Acyl-platinum(II) and -palladium(II) complexes derived from 2-hydroxybenzaldehyde derivatives. X-ray structure of [Pt(OC6H4CO) (P(p-CH3C6H4)3)2]

Platinum(II) and palladium(II) complexes containing chelating acyl ligands have been synthesized from salicylaldehyde, 2-hydroxynaphthaldehyde and 2-hydroxy-3-methoxybenzaldehyde. The platinum(II) complexes [Pt(acyl)L₂], acyl  OC₆H₄CO, OC₁₀H₆CO, O(m-CH₃OC₆H₃CO), L  tertiary phosphine, 1/2 diphenylphosphinoethane, can be isolated with both monodentate and chelating diphosphines, whereas for palladium only the compounds with chelating phosphines are readily obtainable. The reactions of [Pt(OC₆H₄CO)L₂] with HCl afford trans-[PtCl(OHC₆H₄CO)L₂], L  monodentate tertiary phosphine and cis-[PtCl(OHC₆H₄CO)L₂], L2  1,2-bis-diphenylphosphinoethane, in which the metal—carbon bond remains intact. The structure of [Pt(OC₆H₄CO)-(P(p-CH₃C₆H₄)₃)₂] has been determined by X-ray diffraction methods and found to have the expected square planar structure. Some relevant bond lengths and angles are: PtP; 2.271(4) and 2.348(5) Å; PtC; 1.96(2) Å and PtO; 2.07(1) Å; PPtP  101°, CPtO  82°.     

Crystal and molecular structure of tricyclopentadienyltetrahydrofuranuranium(III), (η5-C5H5)3U·OC4H8

Tricyclopentadienyltetrahydrofuranuranium(III), (η⁵-C₅H₅)₃U·OC₄H₈, crystallizes in the centrosymmetric monoclinic space group P2₁/n with a 8.248(3), b 24.322(17), c 8.357(4) Å, β 101.29(5)°, V 1644.0 ų and ρ(calc) 2.04 g cm^?1 for Z = 4 and mol.wt. 595.0. Diffraction data (Mo-K_α, 2θ(max) 45°) were collected on an Enraf-Nonius CAD4 diffractometer and the structure was refined to R_w(F) 4.7% for those 1530 reflections having I > 2σ(I). The molecule consists of a distorted tetrahedral arrangement of THF and (η⁵-C₅H₅) ligands with CpUCp angles in the range 110.4–122.4° and CpUO angles between 90.2 and 106.0°. Individual uranium-carbon distances range from 2.76(2) to 2.82(2) Å and average 2.79[1] Å. The uranium-oxygen distance of 2.551(10) Å suggests a 10-coordinate U³⁺ radius of 1.20 Å in this class of compounds.     

Kristall- und molekülstruktur von hexaphenyldistannylselenid (C6H5)3SnSeSn(C6H5)3

The crystal and molecular structure of hexaphenylditin selenide (C₆H₅)₃SnSeSn(G₆H₅)₃ was determined by X-ray diffraction data and was refined to R  0.055. The compound is monoclinic, space group P2₁, with a  9.950(4), b  18.650(7), c  18.066(6) Å, β  106.81(4)°, Z  4. The two molecules in the asymmetric unit differ slightly in their conformations, both having approximate C₂ symmetry. Bond lengths and angles are: SnSe 2.526 (2.521(3) ? 2.538(3)) Å; SnC 2.138 (2.107(16)?2.168(19)) Å; SnSeSn 103.4(1)°, 105.2(1)°. There are only slight angular distortions at the SnSeC₃ tetrahedra (SeSnC angles: 104.3(5)?114.8(4)°). The bond data indicate essentially single bonds around the Sn atoms.     

Synthesis and structure of the heterotrinuclear chromium-palladium clusters (RC5H4CrCl)2-(μ3S)(μ-SCMe3)2Pd(PPh3) with ferromagnetic exchange interactions over the CrSCr system

Reactions of (RC₅H₄)₂Cr₂(SCMe₃)₂S(I, R = H; II, R = Me) with (PPh₃)₂PdCl₂ in benzene at 20°C gives trinuclear complexes (RC₅H₄)₂Cr₂Cl₂(μ₃-S)(μ-SCMe₃)₂Pd(PPh₃)(III, R = H; IV, R = Me). The structure of IV as a monobenzene solvate is established by an X-ray analysis (black-green triclinic crystals space group P$\text{1}$ with a = 11.403(4), b = 14.933(5), c = 14.131(5) Å, α = 99.13(3), β = 112.72(3), γ = 95.65(3)°, V = 2201.6 Å, Z = 2; IV·C₆H₆). The structure was solved by direct methods and refined in an anisotropic approximation to R = 0.046, R_w = 0.058 for 7643 reflections with I ? 2σ(I). In the molecule of IV metal atoms are separated by non-bonding distances (Cr … Cr 4.079(I), Cr … Pd 3.230(I) and 3.380(I) Å) but linked by the bridging tridentate sulphur atom (CrS 2.339(2) and 2.329(2), PdS 2.327(2) Å), and two SCMe₃ groups between Pd and Cr (CrS 2.396(2) and 2.403(2), PdS 2.350(2) and 2.381(2) Å, Cr?Pd 85.14(6) and 89.92(6)°). The Cl atoms are transferred from Pd to Cr atoms (CrCl 2.308(2) Å) and being terminally coordinated are in trans-positions to each other (as well as η-CH₃C₅H₄ rings) with respect to the Cr₂Pd plane. Cr atoms in III and IV exhibit ferromagnetic exchange interactions over the Cr?Cr system (+2J = 28 and 11 cm^?1, respectively).     

A dichromium(II) compound with an elongated metal-metal bond: Cr2(oxindolate)4(oxindole)2

The title compound has been prepared by reaction of (C₅H₅)₂Cr with oxindole (indole with CO in place of CH₂ at the 2-position). Red single crystals belong to space group P2₁/c with a = 10.107(4) Å, b = 22.496(7) Å, c = 9.210(3) Å, β = 93.26(3)°, V = 2091(2), and Z = 2. The centrosymmetric molecule has a CrCr distance of 2.495(4) Å. The mean CrO and CrN distances for the bonds to bridging oxindolate anions are 2.024(7) and 2.065(8) Å, respectively. There is an oxindole molecule bound at each end with a CrO axial bond of length 2.341(8) Å and a hydrogen bond from the oxindole NH group to an equatorial oxygen atom of length 2.83(1) Å. The significance of this compound with respect to CrCr bonding is discussed.     

Crystal and molecular structure of (η3-allyl)carbonylchlorobis(dimethylphenylphosphine)- iridium(III) hexafluorophosphate, [Ir(η3-C3H5)Cl(CO)(P(CH3)2(C6H5))2][PF6

The structure of (η³-allyl)carbonylchlorobis(dimethylphenylphosphine)-iridium(III) hexafluorophosphate, [Ir(η³-C₃H₅)Cl(CO)(P(CH₃)₂(C₆H₅))₂][PF₆], has been determined from three-dimensional X-ray data to add support for a proposed mechanism of the oxidative addition of allyl halides to IrX(CO)(PR₃)₂ (X = halide). The compound crystallizes in space group C⁵_2h-P2₁/c with four formula units in a cell of dimensions a = 11.027(1), b = 12.230(2), c = 19.447(5) Å, and β = 103.16(2)⁰. Least-squares refinement of the structure has led to a value of the conventional R index (on F) of 0.066 for the 3018 independent reflections having F²₀>3—(F²₀). The crystal structure consists of discrete, monomericions. The hexafluorophosphate anion is disordered. The coordination geometry around the iridium atom may be described as octahedral, with the chloro ligand trans to the carbonyl group and each phosphorus atom trans to a terminal carbon of the allyl group. Structural parameters: Ir—P = 2.366(4), 2.347(3);Ir—Cl = 2.389(3); Ir—C(allyl) = 2.28(1), 2.24(1),2.25(1); Ir—C (carbonyl) = 1.85(1) Å; P—Ir—P = 105.7(1); C(terminal)—Ir—C(terminal) = 66.2(8); C—C—C = 125(2)^o. The allyl group makes an angle of 126^o with the P—Ir—P plane. Correlations between geometric structure and number of d electrons are noted among several M—C₃H₅-complexes, and are interpreted in the light of theoretical models of the M—C₃H₅- bond.     

Fulvene—platinum complexes: x-ray crystal structure of [Pt(η2-C5H4CPh2)(PPh3)2]

Bis(cycloocta-1,5-diene)platinum reacts with 2,3,4,5-tetraphenylfulvene to afford the complex [Pt(η²-CH₂C₅Ph₄)(cod)] (cod  C₈H₁₂) in which the metal atom is coordinated to the exo-cyclic double bond of the fulvene. Related compounds [Pt(η²-CH₂C₅Ph₄L₂] (L  PPh₃, PMePh₂, PMe₂Ph, AsPh₃ or CNBu^t have also been prepared and characterised. Reaction of the complexes [Pt(C₂H₄)₂(L)] (L  P(cyclo-C₆H₁₁)₃, PPh₃ or AsPh₃) with 2,3,4,5-tetraphenylfulvene yields the compounds [Pt(C₂H₄)(η²-CH₂C₅PH₄)(L)]. NMR data for the new species are reported and discussed. 6,6-Diphenylfulvene reacts with [Pt(cod)₂] and PPh₃ ($\text{1}\text{2}$ mol ratio) to give the complex [Pt(η²-C₅H₄CPh₂)-(PPh₃)₂] in which the metal atom is bonded to carbon atoms C(2) and C(3) of the fulvene ring. This was established by an X-ray diffraction study. Crystals are monoclinic, space group P2₁/n, with Z  4 in a unit cell of dimensions a  13.761(4), b  21.653(13), c  17.395(6) Å, β,  104.46(2)°. The structure has been solved and refined to R  0.064 (R′  0.064) for 3139 independent diffracted intensifies measured at room temperature. The platinum atom is in a trigonal environment formed by the two ligated phosphorus atoms and the CC bond of the fulvene which is elongated to 1.52(3) Å. The c₅ fulvene ring is planar, and makes an angle of 108° with the coordination plane around the platinum. In this plane the metal atom is slightly asymmetrically bonded with PtC 2.15(2) and 2.24(2) Å, and PtP 2.280(6) and 2.301(6) Å.     

The crystal structure of Mn(NO)3P(C6H5)3: The first x-ray analysis of a mononuclear metal trinitrosyl complex

The structure of Mn(NO)₃PPh₃ has been analyzed by single-crystal X-ray diffraction. It shows a tetrahedral geometry with essentially linear nitrosyl groups, and an eclipsed configuration around the MnP bond. Average distances and angles are: MnN 1.686(7) Å, MnP 2.315(2) Å, NO 1.165(10) Å, PC 1.815(4) Å, MnNO 177.2(7)°, PMnN 103.6(2)°, NMnN 114.7(4)°. Final R factor 7.3% for 2064 non-zero reflections. The structure of the five-coordinate nitrito complex Mn(NO)₂(ONO)(PEt₃)₂ is also mentioned briefly.     

Synthesis of 1,2-ethanediylbis(diphenyl-phosphonium)-PH,P′H′ hexachloromolybdate(III) I and nonachlorodimolybdate(III) II. The crystal structure of (dppeH2)3[MoCl6]2·12h2O

Two compounds of the formulae (dppeH₂)₃[MOCl₆]₂ ·12H₂O I and (dppeH₂)₃[Mo₂Cl₉]₂II are described. For compound I, which proved to be active in olefin epoxidation, the crystal structure was determined. The rose-pink crystals are triclinic, space group P$\text{1}$ with a = 13.715(9), b₃ = 14.686(7), c = 12.512(7) Å, α = 109.56(4), β = 97,98(4) and γ = 91.27(5)°, V = 2345 Å, D_m = 1.42 and D_c = 1.44 gcm^?3, Z = 1. Block-diagonal least squares refinement of the structure has led to a final value of the conventional R factor of 0.049 for the 3914 independent reflections with I > 3σ(I). Bond distances are in the range: MoCl 2.439(2)–2.469(2) Å, and PC 1.771(9)–1.806(8) Å.     

The crystal and molecular structure of dicarbonylbis(diphenylethylphosphine) platinum(0) Pt(CO)2[P(C6H5)2(C2H5)]2

The complex dicarbonylbis(diphenylethylphosphine)platinum, Pt(CO)₂[P(C₆H₅)₂(C₂H₅)]₂, crystallizes in either of the enantiomorphous space groups P3₁21 (No. 152) and P3₂21 (No. 154) with cell dimensions a = 10.64(1), c = 22.06(1) Å, U = 2163 ų; p_c = 1.564 g/cm³ for Z = 3, p_m = 1.55(3) g/cm³. The intensities of 1177 independent reflections have been determined by counter methods with MoKα monochromatized radiation. The structure has been solved by the heavy atom method. The refinement, carried out by full-matrix least squares down to a final R factor of 0.042, has enabled the absolute configuration of the crystal sample (space group P3₁21) to be ascertained. The molecule is roughly tetrahedral, and has the metal atom lying on a two-fold axis of the cell. Bond parameters are: PtC = 1.92(2) Å, PtP = 2.360(4) Å, CPtC = 117(1)° and PPtP = 97.9(2)°. The PtC₂ and PtP₂ moieties make a dihedral angle of 86.0(3)°. The overall C₂ symmetry of the molecule is probably only a statistically averaged situation, a disorder in the PtCO interactions being apparent from the orientations of the thermal ellipsoids of the C and O atoms.     

Structural studies of complexes containing the coordinated methyldisulphido ligand: The crystal structure of [Os (η2-S2CH3) (CO)2 (P (C6H5)3)2] ClO4·12 C6H6.

Crystal and molecular structures of the title compound have been determined from a three-dimentional X-ray analysis usinq diffractometer data. The crystals are triclinic, space group P$\text{1}$, with Z = 2 in a unit cell of dimensions a = 14.23(1), b = 17.30(1), c = 10.44(1) Å, α = 102.1(2), β = 102.7(2), γ = 105.5(2)°. Full matrix least squares refinement has given a final R-factor of 0.060 for 4628 reflections for which I > 3σ(I).The crystal structure consist of discrete cations and anions, together with benzene molecules of crystallisation which are situated about the crystallographic centres of symmetry and serve a purely space-filling role. In the cation coordination about the osmium atom is that of a distorted octahedron, comprising the two triphenylphosphine groups (mutually trans), the two carbonyl groups (mutually cis) and the dihapto S₂Me group. The Os-P distances of 2.420 and 2.419(3) Å are normal. The S₂Me group is nearly symmetrically coordinated with Os-S(l) 2.426(4)Å and Os-S(3) 2.442(4) Å. Other bonds and angles in this ligand are S(1)-S(2) 2.022(7) Å, S(1)-CH₂ 1.81(2) Å, and S(2)-S(1)-CH₃ 105.4(6)°. The observed geometry is similar to that in [Ir(S₂) (Ph₂PCH₂CH₂PPh₂)₂Cl.Ch₃CN.     

Reaction of alkenes with trans-MeOIr(CO)(PPh3)2. Crystal and molecular structure of the pentacoordinate alkoxy-alkene iridium(I) complex,MeOIr(CO)(PPh3)2(TCNE)

The reaction of trans-MeOIr(CO)(PPh₃)₂ with TCNE (tetracyanoethylene) gives rise to the stable adduct MeOIr(CO)(PPh₃)₂(TCNE), the structure of which has been determined via a single-crystal X-ray diffraction study. This complex crystallizes in the centrosymmetric orthorhombic space group Pbca (D¹⁵_2h; No. 61) with a 17.806(4), b 20.769(4), c 20.589(6) Å, V 7614(3) ų and Z = 8. Diffraction data (Mo-K_α, 2θ = 5–45°) were collected on a Syntex P2₁ automated four-circle diffractometer and the structure was solved and refined to R_F 6.2% for 3502 data with |F₀| > 3σ(|F₀|) (R_F 4.3% for those 2775 data with |F₀| > 6 σ(|F₀|)). The central iridium atom has a distorted trigonal bipyramidal coordination geometry in which the methoxy group (Ir-OMe 2.057(8) Å) and carbonyl ligand (Ir-CO 1.897(14) Å) occupy axial sites with ∠MeOIrCO 174.7(4)°. The two triphenylphosphine ligands occupy equatorial sites (IrP(1) 2.399(3), IrP(2) 2.390(3) Å, ∠P(1)IrP(2) 110.32(11)° and the TCNE ligand is linked in an η² “face-on” fashion with the olefinic bond parallel to the equatorial coordination plane (IrC(4) 2.176(10), IrC(7) 2.160(12) Å) and lengthened substantially from its value in the free olefin (C(4)C(7) 1.539(17) Å).     

Die konformation des μ-bis[tetracarbonylrhenium(I)]-bis-[tetracarbonyl(trithiocarbonato)rhenium(I)], eines überraschenden reaktionsproduktes bei der umsetzung von CF3Re(CO)5 mit CS2

The molecular structure of [(C₆H₅)₃P]₂Pd(C₃H₄) has been determined from three-dimensional X-ray diffraction data. The crystal belongs to the triclinic system, space group P$\text{1}$, with two formula units in a cell of dimensions: a = 19.475(2), b = 10.204(2), c = 18.341(2) Å, α = 108.46(2), β = 85.46(1), and γ = 118.80(1)°.One of the olefinic bonds of allene is coordinated to the palladium atom: PdC(1) = 2.118(9) and PdC(2) = 2.067(8) Å. The coordinated allene is no longer linear, the C(1)C(2)C(3) angle being 148.3(8)°. The C(1)C(2) distance is 1.401(11) Å, whereas the uncoordinated bond remains unchanged [C(2)C(3) = 1.304(12) Å]. The Pd, P(1), P(2), C(1) and C(2) atoms lie almost in the same plane.     

Crystal and molecular structure of [η5-C5(CH3)5]Co(O2C6H4), a cobalt(o-catecholate) complex

[η⁵-C₅(CH₃)₅]Co(O₂C₆H₄) crystallizes in the orthorhombic space group Pnma with a 12.942(4), b 12.902(4), c 8.543(3) Å, V 1426(1) ų, and Z = 4. Least-squares refinement of 1688 independent observed reflections, F(_obs) ? 2.5σ(F_obs), gives R_F 3.79 and R_wF 3.72%. The cyclopentadienyl ring contains two short (1.412(3) Å) and three longer (〈av〉 1.430(4) Å) CC bond lenghts, consistent with a slight preference for diolefin bonding. The O₂C₆H₄ fragment is best described as a catecholate with a CO bond distance of 1.338(3), and a CoO distance of 1.837(2) Å.     

Kristall-und molekülstrukturen zweier modifikationen de hexaphenyldigermylsulfids (C6H5)3GeSGe(C6H5)3

en Two differnt crystal modifications of hexaphenyldigermanium sulfide (C₆H₅GeSGe(C₆H₅)₃ (I and II were obtained by crystallization from hot benzene/methanol or form ethanol at 20°C. Single crystal X-ray structural analyses for both I (low temperature data at ?130°C) and II (at 20°C) (I, R = 0.046; II, R = 0.048) were performed. I is monoclinic, P2¹/c, with a = 11.020(3), b = 15.473(3), c 18.606(3) »,π = 106.92(2)°, Z = 4; II is orthorhombic, P2₁2₁2₁, with a = 2.617(2), b = 17.345(3), c = 18.408(3) », Z = 4.The molecules have different conformeric structures with respect to a rotation of the (C₆H₆)₃Ge groups around the Ge bonds with very similar bond lenghts and angles. Bond data for I(II) are: GeS 2.212(1) and 2.261(1) » (2.227(2) and 2.240(2) »); GeC 1.933(4) ? 1.971(4), mean 1.945(5) » (1.931(7)?1.954(7), mean 1.943(4) »); GeSGe 111.2(1)° (110.7(1)°). The Ge bond lenghts are comparable to those in thiogermanates and do not indicate significant π-bond contributions.     

Barreleneiridium(I) complexes. Crystal structures of [Ir(Me3TFB)(η6-C6H4Me2)]ClO4 and [Ir(TFB)(η5-PhNPh2)]BF4·CH2Cl2 (TFB = tetrafluorobenzobarrelene)

A new series of cationic areneiridium(I) complexes of formula [Ir(barrelene)(arene)]⁺ or [Ir(barrelene)(PhNRPh)]⁺ (R= Ph or H) have been synthesized from neutral iridium complexes of the type [IrY(barrelene)]_x (barrelene = Me₃TFB, Y = Cl or OMe (x = 2), Y = acac (x = 1); barrelene = TFB, Y = OMe (x = 2), Y = acac (x = 1)). The crystal structures of [Ir(Me₃TFB)(1,4-C₆H₄Me₂)]ClO₄ and [Ir(TFB)(PhNPh₂)]BF₄·CH₂Cl₂ have been determined by X-ray diffraction. They crystallize in the space groups Pbca and Pna2₁ respectively with lattice constants of 17.6947(11), 15.8072(10), 16.0019(11) Å and 9.8059(2), 20.8097(9), 14.3367(4) Å. Final R factors were 0.063 and 0.042 for the observed data. Both complexes show a staggered arrangement between the arene and the TFB moieties and deviation from planarity of the coordinated arene ligands. In the second complex the IrC and NC distances, the CNC angle, the type of arene puckering, and the spectroscopic data indicate a distortion of the coordinated arene towards a η⁵-coordinated iminocyclohexadienyl form.     

Die molekül- und kristallstruktur von thallium-tris(bistrimethylsilylamin), Tl[N(SiMe3)2]3

The molecular and crystal structure of tris(bistrimethylsilylamin)thallium was determined by means of single-crystal X-ray spectroscopy: in the space group P$\text{3}$1c with a = 16.447(7), c = 8.456(7) Å; and D_c = 1.149 g cm^?3 two molecules are located in the unit cell. The compound is isomorphous to the analogues Fe[N(SiMe₃)₂]₃ or Al[N(SiMe₃)₂]₃, respectively, which show a propellar-twist of the Si₂N-groups versus the plane of the metal atom and the three nitrogen-atoms: Tl(N)₃/Si₂N 49.1°; SiNSi 122.6°; NSiC 111.8°; CSiC 107.1°; TlN 2.089 Å;; SiN 1.738 Å;; $\text{SiC}$ 1.889 Å;.     

Die kristall- und molekúlstruktur der dimeren dimethylaluminium- und dimethylgallium-N,N′-dimethylacetamidine [(CH3)2M(NCH3)2CCH3]2 (M = Al,Ga)

Dimethylaluminium- and dimethylgallium-N,N′-dimethylacetamidine (I and II) are doubly associated forming a puckered eight-membered ring. They crystallize isostructurally in the monoclinic space group P2₁/c with two dimers per unit cell. The lattice constants of I are a 8.187, b 7.266, c 14.778 Å, β 103.58° and those of II a 8.163, b 7.277, c 14.835 Å, β 103.46°. The MN and the NC bond lengths within the rings are nearly equal, their mean values are for I: AlN 1.925 Å, CN 1.330 Å and for II: GaN 1.979 Å, CN 1.335 Å. This is also true for the exocyclic bond lengths with average values AlC 1.975 Å, NC 1.474 Å, CC 1.509 Å (for I) and GaC 1.998 Å, NC 1.484 Å and CC 1.507 Å (for II). The metal atoms are tetrahedrally coordinated, and the distortion is only slight. The final R-values are 0.034 and 0.056, respectively.     

Synthesis and crystal chemistry of NH3(MoO3)3

NH₃(MoO₃)₃ crystallizes with hexagonal symmetry, space group $\text{P6}{}_3\text{m}$, lattice constants a = 10.568 Å, c = 3.726 Å, and Z = 2. The crystal structure has been determined by Patterson synthesis and refined assuming isotropic temperature factors to a final conventional R value of 0.085. The structure shows a three-dimensional arrangement built up of double chains of distorted MoO₆ octahedra, parallel to the [001] direction. The octahedral double chains are linked among each other through common oxygen atoms. In addition to the shared oxygen atoms, each molybdenum is coordinated to one terminal oxygen. MoO distances range from 1.645 to 2.378 Å and OMoO angles from 74.3 to 114.3°. These results are consistent with the fact that molybdenum in high-valence states shows octahedral coordination with terminal oxygens.     

Cluster chemistry XXIV. X-ray structure of H4 Ru4(CO)9(PMe2 Ph)[P(OC6H4 Me-p)3]-[P(OCH2)3CEt], a chiral cluster complex containing four different ligands

The X-ray structure of H₄Ru₄(CO)₉(PMe₂Ph)[P(OC₆H₄Me-p)₃][P(OCH₂)₃CEt], a chiral cluster complex, has been determined. The complex is triclinic, space group P$\text{1}$, a 19.812(7), b 14.299(4), c 10.323(4) Å, α 100.09(3), β 98.18(3), γ 102.23(3)°. The unit cell contains an enantiomeric pair of molecules. The Ru₄ core contains two short (av. 2.785 Å) and four long (2.967 Å) RuRu separations with approximate D_2d symmetry. RuP separations are 2.254(6) Å [to P(OCH₂)₃CEt], 2.270(6) Å [to P(OC₆H₄Me-p)₃] and 2.326(7) Å [to PMe₂Ph]; all P-donor ligands are trans to short RuRu vectors.