Coordination chemistry of alkali and alkaline earth cations—synthesis and X-ray structural analysis of sodium(picrate)-(1,10-phenanthroline)2

The complex Na(Pic)(PHEN)₂ (Pic = picrate, Phen = 1,10-phenanthroline) is unique in being a cluster with two independent Na ions in the asymmetric unit. Na(1) is seven-coordinated involving two N atoms of two Phen molecules (NaN, 2.492–2.622 Å), phenoxide O (NaO⁻, 2.381 Å) and an o-nitro-oxygen (NaONO, 2.584 Å) of Pic(1) and also to the phenoxide O (NaO⁻, 2.656 Å) of Pic(2). Na(2) is six-coordinated through four N atoms of the two other Phen molecules (NaN, 2.510–2.570 Å), phenoxide O (NaO⁻, 2.317 Å) and o-nitro-oxygen (NaONO, 2.592 Å) of Pic(2). Thus Pic(2) serves as a linkage residue between two clusters. The Phen molecules are planar and nearly perpendicular to each other in either cluster.     

Neutral mass-selected lead cluster beams

Neutral lead cluster beams with ultra-narrow size distribution were produced by neutralization of mass-selected lead cluster ions, Pb _n ⁺ withn≤12, in sodium vapor under near-resonant conditions. Absolute charge exchange cross sections were measured as a function of cluster size and are on the order of 40 Ų forn≥4. Possible fragmentation of the clusters associated with charge transfer was examined by translational spectroscopy. No indication of fragmentation was found.     

[Rh12Sb(CO)27]3-. an example of encapsulation of antimony by a transition metal carbonyl cluster

The reaction of Rh(CO)₂acac with triphenylantimony in the presence of cesium benzoate in tetraethylene glycol/dimethyl ether solution resulted in the selective formation of [Rh₁₂Sb(CO)₂₇]^3- (66% yield) after 3 h of contact time under ≈400 atm of carbon monixide and hydrogen (CO/H₂  1) at 140–160°C. The cluster has been isolated as the [Cs(18-Crown-6)₂]⁺, [(CH₃)₄]⁺, [(C₂H₅)₄N]⁺, (Ph₃P)₂N]⁺ and [PhCH₂N(C₂H₅)₃]⁺ salts. The [(C₂H₅)₄N]₃ [Rh₁₂Sb(CO)₂₇] complex has been characterized via a complete three-dimensional X-ray diffraction study. The complex crystallizes in the space group R$\text{3}$c with a  23.258(13) Å, c  22.811(4) Å, V  10 686 ų and p(calcd.)  2.334 g cm^-3 for mol.wt. 2503.66 and Z  6. Diffraction data were collected with an Enraf-Nonius CAD 4 automated diffractometer using graphite-monochromatized Mo-Kα radiation. The structure was solved by direct methods and refined by difference-Fourier and least-squares techniques. All non-hydrogen atoms have been located and refined: final discrepancy indices are R_f  3.5% and R_wf  4.6% for 3011 reflections. The anion's structure consists of twelve rhodium atoms situated at the corners of a distorted icosahedron with contacts of 2.807(1), 2.861(1), 2.874(1), 2.999(1), 3.017(1) and 3.334(1) Å and rhodium—antimony contacts of 2.712(0) Å. Rhodium—rhodium bond distances of 2.807 and 3.017 Å are in the range usually found for these complexes although a distance of 3.334 Å may be longer than expected from bonding interactions. The sum of the covalent radii of antimony and rhodium, 2.80 Å, is intermediate between the two observed RhSb contacts. The anion cluster structure is that of distorted icosahedron. This polyhedron has previously been found in [B₁₂H₁₂]^2- but not with transition metal clusters. A comparison between the structures of rhodium carbonyl clusters and boranes shows the occurrence of similar structural features. Applications of bonding theories based on the boranes, such as Wade's rules, to rhodium carbonyl clusters shows the extent in which these rules are obeyed.     

Palladium clusters Pd<Subscript>4</Subscript>(SR)<Subscript>4</Subscript>(OAc)<Subscript>4</Subscript> and Pd<Subscript>6</Subscript>(SR)<Subscript>12</Subscript> (R = Bu,Ph): Structure and properties

The structures of the Pd₄(SBu)₄(OAc)₄ (I) and Pd₆ (SBu)₁₂ (II) palladium clusters are determined by the X-ray diffraction method. For cluster I: a = 8.650(2), b = 12.314(2), c = 17.659(4) Å, α = 78.03(3)°, β = 86.71(2)°, γ = 78.13(3)°, V = 1800.8(7) ų, ρcalcd = 1.878 g/cm³, space group P \(\bar 1\), Z = 4, N = 3403, R = 0.0468; for structure II: a = 10.748(2), b = 12.840(3), c = 15.233(3) Å, α = 65.31(3)°, β = 70.10(3)°, γ = 72.91(3)°, V = 1767.4(6) ų, ρ calcd = 1.605 g/cm³, space group P \(\bar 1\), Z = 1, N = 3498, R = 0.0729. In cluster I, four Pd atoms form a planar cycle. The neighboring Pd atoms are bound by two acetate or two mercaptide bridges (Pd…Pd 2.95–3.23 Å, Pd…Pd angles 87.15°–92.85°). In cluster II, the Pd atoms form a planar six-membered cycle with Pd···Pd distances of 3.09–3.14 Å, the PdPdPd angles being 118.95°–120.80°. The Pd atoms are linked in pairs by two mercaptide bridges. The formation of clusters I and II in solution is proved by IR spectroscopy and calorimetry. Analogous clusters are formed in solution upon the reaction of palladium(II) diacetate with thiophenol.     

Reaction of hexanuclear niobium and tantalum halide clusters with mercury(II) halides. II. Semiconducting compounds with [Ta6Cl12]3+ unit

A series of paramagnetic clusters of the composition [(Ta₆Cl₁₂)Cl(H₂O)₅][HgX₄] · 9H₂)O (X = Cl, Br, I) has been prepared by the reaction of [Ta₆Cl₁₂]³⁺ methanol-water solutions with HgX₂ and NaX halides. The structure of [(Ta₆Cl₁₂)Cl(H₂O)₅][HgBr₄] · 9H₂O has been solved by X-ray diffraction in the cubic space group Fd 3m. Crystal data: a = 20.036(2) Å, V = 8043.0(1) ų, Z = 8, R = 0.048 (R_w = 0.051). The structure is composed of an octahedral [(Ta₆Cl₁₂)Cl(H₂O)₅]²⁺ cluster cation, tetrahedral [HgBr₄]²⁻ anion and crystal water molecules. The 2mm symmetry of the octahedron is reduced by the statistical distribution of the five water molecules, O(1), and chlorine, Cl(2), at the terminal coordination sites. Thus, the distances Ta-O(1) and Ta-Cl(2) are averaged to the value of 2.32(2) Å. The Ta-Ta and Ta-Cl(1) bond distances are 2.911(1) Å and 2.440(3) Å, respectively, whereas the Hg-Br bond distance is 2.564(3) Å. The cluster [(Ta₆Cl₁₂)Cl(H₂O)₅][HgBr₄] · 9H₂O is semiconducting with two levels governing conductivity with respective activation energies, E_al = 0.24 eV and E_a2 = 0.17 eV.     

Antiferromagnetic complexes with a metal-metal bond: XV. Antiferromagnetic heterometallospirane clusters [(CH3C5H4)2Cr2(μ-SCMe3)(μ3-S)2]2M (M = MnII,FeII): Synthesis and molecular structures

The reaction of (CH₃C₅H₄CrSCMe₃)₂S (Ia) with Cp₂Mn in boiling toluene (containing some THF) has been used to prepare a pentanuclear cluster, [(CH₃C₅H₄)₂Cr₂(SCMe₃)(μ₃-S)₂]Mn (II), which is antiferromagnetic and crystallizes into the monoclinic crystal system: space group Cc, a 26.540(10), b 9.208(3), c 21.595(9) Å; β 135.30(2)°, V = 3712.1 ų, Z = 4. According to X-ray analysis, cluster II contains a metallospirane core, Cr₄Mn, which appears to be strongly distorted, compared to its earlier studied cyclopentadienyl analogue [Cp₂Cr₂SCMe₃(μ₃-S)₂]₂Mn, due to the short intramolecular contacts CH₃…S (2.9–3.1 Å). The angle between the metal triangle planes of Cr₂Mn is 109.60°. Here, the two long CrMn bonds (3.019(3) and 3.104(4) Å) are combined with the shorter Cr Cr bond (2.651(6) Å) in one triangle and, vice versa, the less extended CrMn bonds (2.839(4) and 2.967(3) Å) are combined with a longer CrCr bond (2.726(6) Å) in the other triangle of Cr₂Mn. By the reaction of Ia with [CpFe(CO)₂]₂ (taken in the ratio of $\text{2}\text{1}$) in boiling toluene, the antiferromagnetic cluster [(CH₃C₅H₄)₂Cr₂(SCMe₃)(μ₃-S)₂]₂Fe (III) has been synthesized in which the same distortions as in cluster II are present, as revealed by X-ray analysis. In the metallospirane core of the molecule of III, the Cr₂Fe triangles make an angle of 113.84° with each other. In this cluster, the CrCr distances in the peripheral binuclear fragments (CH₃C₅H₄)₂Cr₂(μ-SCMe₃)(μ₃-S)₂ are practically equal (2.688(3) and 2.661(3) Å), whereas the FeCr bond lengths are markedly different (2.749(2) and 2.827(2) Å in on triangle and 2.910(2) and 2.969(2) Å in the other). The dependence of the geometries of clusters II and III on the steric effects of the methyl substituents in the cyclopentadienyl ligands and on the electronic effect of the central metal atom (Mn^II or Fe^II) is discussed.     

Cluster condensation reactions. The synthesis and crystal and molecular structure of Os6(CO)14(μ2-PPh2)2(μ3-S)3(μ4-S)

Thermal degradation of the cluster compound Os₃(CO)₈(PPh₂H)(μ₃-S)₂ (I) at 125°C leads to decarbonylation and formation of the new ligand bridged hexanuclear cluster Os₆(CO)₁₄(μ-PPh₂)₂(μ₃-S)₃(μ₄-S) (II) in 11% yield. Space Group: P$\text{1}$, No. 2, a 10.427(5), b 13.552(3), c 17.919(3) Å, α 84.87(2), β 75.41(3), γ 78.43(3)°, V 2399(2) ųZ = 2, _?calc 2.82 g cm^?3. The structure was solved by the heavy atom method and refined (3223 reflections) to the final residuals R = 0.042 and R_w = 0.036. The molecule consists of two sulfido bridged open triosmium clusters which are linked by a bridging sulfido ligand and a bridging diphenylphosphino ligand.     

A novel layered supramolecular compound containing 2D network of eight-member water clusters and terephthalato extended-bridged

A novel layered supramolecular compound [Ni(L)(TPHA)]·8H₂O, containing two-dimensional (2D) water clusters and terephthalato-bridged ligand, where L = 1,3,6,9,11,14-hexaazatricyclo[12.2.1.1^6,9] octadecane, TPHA = terephthalate dianion, has been synthesized and structurally characterized by spectroscopy and X-ray crystallography. The complex is neutral, in which the nickel(II) ions are bridged by the TPHA to form a one-dimensional (1D) infinite chain structure, and containing the eight-member water cluster. The presence of octameric water clusters have effectively increased the 1D coordination polymer to a three-dimensional layered structure. Every water cluster is connected strongly by a O–H···O hydrogen bond (range of the bonds between 2.724 and 3.056 Å). The complex crystallizes in monoclinic, space group P21/c with a = 9.788(3), b = 13.030(4), c = 11.646(4) Å, and β = 104.551(5)°.     

Isomery of [Re6S6Br8] and [Re6S5Br9] Units in a Rhenium Cluster Thiobromide: Experimental and Theoretical Approaches

The rhenium cluster thiobromide Cs_1.95(1)Re₆S_5.82(3)Br_8.19(3), belonging to the solid solution Cs₂Re₆S₆Br₈–CsRe₆S₅Br₉, crystallizes in the trigonal system (P31c, a = 10.001(5) Å and c = 14.676(5) Å). It is built up from [Re₆L ₈ ⁱ ]Br ₆ ^a cluster units in which sulphur and bromine are randomly distributed on inner position (Lⁱ). From the structural refinement performed using single-crystal X-ray diffraction data, the isomers of the [Re₆Sⁱ ₆Br ₂ ⁱ ] and [Re₆S ₅ ⁱ Br ₃ ⁱ ] cluster cores present in the structure have been unambiguously determined, due to the non-centro symmetry of the structure. Density functional theory calculations have been performed for all possible di- and tri-substituted isomers in order to confirm experimental analyses. Slight differences between the stability of di-substituted and tri-substituted cluster unit isomers built from Mo₆ cluster and Re₆ clusters are evidenced.     

Gas/gas and gas/wall average energy transfer from very low-pressure pyrolysis

It is shown that data obtained using very low-pressure pyrolysis (VLPP) on the pressure and temperature dependence of unimolecular rate coefficients of reactants with several reaction channels yield average energies transferred in gas/gas and gas/wall collisions (the wall being seasoned quartz at 800–1200 K). The downward average energy transferred, «ΔEå, for chlorocyclobutane/ethylene collisions is found to be 1600 cm^?1 at 970 K; «ΔEå for chlorocyclobutane/wall collisions varies from 5000 cm^?1 (wall efficiency β_w = 0.8) at 930 K to 3500 cm^?1 (β_w = 0.4) at 1150 K; similar values are found from published data on cycloheptatriene and cyclopropane-d₂. This indicates that the assumption of unit wall efficiency usually used in fitting VLPP experiments to RRKM theory needs revision.     

New pseudo-one-dimensional metals: M2Mo6Se6 (M = Na,In, K,TI), M2Mo6S6 (M = K,Rb, Cs), M2Mo6Te6 (M = In,TI)

We present a new series of ternary chalcogenides, derived from divalent molybdenum: M₂Mo₆X₆. These compounds crystallize in a hexagonal lattice with a ≈ 9 Å, c ≈ 4.5 Å, and space group $\text{P6}{}_3\text{m}$. The compounds are characterized by clusters (Mo₃)¹_∞ in the form of linear chains, resulting from a linear condensation of Mo₆ octahedral clusters. The (Mo₃)¹_∞ clusters are well separated from each other, with the shortest MoMo intercluster distance larger than 6 Å. The resulting pseudo-one-dimensional structures show remarkable anisotropy of physical properties.     

Sn4.4Mo24O38

The single‐crystal structure of tetratin tetracosa­molybdenum octatriaconta­oxide, Sn_4.4Mo₂₄O₃₈, contains infinite chains of centrosymmetric dioctahedral Mo₁₀ and centrosymmetric trioctahedral Mo₁₄ clusters. These clusters, as well as the O atoms, the arrangement of which derives from a closest‐packing with the layer sequence …ABAC…, form sheets parallel to the ac plane of the monoclinic unit cell. The Mo—Mo distances range from 2.6225 (7) to 2.8212 (9) Å and from 2.6270 (7) to 2.8365 (7) Å in the Mo₁₀ and Mo₁₄ clusters, respectively. The Mo—O distances vary between 1.949 (4) and 2.151 (4) Å in the Mo₁₀ cluster and between 1.938 (4) and 2.140 (4) Å in the Mo₁₄ cluster. The three crystallographically independent Sn²⁺ ions are off the centre of distorted oxy­gen octahedra.     

Synthesis and Crystal Structure of the Novel Compound Mg4.5Pr79.5Mo126O312 Containing Mo3, Mo7 and Mo19 Clusters

The synthesis and crystal structure of the novel reduced molybdenum oxide Mg_4.5Pr_79.5Mo₁₂₆O₃₁₂ are presented. This compound crystallizes in the trigonal space group R-3 m with a = 11.3061(2) Å, c = 58.242(1) Å, V = 6447.5(2) Å³, and Z = 1. Refinements yield R(F ²) = 0.0433 and wR(F ²) = 0.0931 for 2827 unique reflections. The structure is built up from alternating slabs made up of molybdenum forming Mo₃, Mo₇ and Mo₁₉ clusters, praseodymium and oxygen atoms, and slabs containing isolated MoO₆ octahedra. The Pr³⁺ cations are localized either within the slabs or at their borderlines to ensure the cohesion between the slabs. Of the six crystallographically independent sites occupy by the Pr³⁺ cations, two of them also contain randomly about 15% and 20% of Mg²⁺ cations while the remaining four are fully occupied by the Pr³⁺ cations.     

Collision induced fragmentation of mass-selected (CO2) n + clusters

The collisional velocity dependence of the cross sections for fragmentation of mass-selected (CO₂) _n ⁺ (n+2...7) clusters in collisions with Ar atoms is presented. Interesting structure can be observed in the cross sections which indicate that the collision occurs between the Ar atom and one CO₂ molecule within the cluster. The results may be explained by assuming that the collision leads to either vibrational excitation of a loosely bound CO₂ monomer which then leaves the cluster or excitation of the entire cluster to a dissociative state.     

Isolation of a water-stable B-centered hexazirconium bromide cluster,trans-[(Zr6BBr12)Br4(H2O)3]3−

(K₄Br)₂(Zr₆Br₁₈B), a B-centered hexazirconium cluster compound, is readily dissolved into aqueous media to form red solutions. ¹¹B NMR spectra of the cluster in aqueous LiBr solutions indicate that diamagnetic [Zr₆BBr₁₂]⁺ species are present as the result of one-electron oxidation of [Zr₆BBr₁₂]⁰ present in the precursor. Electrochemical measurements of the cluster in 6 M HBr solution shows that the diamagnetic [Zr₆Br₁₂]⁺ cluster is too weakly reducing to reduce protons. (H₃O)₃ {trans[(Zr₆BBr₁₂)Br₄(H₂O)₂]} · 13H₂O (1) was isolated when an aqueous HBr solution of the cluster was cooled to −20 °C. Crystallographic structural analysis of 1 (monoclinic, C2/c, a = 24.3557(7) Å, b = 10.0135(1) Å, c = 18.6388(6) Å, β = 92.370(2)°, Z = 4.) is reported. Both ¹¹B NMR spectroscopy and crystallography show that bromide coordinates the cluster much more weakly than chloride.     

Crystal structure of [{Cu(H2O)(en)2}{Cu(en)2}Re6Te8(CN)6]·3H2O

The reaction of Cs₄[Re₆Te₈(CN)₆]·2H₂O with Cu(en)₂Cl₂ in water affords crystals of a cluster complex [{Cu(H₂O)(en)₂}{Cu(en)₂}Re₆Te₈(CN)₆]·3H₂O. The structure of the compound is determined by single crystal X-ray diffraction (a = 10.8082(4) Å, b = 16.5404(6) Å, c = 24.6480(7) Å, β = 92.696(1)°, V = 4401.5(3) ų, Z = 4, space group P2₁/n, R ₁ = 0.0331, wR ₂ (all data) = 0.0652). In the complex, cluster [Re₆Te₈(CN)₆]^4? anions are linked by Cu²⁺ cations into zigzag chains through cyanide bridges. The coordination environment of the copper cations is complemented by ethylenediamine molecules. Each of the cluster anions is additionally coordinated by a terminal fragment {Cu(H₂O)(en)₂}.     

New compounds in the cesium sulfobromide rhenium octahedral cluster chemistry: syntheses and crystal structures of Cs4Re6S8Br6 and Cs2Re6S8Br4

The exploration of the CsReSBr system, in order to identify new phases based on octahedral cluster anions, has produced single crystals of Cs₄Re₆S₈Br₆ (1) (trigonal, space group P-6c2, a=9.7825 (3) Å, c=18.7843 (5) Å, V=1556.77 (1) ų, Z=2, density=5.09 g cm⁻³, μ=36.07 mm⁻¹) and Cs₂Re₆S₈Br₄ (2) (monoclinic, space group P2₁/n, a=6.3664 (1) Å, b=18.4483 (4) Å, c=9.3094 (2) Å, β=104.2618 (8)°, V=1059.69 (4) ų, Z=2, density=6.14 g cm⁻³, μ=45.83 mm⁻¹). These two compounds have been obtained by high-temperature solid state route. Their structures have been solved and refined from single crystal X-ray diffraction data. The structure of Cs₄Re₆S₈Br₆ presents isolated anionic cluster units inscribed in a (Cs⁺)₁₂ cuboctahedron and the one of Cs₂Re₆S₈Br₄ exhibits ReS^i-a,a-iRe inter-unit bridges. The framework of the latter presents then a strongly 1-D character.     

Synthesis and crystal structure of the octahedral cluster complex [Th(DMSO)8Cl][Re6Se7Cl7]

A cluster complex of the composition [Th(DMSO)₈Cl][Re₆Se₇Cl₇] has been obtained by interaction of ThCl₄ solution in DMSO with a water solution of K₃[Re₆Se₇Cl₇] and KCl. The compound crystallizes in the rhombic space group Pbcm with unit cell parameters a = 12.262(2) Å, b = 19.653(6) Å, c = 23.603(6) Å, V = 5688(2) ų, Z = 4, d _calc = 3.282 g/cm³. The structure is built from centrosymmetric cluster anions [Re₆Se₇Cl₇]^3? and complex cations [Th(DMSO)₈Cl]³⁺ possessing mirror-plane symmetry, half of the DMSO ligands being doubly disordered.     

Antiferromagnetic complexes with a metal—metal bond: VIII. Synthesis and structure of the antiferromagnetic heteronuclear cluster, “butterfly” (or “metal-chain”), (Cp4Cr2Ni2)(μ3-S)2(μ4-S)

By heating the mixture of solutions of (CpCrSCMe₃)₂S (I) in benzene and [CpNi(CO)]₂ in pentane followed by chromatography on alumina, dark cherry-red needles of the heteronuclear cluster (Cp₄Cr₂Ni₂)(μ³-S)₂(μ⁴-S) (II) were obtained, whose structure was established on the basis of a complete X-ray analysis. The crystals are rhombic, spatial group Pbca; a = 12.07(1), b = 18.50(2), c = 17.36(1) Å, Z = 8. The metallic skeleton of II has the “butterfly” or “metal-chain” structure with a direct CrCr bond (2.62(1) Å) and inequivalent CrNi bonds, 2.86(1) and 2.64(1) Å, while the Ni·Ni distance is nonbonding (4.34(1) Å). The NiCr₂ triangle planes produce a dihedral angle of 127°. The two μ³-bridged sulfur atoms locate under these triangles whereas the third sulfur atom is μ⁴-bridging coordinating all four metal atoms in the cluster with mean NiS and CrS distances of 2.29(1) and 2.25(1) Å, respectively. The Ni₂S₃ group is planar and almost perpendicular to the CrCr axis. Complex II is anti-ferromagnetic and its exchange parameter — 2J (418 cm^-1) is close to that found for the initial binuclear complex I (— 2J = 430 cm^-1 with a CrCr bond length of 2.689(8) Å). The role of the Ni coordination number in the generation of II is discussed.     

Synthesis and structure of a new molecular octahedral cluster complex Mo<Subscript>6</Subscript>Se<Subscript>8</Subscript>(Ph<Subscript>3</Subscript>P)<Subscript>6</Subscript>·2H<Subscript>2</Subscript>O

Mo₆Se₈(Ph₃P)₆·2H₂O cluster complex has been synthesized and its structure has been defined. The compound is triclinic, space group P1ˉ, with unit cell parameters a = 14.3356(5) Å, b = 15.7882(4) Å, c = 25.3949(8) Å, = 95.9750(10)°, β = 91.1030(10)°, γ= 112.2570(10)°, V = 5279.8(3) ų, Z = 2, ρ_calc = 1.772 g/cm³. The complex has a molecular structure. The molybdenum atoms of the {Mo₆Se₈} cluster nucleus are coordinated by the phosphorus atoms of triphenylphosphine molecules. Original Russian Text Copyright ? 2007 by Yu. V. Mironov, Zh. S. Kozhomuratova, D. Yu. Naumov, and V. E. Fedorov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No. 2, pp. 389–393, March–April, 2007.