Carbomolybdate clusters formed by carbonyl insertion into molybdenum-oxygen bonds. Structural investigation of the [RMo4O15X] core (R = ---C9H4O, X = OCH3; R = ---C14H10, X = ---C7H5O2; R = C14H8, X = ---OH)

[C₄H₉)₄N]₂[Mo₂O₇] reacts with a variety of organic species containing α-diketone groups to give tetranuclear complexes of general composition [RMo₄O₁₅X]³⁻. The complexes [(C₄H₉)₄N]₃[(C₉H₄O)Mo₄O₁₅(OCH₃)] (I), [(C₄H₉)₄N]₃[(C₁₄H₁₀)Mo₄O₁₅(C₆H₅CO₂)] (11) and [(C₄H₉)₄N]₃[(C₁₄H₈)Mo₄O₁₅(OH)] (III) were synthesized from the reactions of dimolybdate with ninhydrin, benzil and phenanthraquinone, respectively. Complex II may also be prepared from dimolybdate and benzoin in acetonitrile-methanol solution, from which it co-crystallizes with the binuclear species [(C₄H₉)₄N]₂[Mo₂O₅(C₆H₅C(O)C(O)C₆H₅)₂] · CH₃CN · CH₃OH (IV). Complexes I–III exhibit the tetranuclear core, previously described for the α-glyoxal derivatives [(C₄H₉)₄N]₃[(HCCH)Mo₄O₁₅X], where X = F⁻ or HCO₂⁻. The ligands may be formally described as diketals, formed by insertion of ligand carbonyl subunits into molybdenum-oxygen bonds. The structures I–III differ most dramatically in the identity and coordination mode of the anionic ligand X⁻ which occupies a position opposite the diketal moiety relative to the [Mo₄O₁₁]²⁺ central cage. Thus, I exhibits a doubly bridging methoxy group in this position, while II possesses a benzoate ligand with an unusual μ₃-O,O′coordination mode. Complex III presents a hydroxy-group unsymmetrically bonded to three of the molybdenum centres. The stereochemical consequences of the various coordination modes are discussed. Crystal data: Compound I, monoclinic space group Pc, a = 24.888(2), b = 12.897(3), c = 24.900(3) Å, β = 101.94(2)°, D_calc = 1.28 g cm⁻¹ for Z = 4. Structure solution and refinement based on 8695 reflections with F_o 6σ(F_o) (Mo-K_α, λ = 0.71073 Å) converged at a conventional discrepancy factor of 0.060. Compound II, orthorhombic space group Pbca, a = 20.426(6), b = 26.916(6), c = 32.147(7) Å, V = 17673.2(20) ų, D_calc = 1.33 g cm⁻³ for Z = 8; 5224 reflections, R = 0.076. Compound III, tetragonal space group I4₁/a, a = b = 48.129(6), c = 13.057(2) Å, V = 30246.2(12) ų, D_calc = 1.35 g cm⁻³ for Z = 16; 5554 reflections, R = 0.053. Compound IV, orthorhombic space group Pnca, a = 16.097(4), b = 16.755(4), c = 25.986(7) Å, V = 7008.1(13) ų, Z = 4, D_calc = 1.18 g cm⁻³ ; 2944 reflections, R = 0.061.     

Synthesis and reaction chemistry of 4-nitrile-substituted NCN-pincer palladium(II) and platinum(II) complexes (NCN = [NC-4-C6H2(CH2NMe2)2-2,6])

Nitrile-functionalized NCN-pincer complexes of type [MBr(NC-4-C₆H₂(CH₂NMe₂)₂-2,6)] (6a, M = Pd; 6b, M = Pt) (NCN = [C₆H₂(CH₂NMe₂)₂-2,6]⁻) are accessible by the reaction of Br-1-NC-4-C₆H₂(CH₂NMe₂)₂-2,6 (2b) with [Pd₂(dba)₃ · CHCl₃] (5a) (dba = dibenzylidene acetone) and [Pt(tol-4)₂(SEt₂)]₂ (5b) (tol = tolyl), respectively. Complex 6b could successfully be converted to the linear coordination polymer {[Pt(NC-4-C₆H₂(CH₂NMe₂)₂-2,6)](ClO₄)}_n (8) upon its reaction with the organometallic heterobimetallic π-tweezer compound {[Ti](μ-σ,π-CCSiMe₃)₂}AgOClO₃ (7) ([Ti] = (η⁵-C₅H₄SiMe₃)₂Ti).The structures of 6a (M = Pd) and 6b (M = Pt) in the solid state are reported. In both complexes the d⁸-configurated transition metal ions palladium(II) and platinum(II) possess a somewhat distorted square-planar coordination sphere. Coordination number 4 at the group-10 metal atoms M is reached by the coordination of two ortho-substituents Me₂NCH₂, the NCN ipso-carbon atom and the bromide ligand. The NC group is para-positioned with respect to M.     

Reactions of the cycloheptatrienyl complexes [MX(CO)2(η-C7H7)] (M=Mo, X=Br; M=W, X=I) with CNBu: X-ray crystal structure of [WI(CO)2(CNBu)2(η-C7H7)]

Reaction of [MX(CO)₂(η⁷-C₇H₇)] (M=Mo, X=Br; M=W, X=I) with two equivalents of CNBu^t in toluene affords the trihapto-bonded cycloheptatrienyl complexes [MX(CO)₂(CNBu^t)₂(η³-C₇H₇)] (1, M=Mo, X=Br; 2, M=W, X=I). The X-ray crystal structure of 2 reveals a pseudo-octahedral molecular geometry with an asymmetric ligand arrangement at tungsten in which one CNBu^t is located trans to the η³-C₇H₇ ring. Treatment of 2 with tetracyanoethene results in 1,4-cycloaddition at the η³-C₇H₇ ring to give [WI(CO)₂(CNBu^t)₂{η³-C₉H₇(CN)₄}], 3. The principal reaction type of the molybdenum complex 1 is loss of carbonyl and bromide ligands to afford substituted products [MoBr(CNBu^t)₂(η⁷-C₇H₇)] 4 or [Mo(CO)(CNBu^t)₂(η⁷-C₇H₇)]Br. Reaction of [MoBr(CO)₂(η⁷-C₇H₇)] with one equivalent of CNBu^t in toluene at 60°C affords [MoBr(CO)(CNBu^t)(η⁷-C₇H₇)], 5, which is a precursor to [Mo(CO)(CNBu^t)(NCMe)(η⁷-C₇H₇)][BF₄], 6, by reaction with Ag[BF₄] in acetonitrile. In contrast with the parent dicarbonyl systems [MoX(CO)₂(η⁷-C₇H₇)], complexes of the Mo(CO)(CNBu^t)(η⁷-C₇H₇) auxiliary, 5 and 6, do not afford observable η³-C₇H₇ products by ligand addition at the molybdenum centre.     

Cathodic behaviour of [*η-C3H5)Pd(Ph2P-C2H4-PPh2)] in acetonitrile solution: an electrochemical process involving very fast consecutive chemical reactions

The cathodic reduction of [(η³-C₃H₅)Pd(Ph₂P-C₂H₄-PPh₂)]⁺, A, in acetonitrile solution affords Pd(Ph₂P-C₂H₄-PPh₂)₂, B, and Pd(η³-C₃H₅)₂, C. Its cyclic voltammetric behaviour is studied as a function of scan rate and concentration of A. These results and relevant coulometric experiments indicate a primary reversible charge transfer reaction followed by a fast second order process producing P₁ and P₂. This picture is complicated by a subsequent reaction of B with A leading to a dimeric electroactive species which is reduced at a slightly more negative potential value than A. The rate constants of individual chemical reactions were evaluated by digital simulation and best fit with experimental results.     

Reactions of tungsten and molybdenum propargyl complexes with Co2(CO)8, Co4(CO)12, and Cp2Mo2(CO)4. A crossover study of formation of (CO)3 Cp(CO)2

The nature of the protonation reaction of (

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o(CO)₃ (M = Mo, W; R = Me, Ph, p-MeC₆H₄) (2) (obtained from (CO)₃CpMCH₂CCR (1) and Co₂(CO)₈) to give (CO)₃ Cp(CO)₂ (3) was further investigated by a crossover experiment. Thus, reaction of an equimolar mixture of 2b (M = W, Cp = η⁵-C₅H₅, R = Ph) and 2e (M = W, Cp = η⁵-C₅H₄Me; R = p-MeC₆H₄) with CF₃COOH affords only 3b (same M, Cp, and R as 2b) and 3e (same M, Cp, and R as 2e) to show an intramolecular nature of this transformation. Reaction of (CO)₃CpWCH₂CCPh (1b) with Co₄(CO)₁₂ was also examined and found to yield 2b exclusively. Treatment of 1 with Cp₂Mo₂(CO)₄ at 0–5°C provides thermally sensitive compounds, possibly (CO)₂Cp

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oCp(CO)₂ (5), which decompose at room temperature to give Cp₂Mo₂(CO)₆ as the only isolated product.     

Synthesis and characterization of hetero-binuclear Co-Rh complexes [CpCoS2C2(B9H10)][Rh(COD)] and [CpCoSe2C2(B10H10)][Rh(COD)]

Two hetero-binuclear complexes [Cp^∗CoS₂C₂(B₉H₁₀)][Rh(COD)] (2a) and [Cp^∗CoSe₂C₂(B₁₀H₁₀)][Rh(COD)] (2b) [Cp^∗ = η⁵-pentamethylcyclopentadienyl, COD = cyclo-octa-1,5-diene (C₈H₁₂)] were synthesized by the reactions of half-sandwich complexes [Cp^∗CoE₂C₂(B₁₀H₁₀)] [E = S (1a), Se (1b)] with low valent transition metal complexes [Rh(COD)(OEt)]₂ and [Rh(COD)(OMe)]₂. Although the reaction conditions are the same, the structures of two products for dithiolato carborane and diselenolato carborane are different. The cage of the carborane in 2a was opened; However, the carborane cage in 2b was intact. Complexes 2a and 2b have been fully characterized by ¹H, ¹¹B NMR and IR spectroscopy, as well as by elemental analyses. The molecular structures of 2a and 2b have been determined by single-crystal X-ray diffraction analyses and strong metal-metal interactions between cobalt and rhodium atoms (2.6260 Å (2a) and 2.7057 Å (2b)) are existent.     

Di- and tetranulcear Ru complexes of phenylene-1,4-diaminotetra(phosphonite), p-C6H4[N{P(OC6H4OMe-o)2}2]2 and their catalytic investigation towards transfer hydrogenation reactions

The stoichiometric reaction of phenylene-1,4-diaminotetra(phosphonite), p-C₆H₄[N{P(OC₆H₄OMe-o)₂}₂]₂ (P₂NФNP₂) (1) with [RuCl₂(p-cymene)]₂ in acetonitrile produces cis,cis-[{RuCl₂(CH₃CN)₂}₂(P₂NФNP₂)] (2), whereas the similar reaction of 1 with [RuCl₂(p-cymene)]₂ in THF medium affords a tri-chloro-bridged tetrametallic complex, [{(η⁶-p-cymene)Ru₂(μ₂-Cl)₃Cl}₂(P₂NФNP₂)] (3) irrespective of the stoichiometry and reaction conditions. The formation and structure of complexes 2 and 3 are assigned through various spectroscopic and micro analysis data. The molecular structure of 2 is confirmed by single crystal X-ray diffraction study. The catalytic activities of complexes 2 and 3 have been investigated in transfer hydrogenation reactions.     

Five-coordinate pentafluorobenzothiolate osmium(IV) complexes [Os(SC6F5)4(P(C6H4X-4)3)] (X = OCH3, CH3, F, Cl or CF3): Solid and solution structural characterization

The reactions of OsO₄ with excess of HSC₆F₅ and P(C₆H₄X-4)₃ in ethanol afford the five-coordinate compounds [Os(SC₆F₅)₄(P(C₆H₄X-4)₃)] where X = OCH₃ 1a and 1b, CH₃ 2a and 2b, F 3a and 3b, Cl 4a and 4b or CF₃ 5a and 5b. Single crystal X-ray diffraction studies of 1 to 5 exhibit a common pattern with an osmium center in a trigonal-bipyramidal coordination arrangement. The axial positions are occupied by mutually trans thiolate and phosphane ligands, while the remaining three equatorial positions are occupied by three thiolate ligands. The three pentafluorophenyl rings of the equatorial ligands are directed upwards, away from the axial phosphane ligand in the arrangement “3-up” (isomers a). On the other hand, ³¹P{¹H} and ¹⁹F NMR studies at room temperature reveal the presence of two isomers in solution: The “3-up” isomer (a) with the three C₆F₅-rings of the equatorial ligands directed towards the axial thiolate ligand, and the “2-up, 1-down” isomer (b) with two C₆F₅-rings of the equatorial ligands directed towards the axial thiolate and the C₆F₅-ring of the third equatorial ligand directed towards the axial phosphane. Bidimensional ¹⁹F–¹⁹F NMR studies encompass the two sub-spectra for the isomers a (“3-up”) and b (“2-up, 1-down”). Variable temperature ¹⁹F NMR experiments showed that these isomers are fluxional. Thus, the ¹⁹F NMR sub-spectra for the “2-up, 1-down” isomers (b) at room temperature indicate that the two S-C₆F₅ ligands in the 2-up equatorial positions have restricted rotation about their C–S bonds, but this rotation becomes free as the temperature increases. Room temperature ¹⁹F NMR spectra of 3 and 5 also indicate restricted rotation around the Os–P bonds in the “2-up, 1-down” isomers (b). In addition, as the temperature increases, the ¹⁹F NMR spectra tend to be consistent with an increased rate of the isomeric exchange. Variable temperature ³¹P{¹H} NMR studies also confirm that, as the temperature is increased, the a and b isomeric exchange becomes fast on the NMR time scale.     

(C6H16N2)Zn3(HPO3)4H2O: a new layered zinc phosphite templated by diprotonated trans-1,4-diaminocyclohexane

Employing trans-1,4-diaminocyclohexane (trans-1,4-DACH) as a template, a new two-dimensional layered zinc phosphite (C₆H₁₆N₂)Zn₃(HPO₃)₄H₂O (1) has been prepared hydrothermally. Single-crystal X-ray diffraction analysis shows that it crystallizes in the monoclinic space group P2₁/n with a=10.458(2) Å, b=14.720(3) Å, c=13.079(3) Å, β=97.93(3)°, V=1994.1(7) ų, Z=4, R₁=0.0349 (I>2σ(I)) and wR₂=0.0605 (all data). The inorganic layer is built up by alternation of ZnO₄ tetrahedra and HPO₃ pseudo pyramids forming a 4.6.8-net. The sheet is featured by a series of capped six-membered rings. The diprotonated trans-1,4-DACH molecules reside in the interlayer region and interact with the inorganic network through H-bonds.     

Cycloadditionsreaktionen von Organometall-Komplexen : XV. [2 + 31- und [2 + 1]-Cycloadditionsreaktionen von Carbonylrhodium- und Carbonylcobalt-Komplexen mit Nitriloxiden und Aziden. Die Kristall- und Molekülstruktur von C5H5(PPr3) (C6H5)

The reaction of C₅H₅Rh(CO)(PⁱPr₃) (1] which is prepared from C₅H₅Rh(CO)₂ and neat P¹Pr₃, with the nitriloxides 2-RC₆H₄CNO (R = H, Cl) leads to the formation of the metallaheterocycles C₅H₅(P¹Pr₃) ) (2, 3) in 90–95% yield. Compound 1 reacts with tosylazide to give the C,N-bound isocyanate complex C₅ H₅(PⁱPr₃)Rh(η²-TosN=C=O) (6). Analogously, on treatment of C₅Me₅Co(CO)(PMe₃) with phenylazide the phenylisocyanate derivative C₅Me₅(PMe₃)Co(η²-PhN=C=O) (7) is formed. Protonation of 7 with CF₃CO ₂H affords the non-ionic carbamoylcobalt complex C₅Me₅(PMe₃)Co[C(O)NHPh](O₂CCF₃) (8). The X-ray structural analysis of 2 reveals the presence of an almost planar heterocycle in which the two Rh-C distances differ by 0.045 Å     

Structure cristalline d'un phosphochromate acide de cuivre potassium: CuK2H2(PCrO7)2

CuK₂H₂(PCrO₇)₂ is monoclinic, P2₁/c, with a unit cell: a=9.559(5)Å; b=7.196(5)Å; c=8.983(5)Å;β=93.73(5)°; Z=2; and D=2.87g/cm³.The crystal structure of this compound has been resolved by using 1938 independent reflections with a final R value of 0.03. The main feature of this compound is the existence of the mixed pyro-group CrPO₇, up to now the first to be described.     

η-Alkynyl and vinylidene transition metal complexes: 10. Reaction of the metal-acetylide [(η-C5H5)(CO)(NO)W---CC---C(CH3)3]Li with 1,2-diiodoethane as electrophile and with various nucleophiles

Treatment of the η¹-acetylide complex [(η⁵-C₅H₅)(CO)(NO)W---CC---C(CH₃)₃]Li (4) with 1,2-diiodoethane in THF at −78 °C, followed by the addition of Li---CC---R [R=C(CH₃)₃, C₆H₅, Si(CH₃)₃, 6a–6c] or n-C₄H₉Li and protonation with H₂O, afforded the corresponding oxametallacyclopentadienyl complexes (η⁵-C₅H₅)W(I)(NO)[η²-O=C(CC---R)CH=CC(CH₃)₃] (7a–7c), 8c and (η⁵-C₅H₅)W(I)(NO)[η²-O=C(n-C₄H₉)CH=CC(CH₃)₃] (9). The formation of these metallafuran derivatives is rationalized by the electrophilic attack of 1,2-diiodoethane onto the metal center of 4 to form first the neutral complex [(η⁵-C₅H₅)(I)(CO)(NO)W---CC---C(CH₃)₃] (5). Subsequent nucleophilic addition of Li---CC---R 6a–6c or n-C₄H₉Li and a reductive elimination step followed by protonation leads to the products 7a–7c and 9. One reaction intermediate could be trapped with CF₃SO₃CH₃ and characterized by a crystal structure analysis. The identity of another intermediate was established by infrared spectroscopic data. The oxametallacyclopentadienyl complex 10 forms in the presence of excess 1,2-diiodoethane through an alternative pathway and crystallizes as a clathrate containing iodine.     

The Cu(I) thiocyanate complexes with N-allylquinolinium: Synthesis and crystal structures of [C9H7NC3H5]Cu(SCN)2 and [C9H7NC3H5]Cu2(SCN)3

The crystals of [C₉H₇NC₃H₅]Cu(SCN)₂ (I) and [C₉H₇NC₃H₅]Cu₂(SCN)₃ (II) were obtained in the reaction of N-allylquinolinium bromide with CuSCN and NH₄SCN in a methanol solution. The crystals of I are triclinic: space group P , Z = 2, a = 8.619(2), b = 8.755(2), c = 10.463(3) ?, α = 77.18(3), β = 69.95(3), γ = 79.38(3)°, V = 718.1(3) ?³. The crystals of II are opthorhombic: space group P2₁2₁2₁, Z = 4, a = 5.744(2), b = 16.799(4), c = 17.980(5), V = 1735.9(9) ?³. The structure of compound I is built of infinite linear {Cu(SCN)₂⁻}_∞ anions and the N-allylquinolinium cations bonded additionally by relatively weak hydrogen contacts C-H...S. The [C₉H₇NC₃H₅]⁺ cations are located between the corrugated layers of the {Cu₂(SCN)₃⁻}_∞ anions in compound II. As in the case of the previously studied copper(I) halide complexes, the C=C bond of the allyl group in the N-allylquinolinium cation of complexes I, II does not interact with Cu(I). Original Russian Text ? A.V. Pavlyuk, V. Kinzhybalo, T. Lis, M.G. Mys’kiv, 2008, published in Koordinatsionnaya Khimiya, 2008, Vol. 34, No. 10, pp. 764–769.     

A novel cis-push–pull effect in cycloruthenated azobenzene thiocarbonyl-containing complexes: crystal and molecular structures of [RuX(CS)(η-C,N-C6H4N=NPh)(PPh3)2](X=Cl, I)

Treatment of [RuHCl(CS)(PPh₃)₃] with Hg(o-C₆H₄N=NC₆H₅)₂ affords [RuCl(CS)(η²C,N-o-C₆H₄N=NC₆H₅)(PPh₃)₂] (1) in good yield, where the cyclometallated azobenzene ligand coordinates through an ortho-C and one azo-N to give a five-membered chelate ring. Reaction of 1 with AgNO₃ followed by NaBr or NaI affords the chloride-exchanged products [RuX(CO)(η²C,N-o-C₆H₄N=NC₆H₅)(PPh₃)₂] (2, 3), whereas reaction of 1 with AgOC(O)Me or NaS₂CNEt₂·2H₂O gives the halide mono-phosphine-substituted complexes [Ru(CS)(LL)(η²C,N-o-C₆H₄NNC₆H₅)(PPh₃)] (4, 5). In the solid-state structures of 1 and 3 there are significant changes in the bond lengths for the cyclometallated azobenzene ligand are observed relative to free azobenzene. These are discussed, with the aid of spectroscopic and crystallographic data, in terms of a cis-push–pull effect.     

The structure of C2H5InBr2 · tmen,C2H5InI2 · tmen (tmen = N,N,N,′,N′-tetramethylethanediamine) and [(C6H5)4P][C2H5InI3] in solution and in the solid state

The ¹H NMR spectra of C₂H₅InBr₂ · tmen (1) C₂H₅InI₂ · tmen (2) (tmen = N,N,N′,N′-tetramethylethanediamme) and [(C₆H₅)₄P][C₂H₅InI₃] (3) show only a broad singlet for the ethyl protons at 60 MHz. Spectra run at 400 MHz resolve these into a triplet + quartet for 1 and 3. The structure of each compound has been determined by X-ray crystallography; 1 and 2 are five-coordinate species, with InC₂N₂X (X = Br, I) nuclei, while 3 consists of [(C₆H₅)₄P]⁺ cations and anions whose InCI₃ nucleus has C_3v, symmetry.     

Alcohol adducts of zinc dichloride: Molecular structure of [ZnCl2(THF){1-HOC(C6H11)2-2-NMe2C6H4}]

The aminoalcohols 1-HOCR₂-2-NMe₂C₆H₄ [R = Ph (1), R = C₆H₁₁ (2)] and 1-HOCPh₂CH₂-2-NMe₂C₆H₄ (3) react with ZnCl₂ in tetrahydrofuran to give the alcohol adducts [ZnCl₂(THF){1-HOCR₂-2-NMe₂C₆H₄}] [R = Ph (4), R = C₆H₁₁ (5)] and [ZnCl₂(THF){1-HOCPh₂CH₂-2-NMe₂C₆H₄}] (6). The complexes 4–6 were characterized by ¹H and ¹³C NMR spectroscopy, and 5 was also structurally characterized by X-ray crystallography.     

Chiral chelate phosphanes: XI. Application of cyclopentane-based C2 chiral bis(phosphane) ligands C5H8(PR2)2 to Pt---Sn-catalyzed styrene hydroformylation

Treatment of [(1,5-C₈H₁₂)PtCl(X)] (X=Cl, CH₃, CH₂CMe₃) with C₂ chiral cyclopentane-1,2-diyl-bis(phosphanes) C₅H₈(PR₂)₂, either as racemic mixtures or as resolved enantiomers, afforded the chelate complexes [C₅H₈(PR₂)₂Pt(Cl)(X)] (X=Cl: R=Ph (1), N-pip (2), OPh (3); X=CH₃: R=Ph (4), N-pip (5), OPh (6); X=CH₂CMe₃: R=Ph (7), N-pip (8), OPh (9); ‘N-pip’=N(CH₂)₅), (+)-[(1R,2R)-C₅H₈{P(OPh)₂}₂PtCl₂] [(R,R)-3], (−)-[(1S,2S)-C₅H₈{P(OPh)₂}₂PtCl₂] [(S,S)-3], (−)-[(1R,2R)-C₅H₈(PPh₂)₂Pt(Cl)(X)], and (+)-[(1S,2S)-C₅H₈(PPh₂)₂Pt(Cl)(X)] (X=CH₃: (R,R)-4, (S,S)-4; X=CH₂CMe₃: (R,R)-7, (S,S)-7). Reacting 4, 6, and 7 with AgO₃SCF₃ led to triflate derivatives [C₅H₈(PR₂)₂Pt(X)(OSO₂CF₃)] [X=CH₃: R=Ph (11), OPh (12); X=CH₂CMe₃: R=Ph (13)] with covalently bonded OSO₂CF₃ ligands. The unusual Pt₂ complex [μ-Cl{C₅H₈(PPh₂)₂PtCH₃}₂]O₃SCF₃ (14) containing an unsupported single Pt---Cl---Pt bridge was also isolated. In the presence of SnCl₂, complexes 1, 3, 4, 6, 7, and 9 are catalysts for the hydroformylation of styrene forming 2- and 3-phenylpropanal together with ethylbenzene. Except for 1, they also catalyze the consecutive hydrogenation of the primary propanals to alcohols. High regioselectivities towards 2-phenylpropanal (branched-to-normal ratios ≥91:9) were obtained in hydroformylations catalyzed by 3 and 4, for which the influence of varied CO/H₂ partial pressures, catalyst-to-substrate ratios and different reaction temperatures and times on the outcome of the catalytic reaction was also studied. When tin-modified complexes (R,R)-3, (S,S)-3, and (S,S)-4 were used as optically active Pt(II) catalysts, an only low stereoselectivity for asymmetric hydroformylation (e.e.<18%) was observed. The Pt---Sn complexes [C₅H₈(PR₂)₂Pt(CH₃)(SnCl₃)] [R=Ph (15), OPh (17)], resulting from SnCl₂ insertion into the Pt---Cl bonds of 4 or 6, undergo rapid degradation in solution, forming mixtures composed of [C₅H₈(PR₂)₂Pt(X)(Y)] with R=Ph or OPh and X/Y=Cl/SnCl₃ (16, 18), Cl/Cl (1, 3), and SnCl₃/SnCl₃ (19, 20), respectively. In the presence of SnCl₂, triflate complex 11 also becomes a catalyst for styrene hydroformylation and consecutive hydrogenation of the aldehydes to alcohols. The crystal structures of 11 complexes — 2, 5, 7, 8, 9, 10 (the previously prepared [C₅H₈{P(N-pip)₂}₂Pt(CH₂CMe₃)₂]), 13, 14, 16, (R,R)-3, and (S,S)-3 — were determined by X-ray diffraction.     

Steric and electronic effects in stabilizing allyl-palladium complexes of “P-N-P” ligands, X2PN(Me)PX2 (X = OC6H5 or OC6H3Me2-2,6)

The chemistry of η³-allyl palladium complexes of the diphosphazane ligands, X₂PN(Me)PX₂ [X = OC₆H₅ (1) or OC₆H₃Me₂-2,6 (2)] has been investigated.The reactions of the phenoxy derivative, (PhO)₂PN(Me)P(OPh)₂ with [Pd(η³-1,3-R′,R″-C₃H₃)(μ-Cl)]₂ (R′ = R″ = H or Me; R′ = H, R″ = Me) give exclusively the palladium dimer, [Pd₂{μ-(PhO)₂PN(Me)P(OPh)₂}₂Cl₂] (3); however, the analogous reaction with [Pd(η³-1,3-R′,R″-C₃H₃)(μ-Cl)]₂ (R′ = R″ = Ph) gives the palladium dimer and the allyl palladium complex [Pd(η³-1,3-R′,R″-C₃H₃)(1)](PF₆) (R′ = R″ = Ph) (4). On the other hand, the 2,6-dimethylphenoxy substituted derivative 2 reacts with (allyl) palladium chloro dimers to give stable allyl palladium complexes, [Pd(η³-1,3-R′,R″-C₃H₃)(2)](PF₆) [R′ = R″ = H (5), Me (7) or Ph (8); R′ = H, R″ = Me (6)].Detailed NMR studies reveal that the complexes 6 and 7 exist as a mixture of isomers in solution; the relatively less favourable isomer, anti-[Pd(η³-1-Me-C₃H₄)(2)](PF₆) (6b) and syn/anti-[Pd(η³-1,3-Me₂-C₃H₃)(2)](PF₆) (7b) are present to the extent of 25% and 40%, respectively. This result can be explained on the basis of the steric congestion around the donor phosphorus atoms in 2. The structures of four complexes (4, 5, 7a and 8) have been determined by X-ray crystallography; only one isomer is observed in the solid state in each case.     

Syntheses and crystal structures of linear coordinated complexes of Ag with the ligands C(PPh3)2 and (HC{PPh3}2)

The cationic complexes [({Ph₃P}₂C)Ag(C{PPh₃}₂)]X (2⁺, X = Cl, BF₄) with a linear arrangement of the ligands were obtained from the reaction of C(PPh₃)₂ (1) with the appropriate AgX in THF. The ³¹P NMR spectrum of the cation 2⁺ exhibits a doublet with J(Ag,P) = 15.3 Hz. The cation was also formed when the adduct O₂C ← 1 was allowed to react with AgX in CH₂Cl₂ in the first step as shown by ³¹P NMR; however, deprotonation of the solvent finally produced the cation (HC{PPh₃}₂)⁺, (H1)⁺ quantitatively. In the absence of coordinating anions, the tricationic complex [({Ph₃P}₂CH)Ag(CH{PPh₃}₂)](BF₄)₃ (3), containing the cation (H1)⁺ as ligand, could be isolated by reacting AgBF₄ with the salt (H1)(BF₄). All compounds were characterized by IR and ³¹P NMR spectroscopy; the structures of the compounds [2]Cl·1.25THF, 3·5CH₂Cl₂, 3·4C₂H₄Cl₂, and (H1)(BF₄) could be established by X-ray analyses.     

Unusual stabilization of cationic “M(η-allyl) (M = Pt, Pd) units by a dianionic cis-{Pt(C6F5)2(CCSiMe3)2} fragment

Chloride abstraction from [{M(η³ --- C₃H₅)Cl}_n] (M = Pt, n = 4 or M = Pd, n = 2) by (NBu₄)₂[cis-Pt(C₆F₅)₂(CCSiMe₃)₂] (1) gives rise to novel homo- and hetero-dinuclear zwitterionic derivatives (NBu₄) [{cis-Pt(C₆F₅)₂(CCSiMe₃)₂}M(η³-C₃H₅)] (M = Pt 2; M = Pd 3) which are formed by a M(η³-allyl)⁺ unit attached to both alkynyl ligands of the {cis-Pt(C₆F₅)₂(CCSiMe₃)₂}²⁻ fragment. The structure of 3 has been established by X-ray diffraction.