Binuclear complexes of a new hexadentate macrocyclic ligand. The crystal and molecular structure of [LCu2(CH3CO2)2](ClO4)2·5H2O

The 30-membered hexaaza macrocylic ligand, L (L=3,7,11,18,22,26-hexaazatricyclo-[26.2.2.2^13,16]tetratriaconta-1(31),13(33),14,16(34),28(32),29-hexaene), is capable of forming binuclear complexes with the divalent transition metal ions Ni, Cu and Zn. The two metal ions are bound by the two dipropylenetriamine units of the macrocycle. Extra coordination sites on the metal ions can be occupied by exogenous ligands such as acetate, chloride and thiocyanate. The crystal structure of one of the di-copper complexes is described: [LCu₂(CH₃CO₂)₂](ClO₄)₂·5H₂O crystallizes in the monoclinic space group P2₁/c (No. 14), with a=9.369(2), b=17.644(3), c= 27.466(3) Å, β=92.90(1)°, U=4534.7 ų and Z=4. The Cu1···Cu2 separation is 8.40(3) Å. The access for potential exogenous bridging ligands, to the cavity between the copper ions, is somewhat restricted by the two phenyl units of the macrocycle which appear almost parallel in the structure. The redox potential of the couple L(Cu²⁺)₂/L(Cu⁺)₂, recorded by cyclic voltammetry for the chloride adduct, [LCu₂Cl₂]Cl₂·5H₂O, is −0.061 V versus SCE in DMF.     

Synthesis and crystal structure of the MgCl2(CH3COOC2H5)2· (CH3COOC2H5) adduct

The reaction of α-MgCl₂ with boiling ethyl acetate affords MgCI₂(CH₃COOC₂H₅)₂· (CH₃COOC₂H₅), which is obtained as crystals suitable for X-ray analysis only from the mother liquor. M=315.5, orthorhombic, space group P2₁22₁ (No. 18), a=25.077(3), b=8.616(1), c=7.345(1) Å, V=1587.0(3) ų, Z=4, D_x=1.32 g cm⁻³,λ A(Mo Kα)=0.71069 Å, μ=4.17 cm⁻¹, F(000)=664, T=298 K, observed reflections: 1667, R=0.059 and R_w=0.069. The structure is composed of polymeric chains of MgCl₂(CH₃COOC₂H₅₎₂ and the ethyl acetate molecules occupy a mutually trans position.     

Preparation, X-ray structure and solution behavior of [Ag(9-EtGH-N7)2]NO3·H2O (9-EtGH=9-ethylguanine)

The preparation and X-ray structure of [Ag(9-EtGH-N7)₂]NO₃·H₂O(9-EtGH=neutral 9-ethylguanine) is reported. The compound crystallizes in the triclinic system, space group P with a=7.063(6), b=7.153(3), c=11.306(10) Å, α=83.36(6), β=76.66(7), γ=81.44(6)°. The cation is centrosymmetric with Ag(I) coordinated via two N7 positions and Ag---N7 bond lengths of 2.11(1) Å. Applying ¹⁰⁹Ag NMR spectroscopy, complex formation constants for both the 1:1 complex (log β₁=0.6) and the title compound (log β₂=1.6) in Me₂SO have been determined.     

Synthesis and structure of an organosamarium aryloxide complex, (C5 Me5)2 Sm(OC6HMe4-2,3,5,6)

Bis(pentamethylcyclopentadienyl)samarium bis- (tetrahydrofuranate), (C₅Me₅)₂Sm(THF)₂, reacts with 2,3,5,6-tetramethylphenol in toluene to yield (C₅Me₅)₂Sm(OC₆HMe₄-2,3,5,6). The compound crystallizes in the space group P2₁/c with a = 8.725(3) Å, b=18.821(6) Å, c=18.461(6) Å, β= 111.17(2)°, V = 2827(2) ų and D_c=1.340 g cm⁻³ for Z = 4. Molecules of the aryloxide complex are monomeric and exhibit a bent metallocene structure with a nearly linear Sm---O---C(aryloxide) linkage: Sm---O = 2.13(1) Å, O---C = 1.29(2) Å, and Sm---O---C = 172.3(13)°. Reaction of the samarium complex with phenyllithium produces the previously- characterized species (C₅Me₅)₂Sm(C₆H₅)(THF).     

The X-ray structure analysis of bis-2,2′,N,N′-bipyridyl ketone cobalt(III) nitrate dihydrate

An X-ray structural analysis of bis-2,2′,N,N′-bipyridyl ketone cobalt(III) nitrate dihydrate, CoC₂₂H₂₀N₄O₄⁺· NO₃⁻·2H₂O,M_r=559.38 g/mol, P , a=8.862(2), b=16.195(3), c=8.772(2) Å, α=103.54(2), β=95.74(3), γ=105.07°, V=1164.4(4) ų, Z=2, D_x=1.595 g/cm³, Mo Kα radiation (λ=0.71073 Å), μ=7.8 cm⁻¹ and R=0.079, revealed a Co(III) cation in a slightly distorted octahedral environment. The structure reveals that the ligand di-2-pyridyl ketone (dpk) has undergone a hydration reaction across the ketone double bond and one of the hydrate oxygen atoms coordinated to the metal forming a tridentate chelate. This new Co(dpk-hydrate)₂⁺ complex displays the least distorted geometry yet reported for either 1:1 or 1:2 (metal:ligand) complexes. A geometry optimization using the INDO model Hamiltonian as implemented in the program ZINDO was performed on the title complex with the Co³⁺ modeled as a singlet. The result of the computation corroborates the geometry of the title complex as that expected for Co³⁺.     

A new structural type for a binuclear chloride-bridged copper(II) complex. Structural and magnetic characterization of di-μ-chloro-chloropentakis(benzimidazole) dicopper(II) monochloride tetrahydrate, [Cu2Cl3(C7H6N2)5]Cl·4H2O

The synthesis, crystal structure determination and magnetic properties of a new five-coordinated unsymmetrical copper(II) dinuclear complex [Cu₂Cl₃(C₇H₆N₂)₅]Cl·4H₂O are reported. The crystals are orthorhombic, space group Pnma with 4 formula units in a cell of dimensions: a = 19.506(3), b = 17.384(4), C = 11.940(2) Å. The structure was solved by direct methods. Least-squares refinement using 2138 independent reflections with I3σ(I) has led to a final value of the conventional R factor (on F) of 0.047 and R_w of 0.049. The complex cation consists of pairs of deformed trigonal-bipyramidal copper(II) centers which share an edge by two equatorial chloride ions. The equatorial coordination sites of the Cu(1) atom are occupied by three chloride ligands, while of the Cu(2) atom by two chloride and one benzimidazole ligands. The axial sites are occupied by the nitrogen atoms from four benzimidazole ligands. The Cu atoms and equatorial ligands are located on the symmetry plane. The Cu---Cu non-bonding distance in the complex is 3.386(1) Å; the two shorter bridging Cu(1)---Cl(1) and Cu(2)---Cl(1) distances are 2.402(2) and 2.424(2) Å; the two longer Cu(1)---Cl(2) and Cu(2)---Cl(2) are 2.620(2) and 2.551(2) Å. The Cu(1)---Cl(1)---Cu(2) and Cu(1)---Cl(2)---Cu(2) angles are 89.1(1) and 81.8(1)°. The structure is the first example of a bibridged binuclear complex with two non-equivalent Cu---Cl---Cu bridges. Comparison to other binuclear bis(μ-halide)-bridged copper complexes of similar structure has been made. Magnetic susceptibility measurements indicate ferromagnetic coupling of the copper(II) centers, the intramolecular exchange parameter, 2J, being 5.6 cm⁻¹ and the intermolecular one J′ = −0.6 cm⁻¹. The investigation of the electronic structure of the complex and the orbital interpretation of the magnetic coupling based on extended Hückel molecular orbital calculations are also presented.     

Kinetics and mechanism of CO substitution of [η-CpFe(CO)3]PF6 with PPh3 in the presence of substituted pyridine N-oxide

The kinetics of substitution reactions of [η-CpFe(CO)₃]PF₆ with PPh₃ in the presence of R-PyOs have been studied. For all the R-PyOs (R = 4-OMe, 4-Me, 3,4-(CH)₄, 4-Ph, 3-Me, 2,3-(CH)₄, 2,6-Me₂, 2-Me), the reactions yeild the same product [η⁵-CpFe(CO)₂PPh₃]PF₆, according to a second-order rate law that is first order in concentrations of [η⁵-CpFe(CO)₃]PF₆ and of R-PyO but zero order in PPh₃ concentration. These results, along with the dependence of the reaction rate on the nature of R-PyO, are consistent with an associative mechanism. Activation parameters further support the bimmolecular nature of the reactions: ΔH^≠ = 13.4 ± 0.4 kcal mol⁻¹, ΔS^≠ = −19.1 ± 1.3 cal k⁻¹ mol⁻¹ for 4-PhPyO; ΔH^≠ = 12.3 ± 0.3 kcal mol⁻¹, ΔS^≠ = 24.7 ±1.0 cal K⁻¹ mol⁻¹ for 2-MePyO. For the various substituted pyridine N-oxides studied in this paper, the rates of reaction increase with the increasing electron-donating abilities of the substituents on the pyridine ring or N-oxide basicities, but decrease with increasing ¹⁷O chemical shifts of the N-oxides. Electronic and steric factors contributing to the reactivity of pyridine N-oxides have been quantitatively assessed.     

Anomalous carbonylation of [Pd(dppm)(O2CCF3)]2 to give an asymmetric μ-CO complex

The reactive palladium dimer, [Pd(dppm)(O₂CCF₃)]₂, is carbonylated to [Pd(dppm)(O₂CCF₃)]₂(μ-CO) in a reversible reaction with K = c. 7.2(2)x10⁴ atm⁻¹ (P_1/2 = c. 2.4 Torr). This is significantly larger than is expected based on the λ_max = 280 nm in the electronic spectrum. The product can be isolated in analytically pure form by crystallization under a CO atmosphere. It forms crystals in the monoclinic space group Cc with a = 18.584(5), b = 28.65(1), c = 11.164(3) Å and β = 95.16(2)°. The structure is significantly distorted. The bonding about the two palladium atoms is quite asymmetric. While one is close to a square planar geometry with a Pd---C(O) distance of 1.90(2) Å, the other is significantly pyramidalized and has a longer (2.00(2) Å) bond to the bridging CO. The Pd---Pd distance is only 2.896(2) Å, much shorter than that usually observed for formally non-bonded Pd atoms.     

Synthesis of 5,6-dihydro-4H-1,3-oxazines from neutral and cationic platinum(II) nitrile complexes. X-ray structure of trans-[Pt(CF3){ H2CH2}(PPh3)2]BF4

The 1,3-oxazine complexes cis- and trans-[PtCl₂{ C(R)OCH₂CH₂C}H₂₂] (cis: R=CH₃ (1a), CH₂CH₃ (2a), (CH3)₃C (3a), C₆H₅ (4a); trans:R =CH₃ (1b), C₆H₅ (4b)) were obtained in 51-71% yield by reaction in THF at 0 °C of the corresponding nitrile complexes cis- and trans-[PtCl2(NCR)₂] with 2 equiv. of ⁻OCH₂CH₂CH₂Cl, generated by deprotonation of 3-chloro-1-propanol with n-BuLi. The cationic nitrile complexes trans-[Pt(CF₃)(NCR)(PPh₃)₂]BF₄ (R=CH3, C₆H₅) react with 1 equiv, of ⁻ OCH2CH2CH2Cl to give a mixture of products, including the corresponding oxazine derivatives trans-[Pt(CF₃){ CH₂}(PPh₃)₂]BF₄ (5 and 6), the chloro complex _trans- [Pt(CF₃)Cl(PPh₃)₂] and free oxazine H2. For short reaction times (c. 5–15 min) the oxazine complexes 5 and 6 could be isolated in modest yield (37–49%) from the reaction mixtures and they could be separated from the corresponding chloro complex (yield 40%) by taking advantage of the higher solubility of the latter derivative in benzene. For longer reaction times (> 2 h), trans-[Pt(CF₃)Cl(PPh₃)₂] was the only isolated product. Complex 6 was crystallographically characterized and it was found to contain also crystals of trans- [PtCl{ H₂}(PPh₃)₂]BF₄, which prevented a more detailed analysis of the bond lengths and angles within the metal coordination sphere. The 1,3-oxazine ring, which shows an overall planar arrangement, is characterized by high thermal values of the carbon atoms of the methylene groups indicative of disordering in this part of the molecule in agreement with fast dynamic ring processes suggested on the basis of ¹H NMR spectra. It crystallizes in the trigonal space group P , with a=22.590(4), b=15.970(3) Å, γ=120°, V=7058(1) ų and Z=6. The structure was refined to R=0.059 for 3903 unique observed (I3σ(I)) reflections. A mechanism is proposed for the conversion of nitrile ligands to oxazines in Pt(II) complexes.     

Structure and properties of a novel OH bridged dimetal helical complex with 6,6-dimethyl-2,2′:6′,2″:6″,2:6,2-quinquepyridine ligand

A new monohelical OH⁻ bridged dinuclear complex [Zn₂(dmqpy)(OOCCH₃)₂(μ-OH)][ClO₄] · 0.5EtOH, where dmqpy is 6,6-dimethyl-2,2′:6′,2″:6″,2:6,2-quinquepyridine, has been synthesized and characterized by X-ray crystallography: monoclinic, space group P2₁/c, a=13.670(1), b=14.751(1), c=16.782(1) Å, β=96.59(1)°, U=3361.7(4) ų, Z=4, R=0.0601. Two Zn(II) ions are in different coordination modes, one is five-coordinate with a N₃O₂ donor set and the other is N₂O₂ four-coordinate with a distorted tetrahedral geometry, and the zinc ions are bridged by a hydroxyl group. The presence of the OH⁻ bridge is further confirmed by electrospray mass and infrared spectroscopies. The solution properties of the complex were investigated by ¹H NMR spectroscopy. The results of NMR indicate that the complex has higher symmetry in solution than in the solid state.     

Syntheses, structures and spectroscopy of new heteroselenometalates

[PPh₄]₂[MoSe₄] and [PPh₄]₂[WSe₄] react with two equivalents of AuCN in CH₃CN to afford [PPh₄]₂[(NC)Au(μ-Se)₂-Mo(μ-Se)₂Au(CN)] · CH₃CN (bd1) and [PPh₄]₂[(NC)Au(μ-Se)₂Au(CN)] · CH₃CN (bd2), respectively. Compounds 1 and 2 are isostructural. Compound 1 crystallizes in the triclinic space group with two formula units in a cell dimensions a=13.181(4), b=14.239(4), C=14.684(4) Å, α=73.00(3), β=73.66(2), γ=79.06(2)° at 113 K. Full anisotropic refinement of the structure of 1 on F² led to a value of R₁=0.0562 for those 9075 data having F_o² . 2σ(F_o²). The [(NC)Au(μ-Se)₂Mo(μ-Se)₂Au(CN)]²⁻ anion of 1 comprises two AuCN fragments ligating the opposite edges of a tetrahedral [MoSe₄]²⁻ moiety. Compounds 1 and 2 exhibit an IR band at 2250 cm⁻¹ that may be assigned to a CN stretching mode of the CH₃CH solvate; such a solvate molecule was found in the crystal structure of 1. The ⁷⁷Se NMR spectra show a resonance at 1104 ppm for 1 and 832 ppm for 2. Addition of excess PME₂Ph to the same solutions that produce 1 and 2 results in the formation of [PPh₄][(Me₂PhP)Au(μ-Se)₂MoSe₂] (3) and [PPh₄][(Me₂PhP)Au(μ-Se)₂WSe₂] (4), respectively. Compounds 3 and 4 are not isostructural. Compound 3 crystallizes in the monoclinic space gorup Cc with four formula units in a cell of dimensions a=21.912(4), B=9.809(2), C=15.959(3) Å, β=100.79(3) at 113 K. Full anisotropic refinement of the structure of 1 on F² led to a value of R₁=0.0481 for those 6851 data having F_o² > 2σ(F_o²). Compound 4 crystallizes in the triclinic space group with two formula units in a cell of dimensions a=11.315(2), B=13.053(3), C=14.173(3) Å, α=103.59(3), β=103.55(3), γ=114.75(3)δ at 113 K. Full anisotropic refinement of the structure of 4 on F² led to a value of R₁=0.0414 for those 7825 data having F_o² > 2σ(F_o²). The [(Me₂]PhP)Au(μ-Se)₂MoSe₂]⁻ anion of 3 and the [(Me₂PhP)Au(μ-Se)₂WSe₂]⁻ anion of 4 comprise an [(Me₂PhP)Au]⁺ fragment ligated across an edge of a tetrahedral (MSe₄]²⁻ moiety. [PPh₄]₂[MoSe₄] and [PPh₄]₂[WSe₄] react with one equivalent of AuCN in CH₃CH to afford [PPh₄]₂[(NC)Au(μ-Se)₂MoSe₂] (5) and [PPh₄]₂[(NC)Au(μ-Se)₂WSe₂] (6), respectively. Compounds 5 and 6 are isostructural. Compounds 5 crystallizes in the monoclinic space group C2/c with four formula units in a cell of dimensions a=11.234(15), B=20.329(28), C=20.046(28) Å, β=91.81(5)° at 113 K. Full anisotropic refinement of the structure of 5 on F² led to a value of R₁=0.0457 for those 4003 data having F_o² > 2σ(F_o²). The [(NC)Au(μ-Se)₂MoSe₂]²⁻ anion of 5, which has a crystallographically imposed twofold axis, comprises an AuCN fragment ligated across an edge of a tetrahedral [MoSe₄]²⁻ moiety. The reaction of [PPh₄]₂(NC)Cu(μ-Se)₂MoSe₂] with one equivalent of AuCN in CH₃CN produces a precipitate that is then redissolved through reaction with an excess of PMe₂Ph to afford [PPh₄][(Me₂PhP)₂Cu(μ-Se)₂MoSe₂] (7). Compound 7 crystallizes in the monoclonic space group P1₁/c with four formula units in a cell of dimensions a=9.975(1), B=30.391(7), C=14.541(6) Å, β=109.66(3) at 113 K. Full anisotropic refinement of the structure of 7 on F² led to a value of R₁=0.0305 for those 5205 data having F_o² > 2σ(F_o²). The [(Me₂PhP)₂Cu(μ-Se)₂MoSe₂]⁻ anion of 7 comprises an [(Me₂PhP)₂Cu]⁺ fragment ligated across an edge of the [MoSe₄]²⁻ moiety to provide a tetrahedral geometry about the Cu atom. The NMR, IR and UV-Vis spectroscopic data for these compounds are consistent with their solid-state structures.     

N7 and C8 coordinated purine complexes of [(NH3)5Os]. Crystal structures of 7-[9MeHyp(NH3)5Os]Cl3·H2O and 8-[1,3,7Me3Xan(NH3)5Os]Cl3·2H2O

Pentaammineosmium(III) coordinates to both the N7 and C8 positions of purine rings. The compound 7-[9MeHyp(NH₃)₅Os]Cl₃·H₂O crystallizes in the orthorhombic space group Pnma (No. 62) with the unit cell parameters: a=11.542(2), b=6.9841(8), c=21.960(3) Å and Z=4. The compound 8-[1,3,7Me₃Xan(NH₃)₅Os]Cl₃·2H₂O crystallizes in the monoclinic space group P2₁/c (No. 14) with the unit cell parameters: a=7.1228(X), b=14.613(1), c=19.667(1) Å, β=91.782(9)° and Z=4. The Os---C bond in the latter structure is 2.039(9) Å and the imidazolylidine ligand exerts a slight trans influence seen in the lengthening of the Os---N_ax distance (2.172(8) Å) by about 0.05 Å relative to the average of the equatorial Os---N_eq value of 2.123(8) Å. The spectroscopic, electrochemical and structural properties of these and additional N-bound purine complexes are compared with those of similar N7 and C8 ruthenium(III) species.     

trans-Bis[(thiocyanato-S)(1-methylimidazoline-2(3H)-thione)-μ2-(1-methylimidazoline-2(3H)-thione)copper(I)]: preparation, thermal analysis and crystal structure

1-Methylimidazoline-2(3H)-thione (mimtH) and copper(I) thiocyanate in refluxing ethanolacetonitrile produce a colourless, diamagnetic complex, [Cu₂(mimtH)₄(SCN)₂], which crystallises in an orthorhombic cell (a=8.0724(3), b=15.9545(6), c=21.3357(8) Å), space GROUP=Pbca, Z=4, final R=0.0319 from 2427 observed reflections F>4σ_c(F)). In the dimeric complex the copper(I) atoms are pseudo-tetrahedrally coordinated by pairs of, respectively, asymmetrically μ₂-S bridging mimtH, terminal monodentate-S mimtH, (Cu---S=2.290(1) Å), and terminal monodentate-S thiocyanate, (Cu---S=2.332(1) Å). Each pair of ligands is trans-related to its partner across crystallographic centres of symmetry, consequently, each copper(I) atom has an identical S₄ donor set with angles at the metal ranging from 95.9(1)° to 121.8(1)°. The centro-symmetric Cu₂S₂ core is rhomboid with Cu---S=2.377(1) and 2.457(1) Å, Cu---S_br---Cu=72.6(1)° and Cu---Cu, S_br---S_br separation distances of 2.861(1) and 3.897(2) Å, respectively. Thermal decomposition of the complex in flowing air, (133–1000 °C), involves de-sulfurisation of mimtH and thiocyanate with concomitant production of copper(II) sulfide followed by oxidation to copper(II) oxide.     

Molecular conformation of prostaglandin A1 monoclinic cyrstalline polymorph

The molecular conformation of the monoclinic crystalline polymorph of prostaglandin A₁ has been determined by X-ray diffraction techniques. The space group is P2₁ with a = 13.637 (2), b = 7.567 (1), I c = 10.576 (2) Å, β = 107.37 (3)°; D_c = 1.073 g·cm⁻³ for Z = 2. The molecular conformation is characterized by the nearly parallel arrangement of the C₁–C₇ and C₁₃–C₂₀ side chains, with a general flattening of the overall structure when compared with the orthorhombic polymorph. The cyclopentenone moiety assumes a C₈ envelope conformation with C₈ and O₉ displaced +0.29 Å and −0.18 Å from the C₉–C₁₀=C₁₁–C₁₂ plane respectively. Concerted, small variations of the torsion angles, primarily about the C₈–C₁₂, C₁₄–C₁₅ and C₁₆–C₁₇ bonds, bring the monoclinic and orthorhombic conformations into coincidence.     

X-ray crystal structures of the copper(II), nickel(II) and silver(I) complexes of a 17-membered dibenzo macrocycle with a N3S2 donor set

The copper(II), nickel(II) and silver(I) complexes of the pentadentate 17-membered macrocycle 1, 12, 15-triaza-3, 4:9, 10-dibenzo-5,8-dithiacycloheptadecane (L¹) have been prepared as perchlorates and characterized by X-ray crystallography. The N₃S₂ ligand uses all donor atoms for complexation. The copper coordination is square pyramidal with one sulfur atom in the axial site. Ni(II) displays an octahedral coordination by an interaction with a water molecule. The Ag(I) coordination is best described as a distorted pentagonal bipyramid. In [CuL¹]²⁺ the 1, 4, 7-triazaheptane fragment of L¹ is meridionally coordinated, but facially in [NiL¹(H₂O)]²⁺ and intermediate in [AgL¹](ClO₄). Crystal data for [CuL¹](ClO₄)₂: monoclinic, space group P2₁/n, a = 13.153(8), b = 11.951(5), c = 17.880(8)Å, β = 110.29(4)°, Z = 4, R = 0.086 for 2732 independent reflections with I 2σ(I); [NiL¹(H₂O)](ClO₄)₂: monoclinic, P2₁/a, a = 10.771(2), b= 16.157(2), c = 15.286(2) Å, β =93.08(1)°, Z = 4, R = 0.085 for 1464 independent reflections with I 2σ(I); [AgL¹](ClO₄): monoclinic, P2₁/n, a = 12.708(9), b = 9.483(7), c = 19.569(13) Å, β= 103.95(6)°, Z = 4, R = 0.039 for 3600 independent reflections with I 2σ(I).     

Synthesis of bent titanocene metalloligands with the (diphenylphosphino)tetramethylcyclopentadienyl moiety. X-ray structure of [(η-C5Me4 2)2TiCl2]Mo(CO)4

The reactions of lithium(diphenylphosphino)tetramethylcyclopentadienide with CpTiCl₃ and secondly with TiCl₃ followed by CCl₄ oxidation lead to the formation of two titanocene phosphines: (η⁵-C₅H₅)[η⁵-C₅Me₄P(C₆H₅)₂]TiCl₂ (2) and [η⁵-C₅Me₄P(C₆H₅)₂]₂TiCl₂ (3), respectively. The metalloligand 3 reacts readily with Mo(CO)₄cod, Mo(CO)₅THF and Mo(CO)₆ to give in each case [(η⁵-C₅Me₄ o(CO)₄ (6) as a sole product. The structure of 6 has been determined by X-ray diffraction. Crystal data: P , a = 11.716(1), b = 11.753(2), c = 16.110(2) Å, α = 99.06(1), β = 92.61(1), γ = 104.20(1)°, Z = 2. The molybdenum-titanium distance of 5.194(1) Å rules out any metal-metal interaction. The chlorine substitution reactions by CO in 2 and 3 and by thiolate group (pH₃C-C₆H₄-S) in 16 are reported.     

New Crystal Forms of the Motile Major Sperm Protein (MSP) ofAscaris suum

We have obtained two new crystal forms of theAscarismajor sperm protein (MSP) that mediates amoeboid cell motility in nematode sperm. We obtained crystals with C2 symmetry from bacterially expressed α-MSP witha= 216.5 Å,b= 38.6 Å,c= 32.5 Å, γ = 93.1° and also crystals with P2₁symmetry from native β-MSP witha= 63.1 Å,b= 91.7 Å,c= 72.5 Å, γ = 91.3°. A full native data set has been collected for each crystal form using synchrotron radiation. Both crystal forms diffract to 2 Å and are suitable for high-resolution structural investigation.     

The structures of bis(1H,5H-S-methylisothiocarbonohydrazidium) di-μ-chloro-octachlorodibismuthate(III) tetrahydrate and tris(1H-S-methylisothiocarbonohydrazidium) esachlorobismuthate(III)

The structures of bis(1H⁺,5H⁺-S-methylisothiocarbonohydrazidium) di-μ-chlorooctachlorodibismuthate(III) tetrahydrate: (C₂H₁₀N₄S)₂(Bi₂Cl₁₀)· 4H₂O (compound [I]) and of tris(1H⁺-S-methylisothiocarbonohydrazidium) esachlorobismuthate(III): (C₂H₉N₄S)₃(BiCl_5.67I_0.33) (compound [II]) were determined from single crystal X-ray diffractometer data. Both compounds crystallize as triclinic (P ); crystals [I] with Z = 1 formula unit in a cell of constants: A = 10.621(3), B = 9.989(5), C = 7.439(3) Å, α = 88.31(2), β = 84.51(2), γ = 68.88(2)°, final R = 0.0427 for 2229 unique reflections with I 2σ(I); crystals [II] with Z = 2 and cell dimensions: A = 14.109(4), B = 12.209(9), C = 8.206(7) Å, α = 103.54(3), β = 104.95(2), γ = 81.96(2)°, final R = 0.0411 for 3637 unique reflections (1 2σ(I)). The structure of [I] is built up of diprotonated organic cations, water molecules and dinuclear centrosymmetric [Bi₂Cl₁₀]⁴⁻ anions held together by N-HCl, N-HO, O-HCl hydrogen bonds and Van der Waals interactions. The [Bi₂Cl₁₀]⁴⁻ complex consists of two edge-sharing octahedra in which three pairs of bonds of similar length are observed (Bi-Cl_av = 2.602(5), 2.712(4), 2.855(5) Å). The structure of [II] consists of monoprotonated cations and [BiCl_5.67I_0.33]³⁻ anions held together by a tridimensional network of hydrogen bonds. Each bismuth atom is octahedrally surrounded by six chlorine atoms, one of which is statistically substituted by a iodine atom.     

Tetrachloroplatinate(II) and hexachloroplatinate(IV) salts of N,N,N′,N′-tetramethylethylenediammonium: significant differences in the conformation of the cation, as shown by infrared and x-ray diffraction data

The structures of (H₂tmen)[PtCl₄], (1), (H₂tmen = N,N,N′,N′-tetramethylethylenediammonium), [triclinic, P ; A = 7.344(3), B = 8.345(3), C = 6.216(2) Å, α = 84.53(3), β = 109.22(3), γ = 69.43(3)°, Z = 1] and (H₂tmen)[PtCl₆], (2), [monoclinic, P2₁/a; A = 14.409(4), B = 12.736(7), C = 8.601(3) Å, β = 99.58(3)°, Z = 4] were determined from diffractometric data by Patterson and Fourier methods and refined by full-matrix least-squares to R = 0.027 and 0.039 for (1) and (2) respectively. In both cases the anions and cations are joined in polymeric chains through hydrogen bonds involving the protonated nitrogens and the co-ordinated chlorine atoms. The square-planar [PtCl₄]²⁻ and octahedral [PtCl₆]²⁻ anions are centrosymmetric; the H₂tmen²⁺ cations are centrosymmetric in (1) with a N-C-C-N dihedral angle of exactly 180°, while in (2) the dihedral angle is 166°. The different symmetry of the organic moieties/C_i and C₁ in (1) and (2) respectively] results in a different i.r. spectrum which is more complex the lower the symmetry; moreover the spectrum of a KBr pellet of (2) changes with time, finally resembling that of (1) and of the (H₂tmen)Cl₂ salt.     

Molybdenum complexes with sterically-hindered thiolate ligands. The synthesis and structure of a seven coordinate complex with a molybdenum-diazenido core, [Mo(NNC6H5)(2-SC5H3N-3-SiMe3)3]

The reaction of [Mo₂Cl₄(μ-S₂)(μ-2-SC₅H₃NH-3-SiMe₃)(2-SC₅H₃N-3-SiMe₃)₂] with phenylhydrazine yields [Mo(NNPh)(2-SC₅H₃N-3-SiMe₃)₃] (1). Complex 1 adopts a pentagonal bipyramidal geometry with the phenyldiazenido group occupying an axial position. The structural parameters exhibited by 1 are similar to those of other members of the class of seven coordinate Mo-hydrazido and Mo-diazenido species. Crystal data for C₃₀H₄₁N₅Si₃S₃Mo (1): monoclinic space group P2₁n, a = 11.600(2), b = 14.880(3), c = 21.681(3) Å, β = 90.46(1)°, V = 3242.2(12) ų, Z = 4; 5690 reflections, R = 0.049.