The synthesis and reactivity of electrophilic iridium (III) complexes containing bis (diphenylphosphino) ethane

The complex Ir(CH₃) (CO) (CF₃SO₃)₂ (dppe) (1) has been synthesized from the reaction of Ir(CH₃)I₂(CO) (dppe) and silver triflate. Methane and IrH(CO) (CF₃SO₃)₂ (dppe) (2) are formed when a methylene chloride solution of 1 is placed under 760 torr dihydrogen. Conductivity studies indicate that methylene chloride solutions of complexes 1 and 2 are weak electrolytes and only partially ionized at concentrations above 1 mM. Complex 2 is an effective hydrogenation catalyst for ethylene and 1-hexene while acetone hydrogenation is inhibited by the formation of [IrH₂(HOCH(CH₃)₂) (CO) (dppe)] (OTf) (3). Linear dimerization and polymerization of styrene occurs via a carbocationic mechanism initiated by triflic acid elimination from 2. Treatment of an acetonitrile solution of Ir(CH₃)I₂(CO) (dppe) with silver hexafluorophosphate produces the solvent promoted carbonyl insertion product [Ir(C(O)CH₃) (NCCH₃)₃ (dppe)] [PF₆]₂ (7) which readily undergoes deinsertion in methylene chloride to form [Ir(CH₃) (CO) (NCCH₃)₂ (dppe)] [PF₆]₂ (8) and acetonitrile.     

Electrophilic abstractions on Os(H)2X(NO)L2: selective access to new unsaturated cationic Os(II) hydrides

Nitrosylation of Os(H)₃ClL₂ (L = P¹Pr₃) affords the known Os(H)₂Cl(NO)L₂ (2). Soft electrophiles (Ag⁻, Na⁻) react with complex 2 by chloride abstraction to ultimately yield truly 16-electron dihydride Os(H)₂(NO)(P¹Pr₃)₂⁻ (4a), characterized by variable-temperature NMR. Complex 4a reversibly binds H₂, forming Os(H)₂(H₂)(NO)(P¹Pr₃)⁻ with an unusually high barrier for intramolecular hydride exchange. Under kinetic conditions, protonation of 2 with strong acids follows the selectivity for chloride abstraction. Thermodynamically, protonation at the hydride is preferred, quantitatively producing cationic OsHCl(NO)L₂⁺, isolated and characterized by X-ray diffraction as the BAr₄^F− salt (7) (Ar^F=3,5−(CF₃)₂C₆H₃). Structures of isoelectronic OsHCl(NO)(PH₃)₂ and OsHCl(CO)(PH₃)₂ were optimized with ab initio DFT (Becke3LYP) methods and compared to show the greater unsaturation of the metal in the cationic species. Both complexes, 4a and 7, are highly electrophilic and reversibly coordinate dichloromethane in solution. The observed reactivity patterns of the synthesized unsaturated hydrides are rationalized in terms of the determining influence of the ‘push-pull’ π-stabilization of the metal center.     

The hydrogenation and hydroformylation of alkenes as catalyzed by polymer-anchored rhodium trichloride under water gas shift reaction conditions

The ‘heterogenized’ water gas shift catalyst Rh/P4VP, prepared from the reaction of RhCl₃ with poly(4-vinylpyridine), is also active for hydrogenation and hydroformylation of 1-hexene and cyclohexene in aqueous ethoxyethanol under mild shift reaction conditions (typically 0.9 atm. P_CO at 100°C). The catalytic activities for these systems were studied as functions of several experimental variables. Hydroformylation rates increased with the P_CO but exhibited saturation behavior in the 1.5 atm. range. Rates for cyclohexane and hexane production were inhibited by CO at higher pressures. Cyclohexene hydroformylation and hydrogenation turnover frequencies were independent of the polymer-loading (50–150 μM RhCl₃/1.0 g P4VP) indicating that the active species are of the same nuclearity as the principal species present. The temperature dependence did not follow simple Arrhenius behavior, but appeared segmented. These data are discussed in terms of possible mechanisms.     

Metal carbonyls of telluroether formed by the oxygen atom transfer reaction to M(CO)6 (M = Mo, W) in the presence of (p-CH3OC6H4)2TeO and relative kinetic investigation

A new synthetic process is reported for the preparation of two substituted metal carbonyls, (p-CH₃OC₆H₄)₂TeM(CO)₅ (M = Mo, W). In the presence of (p-CH₃OC₆H₄)₂TeO as O atom transfer reagent in tetrahydrofuran solvent, a CO ligand is replaced by telluroether when M(CO)₆ (M = Mo, W) is reacted with (p-CH₃OC₆H₄)₂TeO under very mild experimental conditions (r.t.). The products were characterized by elemental analysis, mass, IR and ¹H NMR spectroscopies. The spectra suggest that the coordination geometry is distorted from a regular octahedral structure due to an asymmetrical bulky telluroether ligand on the metal atom. Kinetics of these reactions of M(CO)₆ with (p-CH₃OC₆H₄)₂TeO show the reactions are first order in the concentration of M(CO)₆ and of Te oxide. The rates of reaction decrease in the order W(CO)₆>Mo(CO)₆>Cr(CO)₆, and the results obtained are discussed in term of a presumed mechanism.     

Water soluble platinum(II) and palladium(II) complexes of alkyl sulfonated phosphines

The reactions of the alkylsulfonated phosphines LM=Ph₂P(CH₂)_nSO₃Na/K (n=2, 3, 4) with K₂PtCl₄ and K₂PdCl₄ have been studied in homogeneous aqueous solution as a function of pH. In homogeneous acidic solution the protonated phosphines react to give cis- and trans-PtCl₂(LH)₂. The biphasic reaction between 1,5-cyclooctadiene platinum(II) chloride in dichloromethane and acidified aqueous LNa/K gives a higher proportion of the cis isomer. In neutral solution the initial reaction to give [PtCl(LNa/K)₃]⁺Cl⁻ is followed by slow formation of cis-PtCl₂(LNa/K)₂. K₂PdCl₄ reacts more rapidly to give PdCl₂(LNa/K)₂. In homogeneous alkaline solution rapid oxidation of the phosphine occurs with only small amounts of platinum complex being observable. The biphasic reaction yields phosphine oxide in the aqueous layer and a small amount of the chelate complexes PtL₂ in the organic. Representative complexes have been isolated and characterised and the mechanisms for the reactions discussed. The electrospray mass spectra of solutions of the isolated complexes have been recorded in both positive and negative ionisation modes. The positive ionisation spectra are complicated, but platinum and palladium containing ions derived from loss of chloride, H⁺ and HCl are observed in the negative ionisation spectra.     

Elimination of benzene from a benzyloxy ligand to form a carbonyl group on a tungsten-phosphine center

WH₃(OCH₂C₆H₅) (PMe₃)₄ (1) is formed upon reaction of WH₂(PMe₃)₅ with benzyl alcohol for 12 days at ambient temperatures. Thermolysis of 1 at 80°C in toluene solution gives the carbonyl complex, WH₂(CO)(PMe₃)₄ (2) and benzene. The conversion is slower in the presence of H₂. Reaction of 1 with D₂ leads to H/D exchange in the hydride ligands and in the benzylic and ortho-phenyl positions of the benzyloxide. A mechanism for the thermolysis of 1, based on an H₂ elimination, sequential C-H activations, and CO deinsertion from an acyl ligand, is proposed. Thermolysis of 1 is much faster in the presence of free benzyl alcohol and 2 is not formed. The products under these conditions are toluene, bibenzyl, WH₄(PMe₃)₄, PMe₃ and unidentified material, consistent with the intermediacy of benzyl radicals.     

Structural studies on products of reduction of a nitro-Ni1C3N2-metallocene

The reduction of 12-nitro-(1,1,2,8,9,9-hexamethyl-3,7,10-14-tetraaza-4,6-oxa-5-hydra-tetradeca-2,7,10-12-tetrene)nickel(II) (Nioyl-NO₂), with Zn(s) and NaOH or HCl solution or utilizing Pd-H₂ under most conditions produces an intensely purplee complex ion ε_(max) at 552 nm which is not the expected amine. This product was found to be a conjugated dimer ion with two Nioyls multiply bonded to a single nitrogen atom. It was shown that the initial reduction produces the amine or amine hydrochloride which oxidizes rapidly in the presence of traces of O₂ under low acidity conditions to the dimer. Under high acidity conditions the amine salt is isolated. The X-ray crystal structures of three complexes are described: [(Nioyl)₂NH](ClO₄)₂·2.5CCl₄, [(Nioyl-NH₃)₂H]ZnCl₄Cl·3H₂O, [Nioyl-NH₃]H_0.5(ClO₄)_1.5·2CH₃CN·2H₂O and structural differences are discussed. The 2e⁻ reduction of [(Nioyl)₂N]⁺ with dithionite ion reversibly gives the yellow [(Nioyl)₂NH]⁺ which is extremely sensitive to air oxidation. A postulated reaction sequence is presented and discussed to explain the formation of the highly stable conjugated dimeric purple product.     

Fluoro-hydrido-oxo and other fluoro-oxo complexes of rhenium (V) containing a triphosphine ligand

The fluoro-hydrido-oxo complex [Re(F)(H)(O)Cyttp]⁺ (3, Cyttp = PhP(CH₂CH₂CH₂PCy₂)₂) was prepared in high yield from [Re(H₂)H₄Cyttp]SbF₆ (1(SbF₆), NaSbF₆ and acetone in toluene at reflux. Reaction chemistry of 3 has been studied and, where appropriate, compared with that of the related dihydrido-oxo complex [ReH₂(O)Cyttp]⁺ (2). Unlike 2, which readily reacts with both CO and SO₂, 3 was found to be inert to these reagents under comparable conditions. However, 3(SbF₆) reacts with NaSbF₆ at elevated temperature to afford the difluoro-oxo complex [ReF₂(O)Cyttp]⁺ (4). 4 undergoes fluoride substitution by Cl⁻ or Br⁻ to yield [Re(X)(F)(O)Cyttp]⁺ (X = Cl (5, Br (6)). 5 can also be obtained by treatment of 6(BPh₄) with LiCl. All of these complexes contain mer-Cyttp, and 3–6 contain trans fluoride and oxide ligands as inferred from spectroscopic data.     

Synthesis and characterization of polypyridineruthenium(II) complexes containing a linear ambidentate ligand, NCO or NCS, and reaction of isocyanato complexes under acidic conditions

Isocyanato and isothiocyanatopolypyridineruthenium complexes, [Ru(NCX)Y(bpy)(py)₂]ⁿ⁺ (bpy=2,2′-bipyridine, PY=pyridine; X=O, Y=NO₂ for n=0, and Y=py for n=1; X=S, Y=NO₂ for n=0, Y=NO for n=2, and Y=py for n=1), were synthesized by the reaction of polypyridineruthenium complexes with potassium cyanate or sodium thiocyanate salt. Isocyanatoruthenium(II) complexes, [Ru(NCO)(NO₂)(bpy)(py)₂] and [Ru(NCO)(bpy)(py)₃]⁺, react under acidic conditions to form the corresponding ammineruthenium complexes, [Ru(NO)(NH₃)(bpy)(py)₂]³⁺. The molecular structures of [Ru(NCO)(bpy)(py)₃]ClO₄, [Ru(NCS)(NO)(bpy)(py)₂](PF₆)₂ and [Ru(NO)(NH₃)(bpy)(py)₂](PF₆)₃ were determined by X-ray crystallography.     

Steric control in the formation of Co2(CO)6-alkyne complexes from Group 14 tetraalkynes and their reactions with acid

A series of tetrakis(trimethylsilylethyne) derivatives of Group 14 metals (2–4) was prepared. Co₂(CO)₆ complexes 5–10 were synthesised by the reaction of 2–4 with Co₂(CO)₈. From the silyl and germyl based compounds 2 and 3, either one or two alkynes could be complexed with Co₂(CO)₆. In contrast, the tin derived compound 4 could accommodate up to four Co₂(CO)₆ complexes. The longest wavelength UV-Vis absorbances of the silicon and germanium-based complexes were consistent with multiple, non-conjugated Co₂(CO)₆ chromophores. The tetrakis Co₂(CO)₆ complex 10, however, absorbs at a much longer wavelength suggesting conjugation of Co₂(CO)₆ complexes through the tin. The reactivity towards protonolysis of the uncomplexed alkynes 2–4 is a consequence of the hyperconjugative stabilisation of the intermediate β-vinyl cation (the β-effect): Sn(CCSiMe₃)₃>SnOTf(CCSiMe₃)₂>SiMe₃>Ge(CCSiMe₃)₃. The reactivity of the Co₂(CO)₆ complexes, however, was quite different from the reactions of 2–4 and from analogous all-carbon systems. Treatment of 5–10 with strong acid led neither to protiodemetallation of the complexed or non-complexed alkynes but to decomplexation of the cobalt. Similarly, ligand metathesis reactions between 10 and Ph₂SiCl₂ were not observed. The normal reactivity of silylalkynes towards electrophiles, which was expected to be enhanced by the presence of the cobalt complex, was diminished by the particular steric environment of the molecules under examination (5–10). As a result, the favoured reaction under these conditions was decomplexation of the cobalt.     

Polynuclear chromium(III) carboxlylates: Part 2. Chromium(III) acetate — what's in it?

Chromium(III) acetate has been widely used in industry for decades. The commercial material is an ill-defined substance, which represents a large number of compounds having different compositions, physical properties and appearances. Several samples of Cr(III) acetate, from various commercial sources were examined by ion-exchange chromatography. All the samples were found to contain several species such as [Cr₃O(O₂CCH₃)₆(H₂O)₃]⁺ and other positively charged purple complexes. They also contain various amounts of the neutral violet complex [Cr₈(OH)₈(O₂CCH₃)₁₆] (1) which crystallizes upon slow evaporation of its aqueous solution. 1 is a cyclic octanuclear complex with hydroxo and acetate ligands bridging the adjacent Cr(III) ions. The structure of a well-defined Cr(III) acetate, namely, [Cr(H₂O)₆](O₂CCH₃)₃ (2) has been determined crystallographically and its decomposition products were examined by ion-exchange chromatography. Compound 2 decomposes under ambient conditions, releasing acetic acid and water producing neutral and charged polynuclear Cr(III) complexes.     

Chemistry of vinylidene complexes XI. Synthesis of trinuclear MnFePt complexes by means of consecutive assembling out of mono- and dimetal vinylidene precursors

The dimetal μ-vinylidene complexes Cp(CO)₂MnPt(μ-C = CHPh)L₂ (L = tert.-phosphine or -phosphite), which have been obtained by coupling of the mononuclear complex Cp(CO)₂Mn=C=CHPh and unsaturated PtL₂ unit, add smoothly the Fe(CO)₄ moiety to produce trimetal MnFePt compounds. The μ₃-vinylidene cluster CpMnFePt(μ₃-C=CHPh)(CO)₆(PPh₃) was prepared in quantitative yields from the reactions of Cp(CO)₂MnPt(μ-C=CHPh)(PPh₃)L (L = PPh₃ or CO) with Fe₂(CO)₉ in benzene at 20 °C. The phosphite-substituted complexes Cp(CO)₂Mnpt(μ-C=CHPh)L₂ (L = P(OEt)₃ or P(OPrⁱ)₃) react under analogous conditions with Fe₂(CO)₉ to give mixtures (2:3) of the penta- and hexacarbonyl clusters, CpMnFePt(μ₃-C = CHPh)(CO)₅L₂ and CpMnFePt(μ₃-C = CHPh)(CO)₆L, respectively. The similar reaction of the dimetal complex Cp(CO)₂MnPt(μ-C = CHPh)(dppm), in which the Pt atom is chelated by dppm = Ph₂PCH₂PPhPin2 ligand, gives only a 15% yield of the analogous trimetal μ₃-vinylidene hexacarbonyl product CpMnFePt(μ₃-C = CHPh)(CO)(dppm), but the major product (40%) is the tetranuclear μ₄-vinylidene cluster (dppm)PtFe₃(μ₄-C = CHPh)(CO)₉. The IR and ¹H, ¹³C and ³¹P NMR data for the new complexes are reported and discussed.     

Synthesis and reactivity of diphosphino Pt(II) silanolate complexes as molecular models of the interaction of platinum particles with silica

A series of di- and monosubstituted cis-platinum(II) silanolate complexes, Pt(OSiR₃)₂(dppe) (R=Et, 1; R=Me, 2) and Pt(OSiR₃)Cl(dppe) (R=Et, 3; R=ⁱPr, 4) where dppe is 1,2-bis(diphenylphosphino)ethane, have been isolated and characterised spectroscopically. Complex 1 does not react with CO and H₂ under anhydrous conditions, but the complexes Pt{C(O)OCH₃)}₂(dppe) (6) and Pt(CO₃)(dppe) (7) have been isolated bubbling CO in methanol and CO₂ in moist benzene solutions of 1, respectively. The behaviour of 1 towards water or methanol is discussed on the basis of ¹H, and ³¹P{¹H} NMR spectroscopic data. The new complex Pt{S₂C(OSiEt₃)₂}(dppe) (8) has been isolated by reaction of 1 with CS₂ in benzene solution. This reactivity would suggest a high sensitivity towards water, but not towards H₂ or CO, of the bonding of slightly oxidised platinum particles with silanol groups of silica surface.     

The migratory insertion of carbon monoxide in pentamethylcyclopentadienyliridium (III) complexes. Structural effects on reactivity and mechanism for rhodium and iridium systems

The reactions of complex (C₅Me₅)Ir(Cl) (CO) (Me) (1a) with cyclohexylisocyanide and phosphines (L=CyNC, PHPh₂, PMePh₂, PMe₂Ph) give the products of alkyl migratory insertion (C₅Me₅Ir(Cl) (COMe) (L), in toluence or tetrahydrofuran at 323 K or higher temperature. The phenyl analogue (C₅Me₅)Ir(Cl)(CO)(Ph) or the iodide complexes (C₅Me₅)Ir(I) (CO) (R) (R=Me, Ph_are not reactive under the same conditions. The reaction of (C₅Me₅)Ir(Cl)(CO)(Me) with PMePh₂ and PMe₂Ph in acetonitrile yields the chloride substitution product [(C₅Me₅)Ir(CO)(L)(Me)]⁺Cl⁻. Kinetic measurements for the reactions of (C₅Me₅)Ir(Cl)(CO)(Me) in toluene are first order in the iridium complex and exhibit a saturation dependence on the incoming donors L. Analysis of the data suggests a two-step process involving (i) rapid formation of a molecular complex [(C₅Me₅)Ir(Cl)(CO)(Me), (L)], in which the structure of 1a is unperturbed within the limits of spectroscopic analysis, and (ii) rate determining methyl migration. The reaction parameters are K for the pre-equilibrium step (K = 1.5 (CyNC), 7.3 (PHPh₂), 7.1 (PMePh₂) dm³ mol⁻¹ at 323 K) and k₂ for the slow carbon---carbon bond formation (k₂ (10⁵) = 6.9 (CyNC), 1.2 (PHPh₂), 1.0 (PMePh₂) s⁻¹ at 323 K). The activation parameters for the methyl migration step in the reaction with PMePh₂ obtained between 308 and 338 K, are ΔH^≠ = 106±16 kJ mol⁻¹ and ΔS^≠ = − 14±5 J K⁻¹ mol⁻¹. The reaction of 1a with PMePh₂ proceeds at similar rates in tetrahydrofuran (K = 3.7 dm³ mol⁻¹, k₂ (10⁵) = 1.2 s⁻¹, 323 K). The crystal structure of (C₅Me₅)Ir(Cl)(COMe) (PMe₂Ph) has been determined by X-ray diffraction. C₂₀H₂₉ClOPIr: M_r = 544.1, monoclinic, P2₁/n, A = 8.084 (2), B = 9.030(2), C = 28.715 (3) Å, β = 91.41 (3)°, Z = 4, D_c = 1.71 g cm⁻³, V = 2095.5 ų, room temperatyre, Mo K, γ = 0.71069, μ = 65.55 cm⁻¹, F(000) = 1044, R = 0.037 for 2453 independent observed reflections. The complex shows a deformed tetrahedral coordination assuming the η⁵-C₅Me₅ molecular fragment as a single coordination site. The iridium-chlorine bond is staggered with respect to two adjacent C(ring)-methyl bonds, while the Ir---P and the Ir---COMe bonds are eclipsed with respect to C(ring)-methyl bonds.     

The synthesis of substituted bis[(diarylphosphinomethyl)cyclopentadienyl]zirconocene dichloride complexes for the preparation of heterodimetallic complexes containing early/late transition metal combinations

Fulvenes (1a–e) derived from condensation of cyclopentadiene with acetone or a variety of aldehydes were treated with LiPAr₂ (Ar = phenyl, p-tolyl) to yield the respective substituted (diarylphosphinomethyl)cyclopentadienides (2, 3). Subsequent reaction with ZrCl₄(THF)₂ gave the respective bis[(diarylphosphinomethy])cyclopentadienyl]zirconium dichlorides ( Ar = phenyl (4), p-tolyl (5)). The complex rac-[C₅H₄-CH(CH₃)-PPh₂]₂ZrCl₂ (rac-4b) was characterized by X-ray diffraction. The reaction of complexes 4a and 5a [(Cp-CMe₂-PAr₂)₂ZrCl₂] with PdCl₂(NCPh)₂ or PtCl₂(NCPh)₂ leads to the formation of the trans-(metallocene-chelate-phosphane)metal complexes 6–9 (e.g. trans-Cl₂Pd(Ph₂P-CMe₂-Cp)₂ZrCl₂]. Chloride abstraction from the reaction product of [Cp-CH(CMe₃)PPh₂]₂ZrCl₂ with PdCl₂(NCPh)₂ eventually gave the cationic complex [meso,trans-(Cp-CH(CMe₃)PPh₂)₂(Cl)Zr(μ-Cl)Pd(Cl)]⁺ (10) that was also characterized by X-ray diffraction. It features a dimetallabicyclic framework with two Cp-CHR-PPh₂ ligands and a chloride bridging between the early and the late transition metal center.     

On the mechanism of silylformylation catalyzed by Rh-Co mixed metal complexes

Possible mechanisms for the silylformylation of 1-alkynes catalyzed by Rh₂Co₂(CO)₁₂ are investigated. Novel Rh-Co mixed metal complexes, (PhMe₂Si)₂Rh(CO)nCo(CO)₄ (n = 2 or 3) (3) and RhCo(HC≡CBuⁿ)(CO)₅ (5), are found to play important roles in this catalysis. The reaction of 3 with 1-hexyne and HSiMe₂Ph at ambient temperature and pressure of CO gives n-BuC(CHO)=CHSiMe₂Ph (1a, Z/E = 95/5), (PhMe₂Si)₂Rh(CO)₃Co(CO)₄ (3-B) and an Rh-Co mixed metal butterfly complex, h₂Co₂(HC≡CBuⁿ)(CO)₁₀ (4). The reaction of 5 with 1-hexyne and HSiMe₂Ph under the same ambient conditions affords 1a (100% Z) very cleanly as the sole reaction product. The crossover experiments u sing RhCo(DC≡CBuⁿ)(CO)₅(5-d), 1-hexyne-1d and DSiMe₂Ph strongly support the mixed metal bimetallic catalysis and involvement of bis(alkyne)-Rh-Co species. The most plausible catalytic cycle of silylformylation which can accommodate all the observed results is proposed.     

Synthesis and properties of the dichloro [tetramethyl (trifluoromethyl)cyclopentadienyl]ruthenium dimer: X-ray structure of [M2(η-C5Me4CF3)2Cl2(μ-Cl)2] (M=Ru, Rh)

The reaction of RuCl₃(H₂O), with C₅Me₄CF₃J in refluxing EtOH gives [Ru₂(η⁵-C₅Me₁CF₂)₂ (μ-Cl₂] (20 in 44% yield. Dimer 2 antiferromagnetic (−2J=200 cm¹). The crystal structures of 2 (rhombohedral system, R3 space group, Z=9, R=0.0589) and [Rh₂(η⁵-C₅Me₄CF₃(₂Cl₂(μ-Cl)₂] (3) (rhombohedral system. space group, Z = 9, R = 0.0641) were solved; both complexes have dimeric structures with a trans arrangement of the η⁵-C₅Me₄CF₄ rings. Comparison of the geometry of 2 and 3 with those of the corresponding η⁵-C₅Me₅ complexes shows that lowering the ring symmetry causes significant distortion of the M₂(μ-Cl)₂ moiety. The analysis of the MCl₃ fragment conformations in 2 and 3 and in the η⁵-C₅ME₅ analogues shows that they are correlated with the M---M distances. The Cl atoms are displaced by Br on reaction of 2 with KBr in MeOH to give the diamagnetic dimer [Ru₂(η⁵-C₅Me₄CF₃)₂Br₂ (μ-Br₂] (4). Complex 2 reacts with O₂ in CH₂Cl₂ solution at ambient temperature to form a mixture of isomeric η⁶-fulvene dimers [Ru₂(η⁶-C₅Me₃CF₃ = CH₂)₂Cl₂(μ-Cl)₂] (5). Reactions of 5 with CO and allyl chloride give Ru(η⁵-C₅Me₃CF₃CH₂Cl)(CO)₂Cl (6) and Ru(η⁵-C₅Me₃CF₃CF₃CH₂Cl)(η³-C₃H₅)Cl₂ (7) respectively.     

Palladium complexes with PCP ligands.: Preparation and structural studies of two forms of [(PCP)Pd(OH2)]BF4

Abstraction of chloride from the Pd complex {[η³-2,6-(^tBu₂PCH₂)₂C₆H₃)]PdCl with AgBF₄ in THF gives {[η³-2,6-(^tBu₂PCH₂)₂C₆H₃)]Pd(THF)}⁺BF₄ ⁻. Attemped crystallization of this THF complex produced the aqua complex {[η³-2,6-(^tBu₂PCH₂)₂C₆H₃)]Pd(OH₂)}⁺BF₄ ⁻. Crystal structures of two crystalline forms of this compound are reported. In {[η³-2,6-(^tBu₂PCH₂)₂C₆H₃)]Pd(OH₂)}⁺BF₄ ⁻·THF, one hydrogen of the water is hydrogen bonded to the oxygen of the THF, and the other hydrogen is hydrogen bonded to an F of the BF₄ ⁻ anion. Another crystalline form has no THF, but has both of the hydrogens of water hydrogen bonded to different BF₄ ⁻ anions, such that two different BF₄ ⁻ anions bridge two {[η³-2,6-(^tBu₂PCH₂)₂C₆H₃)]Pd(OH₂)}⁺ cations. A crystal structure is also reported for the palladium chloride complex [η³-2,6-(^tBu₂PCH₂)₂C₆H₃)]PdCl.     

Synthesis and reactivity of coordinatively unsaturated osmium and ruthenium stannyl complexes

Treatment of MHCl(CO)(PPh₃)₃ (M=Ru, Os) with (CH₂=CH)SnR₃ is a good general route to the coordinatively unsaturated osmium and ruthenium stannyl complexes M(SnR₃)Cl(CO)(PPh₃)₂ (1: M=Ru, R=Me; 2: M=Ru, R = n-butyl; 3: M=Ru, R = p-tolyl; 4: M=Os, R=Me). These coordinatively unsaturated complexes readily add CO and CN-p-tolyl to form the coordinatively saturated compounds M(SnR₃)Cl(CO)L(PPh₃)₂ (5: M=Ru, R=Me, L=CO; 6: M=;Ru, R = n-butyl, L=CO; 7: M=Ru, R = p-tolyl, L=CO; 8: M=Os, R=Me, L=CO; 9: M=Ru, R=Me, L=CN-p-tolyl; 10: M=Ru, R = n-butyl, L=CN-p-tolyl; 11: M=Os, R=Me, L=CN-p-tolyl). In addition, the chloride ligand in Ru(SnR₃)Cl(CO)(PPh₃)₂ proves to be labile and treatment with the potentially bidentate anionic ligands, dimethyldithiocarbamate or diethyldithiocarbamate, affords the coordinatively saturated compounds Ru(SnR₃)(η²-S₂CNR′₂)(CO)(PPh₃)₂ (12: R=Me, R′ = Me; 13: R=Me, R′ = Et; 14: R = n-butyl, R′ = Me; 15: R = p-tolyl, R′ = Me; 16: R = p-tolyl, R′ = Et). Chloride is also displaced by carboxylates forming the six-coordinate compounds Ru(SnR₃)(η²-O₂CR′)(CO)(PPh₃)₂ (17: R=Me, R′ = H; 18: R=Me, R′ = Me; 19: R=Me, R′ = Ph; 20: R = n-butyl, R′ = Me; 21: R = p-tolyl, R′ = Me). IR and ¹H NMR spectral data for all the new compounds and ³¹P and ¹¹⁹Sn NMR spectral data for selected compounds are reported.     

Second sphere coordination behavior of aquo and amine ligands bound to a η-benzeneruthenium(II) cation

The bis(oxazoline) ligand, 2,2-bis[4(R)-phenyl-1,3-oxazolon-2-yl]propane (bpop), was introduced to the η⁶-benzenemthenium(II) moiety on treatment with [Ru(η⁶-C₆H₆)Cl₂]₂ to give [Ru(η⁶-C₆H₆)(bpop)Cl]⁺. Aquo and amine complexes [Ru(η⁶-C₆H₆)(bpop)(L)]²⁺ (L = H₂O (1), NH₂R; R = H (2) , Me (3) , and n-Bu (4) ) were prepared by treating the chloride complex with AgBF₄ in the presence of L. X-ray structure determinations of 1 and 3 were carried out. Both complexes possessed a three-leg piano stool structure with the N or O donors located at the three comers of a pseudo octahedron. The aquo complex 1 exhibited a dynamic NMR feature in which two magnetically nonequivalent oxazoline parts observed at lower temperatures were interchanged with each other at higher temperatures. This observation was ascribed to the formation of a C₂-symmetric 16-electron intermediate via Ru-OH₂ cleavage, which is slower in acetone than in dichloromethane owing to more effective solvation by acetone around hydrogens of the coordinated water molecule. The two diastereotopic N-hydrogens of 4 underwent deuterium exchange with CD₃OD with greatly different rates from each other owing to different energy of NHO (D) (CD₃) interaction. Carboxylate and sulfonate ions (A⁻) formed second sphere complexes with 4 by means of NHA⁻ hydrogen bonding, as evidenced by continuous shift of NH₂ resonances with increasing amounts of the anions added.