 2π M.O. located on the side of the CO axis, to form end-on and side-on π bonds, respectively. α is the angle between the CO bridging bond and the CO side-on bond. Using the above metal bonding functions, it is possible to demonstrate the following experimental facts: (1) Among the Group VIII metals, excepting Pd, A s is large than A, and the value of A 3B 3 or A 2B 2 is significantly larger than AB; thus at room temperature the multi-site carbonyls prevail on Pd, whereas the end-on monocarbonyls are predominant on most Group VIII metals except Pd. (2) On Ni, the sequence of bonding functions is: A 3B 3 > AB > A 2B 2. Thus at low CO exposures, the three-fold site carbonyl begins to form on Ni(111), whereas the end-on monocarbonyl begins to form on Ni(100), since Ni(100) has no appropriate sublayer atom for forming the three-fold site bonding. (3) The end-on monocarbonyl prevails on Rh(111) and Pt(111) at low CO exposures, because in the neutral state AB > A 2B 2. But if the values of B/A and B s/A s on Rh and Pt are large, the metal is induced to a positive valence after CO adsorption, resulting in A 2B 2 > AB, which is why the bridge-on species begin to form on Rh and Pt at intermediate coverages. (4) On Ru, AB is significantly larger than A 2B 2 at a valence state between 0 and +0.5; thus Ru is totally different from Pd, Ni, Rh and Pt, and only a single peak of end-on carbonyl is present at all coverages. (5) The metal bonding functions semiquantitatively characterize the populations of various carbonyl structures on the surface and can be used to estimate adsorption heats on Group VIII metals.

A new insight from qualitative MO theory into the problem of the FeFe bond in Fe 2(CO) 9

A revision of EHMO calculations with FMO analysis has provided new qualitative insight into the bonding network in Fe 2(CO) 9 and reconciled the previous diverging interpretations. After separation of all of the Fe(CO) bridge bonding/antibonding levels (12 electrons for six FeC bonds) there remains a two-electron/two-orbital interaction (σ/σ ★) that is ultimately responsible for a direct (through-space) FeFe bond. However, predominant repulsive interactions via the CO bridges (through-bond) may hide the linkage.

Intermediates in the time-resolved and matrix photochemistry of (.eta.5-cyclopentadienyl)rhodium complexes. Roles of alkane activation and rhodium-rhodium bond formation

Pulsed laser photolysis studies of solutions of Cp{sub 2}Rh{sub 2}(CO){sub 3}, CpRh(CO){sub 2}, and CpRh(C{sub 2}H{sub 4})CO (Cp = {eta}{sup 5}-C{sub 5}H{sub 5}) are reported using UV/vis and IR detection. Isotopic labeling and polarized photolysis demonstrates that the Rh{sub 2}(CO){sub 2} unit is planar with CO bridges perpendicular to the RhRh axis. Metal-metal bond fission of Cp{sub 2}Rh{sub 2}(CO){sub 3} is observed only in CO-doped matrices. The major photoproduct of Cp{sub 2}Rh{sub 2}(CO){sub 3} in solution is (CpRh({mu}-CO)){sub 2}, which reacts with CO to re-form starting material. The first observable product of photolysis of CpRh(CO){sub 2} in cyclohexane at room temperature is CpRh(CO)(C{sub 6}H{sub 11})H, formed by insertion of CpRhCO into the solvent C-H bonds within 400 ns. The IR experiments show that photolysis of CpRh(C{sub 2}H{sub 4})CO gives a higher yield of CpRh(CO)(C{sub 6}H{sub 11})H than that from CpRh(CO){sub 2}.

Reactivity of binuclear pyrazolate-bridged rhodium complexes with isocyanides. Molecular structure of [Rh2(µ-pz)I2(CNBut)2–(µ-Ph2PCH2PPh2)2]BF4(pz = pyrazolate)

The CO groups of [Rh2(µ-pz)I2(CO)2(µ-dppm)2]ClO4(pz = pyrazolate, dppm = Ph2PCH2PPh2) have been gradually substituted by reaction with isocyanides CNR (R = But or C6H4Me-p) to give [(OC)IRh(µ-pz)(µ-dppm)2Rhl(CNR)]ClO4[R = But(3) or C6H4Me-p(4)]via[(OC)IRh(µ-pz)(µ-CO)(µ-dppm)2Rhl(CNR)]ClO4[R = But(1) or C6H4Me-p(2)] and, finally, [Rh2(µ-pz)I2(CNR)2(µ-dppm)2] ClO4[R = But(7) or C6H4,Me-p(8)]via[Rh2(µ-pz)I2(µ-CO)(CNR)2(µ-dppm)2]ClO4[R = But(5) or C6H4Me-p(6)]. The CO bridging groups of (1), (2), (5), and (6) are ketonic carbonyls according to their spectroscopic properties. The reactivity of [Rh2(µ-pz) I2(CO)2(µ-dpam)2]ClO4(dpam = Ph2AsCH2AsPh2) with isocyanides was studied for comparison. The structure of the BF4–analogue of (7), [Rh2(µ-pz)I2(CNBut)2(µ-dppm)2]BF4(7b), has been determined by X-ray diffraction methods. Crystals are monoclinic, space group P21/n with unit-cell parameters a= 20.347(8), b= 21.221(8), c= 14.514(6)A, β= 94.11(2)°, and Z= 4. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by block-matrix least squares to R= 0.0630 for 4 969 observed reflections. In the cationic complex the two Rh atoms, at a distance of 2.829(3)A, are connected by a triple bridge, involving two dppm ligands and the pyrazolate anion.

Hydrogen bonds involving CO bridging groups in cyclopentadienyl iron dicarbonyl dimer

1. Using the example of the complex [η5-C5H5Fe(CO)2]2, it has been shown that the bridging carbonyl groups are able to form hydrogen bonds with donor protons. 2. Protonation of the complex [η5-C5H5Fe(CO)2]2 has been detected in its reaction with perfluoro-tert-butanol and with HCl at the metal-metal bond in solution in liquid xenon.

Nmr studies on complex formation of poly(L‐lysine HBr) with carbonate ion in aqueous solution

AbstractDiemer formation of poly(L‐lysine HBr) in carbonate buffer at pD 10.5 was reported in our previous paper [Biopolymers(1981) 20, 345–357]. The mechanism of the dimer formation was investigated employing carbon‐13 and proton nmr. pD dependence of the 13C‐nmr spectrum of poly(L‐lysine HBr) in the presence of carbonate ion clearly shows that a complex formation between the CO ion and protonated ε‐amino group is involved in the stabilization of the dimer form. The lifetime of the complex is longer than 10−2 s. A stoichiometric evaluation suggests that CO bridges two lysyl side chains. A molecular model of the dimer form designated as a single antiparallel β‐ribbon was proposed and discussed in the light of hydrodynamic and ir spectroscopic properties reported earlier. Concentration change experiments indicate that CO binds not only to the dimer formation is inferred as stabilization of the single antiparallel β‐ribbon as an intermediate structure in the conversion between the α‐helix and β‐sheet. The α‐CH proton signal of the lysine residue located in the ordered structure (α‐helix and β‐form) was observed to be separate from that in the random‐coil region.

Preparation and nuclear magnetic resonance study of salts of the platinum(I) anions [Pt2X4(CO)2]2–(X = Cl, Br, or I)

Reactions of the anions [PtX3(CO)]–(X = Cl, Br, or I) with controlled amounts of formic acid and tri-n-propylamine in tetrahydrofuran lead to high yields of salts of [Pt2X4(CO)2]2– if appropriate cations are chosen. For Cl and Br derivatives with 13C-enriched CO (75%)195Pt and 13C n.m.r. studies are reported and values of 1J(PtPt) established. At 300 K there is exchange of CO between adjacent platinum atoms. Studies of 195Pt Fourier-transform n.m.r. spectra of the mixed halide species [Pt2XnY4–n(CO)2]2–(X,Y = Cl,Br; Cl,I; or Br,I) are interpreted on the basis of a marked preference for isomers with the higher atomic number halide on the Pt–Pt axis. For the Cl,Br system comparison between spectra obtained at 220 and at 300 K shows that at the higher temperature halide site exchange occurs on a given Pt atom, but is synchronised between both Pt atoms in the anion; this is interpreted in terms of the interplatinum atom exchange of the CO groups via CO bridging. Studies of the mixed halide species derived from [PtX3(CO)]– establish 195Pt shifts for fourteen of the eighteen possible species, and show that species with lower atomic number halide trans to CO are preferred.

Ligand effects on CO bridging in binuclear manganese carbonyl complexes

Ligand effects on CO bridging in binuclear manganese carbonyl complexes