Structural and theoretical studies of Xe(OChF5)2 and [XeOChF5][AsF6] (Ch = Se, Te)

The XeOSeF₅⁺ cation has been synthesized for the first time and characterized in solution by ¹⁹F, ⁷⁷Se and ¹²⁹Xe NMR spectroscopy and in the solid state by X-ray crystallography and Raman spectroscopy with AsF₆⁻ as its counter anion. The X-ray crystal structures of the tellurium analogue and of the Xe(OChF₅)₂ derivatives have also been determined: [XeOChF₅][AsF₆] crystallize in tetragonal systems, P4/n, a=6.1356(1) Å, c=13.8232(2) Å, V=520.383(14) Å³, Z=2 and R₁=0.0453 at −60°C (Te) and a=6.1195(7) Å, c=13.0315(2) Å, V=488.01(8) Å³, Z=2 and R₁=0.0730 at −113°C (Se); Xe(OTeF₅)₂ crystallizes in a monoclinic system, P2₁/c, a=10.289(2) Å, b=9.605(2) Å, c=10.478(2) Å, β=106.599(4)°, V=992.3(3) Å³, Z=4 and R₁=0.0680 at −127°C; Xe(OSeF₅)₂ crystallizes in a triclinic system, , a=8.3859(6) Å, c=12.0355(13) Å, V=732.98(11) Å³, Z=3 and R₁=0.0504 at −45°C. The energy minimized geometries and vibrational frequencies of the XeOChF₅⁺ cations and Xe(OChF₅)₂ were calculated using density functional theory, allowing for definitive assignments of their experimental vibrational spectra.     

Synthesis and crystal structure of two novel nickel (imidazole) complexes having hydrogen-bonded networks

Two nickel (imidazole) complexes, Ni(im)₆Cl₂·4H₂O (1) and Ni(im)₆(NO₃)₂ (2) (im=imidazole) have been synthesized and characterized by elemental analysis, IR, UV, TG and single crystal X-ray diffraction. 1 crystallizes in the triclinic space group P-1 with a=8.800(6) Å, b=9.081(6) Å, c=10.565(7) Å, =75.058(9)°, β=83.143(8)°, γ=61.722(8)°, V=718.3(8) Å³, Z=1 and R₁ (wR₂)=0.0469 (0.1497). 2 crystallizes in the trigonal space group R-3 with a=12.370(6) Å, b=12.370(6) Å, c=14.782(14) Å, =90.00°, β=90.00°, γ=120.00°, V=1959(2) Å³, Z=3 and R₁ (wR₂)=0.0358 (0.0955). 1 and 2 exhibit different supramolecular network due to their different counter anions and different hydrogen bonding connection. In compound 1, [Ni(im)₆]²⁺ cation and counter anions Cl⁻ alternatively array in an ABAB fashion via N–HCl hydrogen bonding. In compound 2, the plane of each NO₃²⁻ is almost parallel and each NO₃²⁻ connect three different [Ni(im)₆]²⁺ cations via N–HO hydrogen bonding.     

Novel coordination of a hydroxamic acid : Crystal structures of bis(glycinohydroxamoto)nickel(II) and tris(glycinohydroxamoto)cobalt(III)

The structures of two glycinohydroxamoto (GHA) complexes of Ni(II) and Co(III) have been determined by single-crystal X-ray diffraction methods. The crystals of Ni(GHA)₂ are monoclinic with a = 5.360(1), b = 7.315(4), c = 10.194(4) Å, β = 96.57(3), Z = 2, and space group P2₁/c. The crystals of Co(GHA)₃•1/2 H₂O are monoclinic with a = 22.467(19), b = 8.041(4), c = 13.700(11) Å, β = 116.01(7), Z = 8, and space group C2/c. The values of the final residuals R for Ni(GHA)₂ and Co(GHA)₃•1/2 H₂O are 0.0275 and 0.032, respectvely. The molecular structures of Ni(GHA)₂ and Co(GHA)₃ consist of a square planar and an octahedral coordination, respectively, with the glycinohydroxamato (NH₂CH₂CONOH⁻) ligands coordinating to the metal ion via the N (amino) and the N (NOH⁻). These two complexes are the first well-established cases of coordination of the NHO⁻ group of a hydroxamic acid to a transition metal via the nitrogen atom.     

Synthesis, crystal structure and third-order non-linear optical property of heterobimetallic cluster compound [MoOICu3S3(2,2′-bipy)2]

Nest-shaped cluster [MoOICu₃S₃(2,2′-bipy)₂] (1) was synthesized by the treatment of (NH₄)₂MoS₄, CuI, (n-Bu)₄NI, and 2,2′-bipyridine (2,2′-bipy) through a solid-state reaction. It crystallizes in monoclinic space group P2₁/n, a=9.591(2) Å, b=14.820(3) Å, c=17.951(4) Å, β=91.98(2)°, V=2549.9(10) ų, and Z=4. The nest-shaped cluster was obtained for the first time with a neutral skeleton containing 2,2′-bipy ligand. The non-linear optical (NLO) property of [MoOICu₃S₃(2,2′-bipy)₂] in DMF solution was measured by using a Z-scan technique with 15 ns and 532 nm laser pulses. The cluster has large third-order NLO absorption and the third-order NLO refraction, its ₂ and n₂ values were calculated as 6.2×10⁻¹⁰ and −3.8×10⁻¹⁷ m² W⁻¹ in a 3.7×10⁻⁴ M DMF solution.     

Structures of propionaldehyde, butyraldehyde, and pivalaldehyde complexes of the chiral rhenium fragment [(η-C5H5)Re(NO)(PPh3)]

The crystal structures of propionaldehyde complex (RS,SR)-(η⁵-C₅H₅)Re(NO)(PPh₃)(η²-O=CHCH₂CH₃)]⁺ PF₆⁻ (1b⁺ PF₆^s−; monoclinic, P2₁/c (No. 14), a = 10.166 (1) Å, b = 18.316(1) Å, c = 14.872(2) Å, β = 100.51(1)°, Z = 4) and butyraldehyde complex (RS,SR)-[(η⁵-C₅H₅)Re(NO)(PPh₃)(η²-O=CHCH₂CH₂CH₃)]⁺ PF₆⁻ (1c⁺PF₆⁻; monoclinic, P2₁/a (No. 14), a = 14.851(1) Å, b = 18.623(3) Å, c = 10.026(2) Å, β = 102.95(1)°, Z = 4) have been determined at 22°C and −125°C, respectively. These exhibit C O bond lengths (1.35(1), 1.338(5) Å) that are intermediate between those of propionaldehyde (1.209(4) Å) and 1-propanol (1.41 Å). Other geometric features are analyzed. Reaction of [(η⁵-C₅H₅)Re(NO)(PPh₃)(ClCH₂Cl)]⁺ BF₄⁻ and pivalaldehyde gives [(η⁵-C₅H₅)Re(NO)(PPh₃)(η²-O=CHC(CH₃)₃)]⁺BF₄⁻ (81%), the spectroscopic properties of which establish a π C O binding mode.     

Structural characterisation of [Pt(NH3)4]2[W(CN)8][NO3]·2H2O donor–acceptor complex

The bimetallic [Pt(NH₃)₄]₂[W(CN)₈][NO₃]·2H₂O is characterised by single-crystal X-ray diffraction [S.G.P2₁/m(11), a=8.0418(7), b=19.122(2), c=9.0812(6) Å, Z=2]. All platinum centres have the square-plane D_4h geometry with average dimensions Pt(1)–N 2.042(2) and Pt(2)–N 2.037(10) Å. The octacyanotungstate anion has the square-antiprismatic D_4d configuration with average dimensions W(1)–C 2.164(13), C–N 1.140(12), W(1)–N 3.303(5) Å. The structure exhibits two different mutual orientations of Pt versus W units resulting in Pt(2)–W(1), W(1)^* separations of 4.77(2), 4.55(2)^* and Pt(1)–W(1) of 6.331(8) Å. A centrosymmetric structure reveals groups of two distinct columns: the first is formed by intercalated NO₃⁻ between parallel [Pt(1)(NH₃)₄]²⁺ planes and the second consists of [W(CN)₈]³⁻ interlayered by, parallel to square faces of W-antiprisms, [Pt(2)(NH₃)₄]²⁺. The structure is stabilised through a three-dimensional hydrogen bond network via nitrogen atoms of cyanide ligands, hydrogen atoms of NH₃ ligands, water molecules and oxygen atoms of NO₃⁻ counteranions. The vibrational pattern and the range of ν(CN) frequencies attributable to the electronic environment of W(V) and W(IV) are consistent with the ground state Pt(II)↔W(V) charge transfer.     

Syntheses and structural determination of nine-coordinate K3[Nd(nta)2(H2O)]·6H2O and K3[Er(nta)2(H2O)]·5H2O

The syntheses and structural determination of Nd^III and Er^III complexes with nitrilotriacetic acid (nta) were reported in this paper. Their crystal and molecular structures and compositions were determined by single-crystal X-ray structure analyses and elemental analyses, respectively. The crystal of K₃[Nd^III(nta)₂(H₂O)]·6H₂O complex belongs to monoclinic crystal system and C2/c space group. The crystal data are as follows: a=1.5490(11) nm, b=1.3028(9) nm, c=2.6237(18) nm, β=96.803(10)°, V=5.257(6) nm³, Z=8, M=763.89, D_c=1.930 g cm⁻³, μ=2.535 mm⁻¹ and F(000)=3048. The final R₁ and wR₁ are 0.0390 and 0.0703 for 4501 (I>2σ(I)) unique reflections, R₂ and wR₂ are 0.0758 and 0.0783 for all 10474 reflections, respectively. The Nd^IIIN₂O₇ part in the [Nd^III(nta)₂(H₂O)]³⁻ complex anion has a pseudo-monocapped square antiprismatic nine-coordinate structure in which the eight coordinate atoms (two N and six O) are from the two nta ligands and a water molecule coordinate to the central Nd^III ion directly. The crystal of the K₃[Er^III(nta)₂(H₂O)]·5H₂O complex also belongs to monoclinic crystal system and C2/c space group. The crystal data are as follows: a=1.5343(5) nm, b=1.2880(4) nm, c=2.6154(8) nm, b=96.033(5)°, V=5.140(3) nm³, Z=8, M=768.89, D_c=1.987 g cm⁻³, μ=3.833 mm⁻¹ and F(000)=3032. The final R₁ and wR₁ are 0.0321 and 0.0671 for 4445 (I>2σ(I)) unique reflections, R₂ and wR₂ are 0.0432 and 0.0699 for all 10207 reflections, respectively. The Er^IIIN₂O₇ part in the [Er^III(nta)₂(H₂O)]³⁻ complex anion has the same structure as Nd^IIIN₂O₇ part in which the eight coordinate atoms (two N and six O) are from the two nta ligands and a water molecule coordinate to the central Nd^III ion directly.     

Oxygen abstraction from tetrahydrofuran by molybdenum-iodide complexes. X-ray molecular structure of [Mo2(μ-O)(μ-I)(μ-O2CCH3)I2(THF)4][MoOI4(THF)] (THF = tetrahydrofuran)

The interaction between Mo₂(O₂CCH₃)₄, Me₃SiI and I₂ in THF resulted in oxygen abstraction from the solvent and formation of [Mo₂(μ-O)(μ-I)(μ-O₂CCH₃) I₂(THF)₄]⁺[MoOI₄(THF)]⁻ and I---(CH₂)₄---I. The molybdenum complex has been characterized by X-ray diffractometry. Crystal data: triclinic, space group P , a = 13.827(3) Å; b = 15.803(7) Å; c = 9.950(3) Å; = 93.34(4)°; β = 102.40(2)°; γ = 90.09(2)°; V = 2120(2) Å₃; Z = 2; d_calc = 2.559 g cm⁻³; R = 0.0476 (R_w = 0.0613) for 370 parameters and 3938 data with F₀²> 3σ(F₀²). The metal-metal distance in the cation is 2.527(2) Å and indicates a strong interaction. The magnetic behavior is consistent with the assignment of one unpaired electron to the Mo₂⁷⁺ core of the cation and one to the d¹ Mo(V) center of the anion. The interaction between Mo(CO)₆ and I₂ in THF also results in the formation of 1,4-diiodobutane.     

A survey of the lone pair effect on the ring geometry of 1,2,4-triazoles and analogous 1,2,3-triazoles and imidazoles : The structures of 1-methyl-5-amino-3-methylthio-1,2,4-triazole, 1-phenyl-5-amino-3-methylthio-1,2,4-triazole and 1-(4-methylbenzyl)-3-amino-5-methylthio-1,2,4-triazole

The structures of the title compounds have been established by X-ray crystallography from diffractometer data. Crystals of the first (I), C₄H₈N₄S, are monoclinic, space group P2₁/c, with a = 8.166(2), b = 10.481(1), c = 8.585(1) Å, β = 109.33(2)°, Z = 4, D_c = 1.381 g cm⁻³. Crystals of the second (II), C₉H₁₀N₄S, are monoclinic, space group P2₁/c, with a = 11.850(4), b = 7.898(1), c = 23.981 (6) Å, β = 117.23(2)°, Z = 8, D_c = 1.373 g cm⁻³. Crystals of the third (III), C₁₁H₁₄N₄S₁ are also monoclinic, space group P2₁/c with a = 12.829(3), b = 8.348(1), c = 11.088(4) Å, β = 94.40(4)°, Z = 4, D_c = 1.314 g cm⁻³. The structures, determined by direct methods (I, III) and Patterson synthesis (II) were refined to R = 0.039 for 1070 reflections of I, R = 0.040 for 2792 reflections of II and R = 0.041 for 1900 reflections of III. The characteristic features of the planar five-membered rings are studied in comparison with the analogous 1,2,3-triazoles and imidazoles. It is shown that these planar rings exhibit only two patterns of the endocyclic bond angles induced dominantly by the number and relative position of the N-lone pairs. A similar effect of the double bonds (attached to C atoms) is also discussed.     

Anionic derivatives of pentafluoro-λ-sulfanyl (fluorosulfonyl) acetic acid esters

New ester salts [R₃NH]⁺[F₅SC(SO₂F)C(O)OR′]⁻ where RH, CH₃CH₂ and R′CH₃,(CH₃)₂CH have been prepared from corresponding esters and amines. The sodiumsalt Na[F₅SC(SO₂F)C(O)OCH(CH₃)₂] was used to prepare the following -substitutedderivatives: SF₅CX(SO₂F)C(O)OCH(CH₃)₂, XBr, Cl. The crystal structure of[(C₂H₅)₃NH]⁺[F₅SC(SO₂F)C(O)OCH₃]⁻ was determined and is monoclinic: P2₁/n;a=8.758(2) Å, b=9.645(2) Å and c=19.167(4) Å; β=97.92(3)°; V=1603.6 ų; Z=4.     

Large heteropolymetalate complexes formed from lanthanide (Y, Ce, Pr, Nd, Sm, Eu, Gd), nickel cations and cryptate [As4W40O140]: synthesis and structure characterization

A new family of heteropolytungstate complexes (NH₄)₂₁[Ln(H₂O)₅{Ni(H₂O)}₂As₄W₄₀O₁₄₀]·xH₂O(Ln=Y, Ce, Pr, Nd, Sm, Eu, Gd) were prepared by the reaction of Na₂₇[NaAs₄W₄₀O₁₄₀]·60H₂O with NiCl₂·6H₂O and Ln(NO₃)₃·xH₂O at pH≈4.5. The crystal structures of (NH₄)₂₁[Gd(H₂O)₅{Ni(H₂O)}₂As₄W₄₀O₁₄₀]·51H₂O was determined by X-ray diffraction analysis and element analysis. The compound crystallizes in the monoclinic space group P2₁/n with a=19.754(3), b=24.298(4), c=39.350(6) Å, β=100.612(3)°, V=18564(5) ų, Z=2, R1(wR₂)=0.0544(0.0691). The central site S1 and two opposite sites S2 of the big cyclic ligand [As₄W₄₀O₁₄₀]²⁸⁻ are occupied by one Ln³⁺and two Ni²⁺, respectively, each site supply four O_d coordinating to metal ion, another one water molecule and other five water molecules coordinate, respectively, to Ni²⁺and Ln³⁺. Polyanion [Ln(H₂O)₅{Ni(H₂O)}₂As₄W₄₀O₁₄₀]²¹⁻ has C_2v symmetry. IR and UV–vis spectra of [NaAs₄W₄₀O₁₄₀]²⁷⁻ of the title compounds are discussed.     

Synthesis and molecular structure of the optically active organoaluminium dimer (S)-(—)-(S)-(—)- [(C6H5)CH(CH3)NHA1(CH3)2]2

Reaction of the optically active primary amine (S)-(—)--methylbenzylamine with trimethylaluminium in heptane affords the crystalline organoaluminium dimer (S)-(—)-(S)-(—)-[(C₆H₅)CH(CH₃)NHA1(CH₃)₂]₂. Isolated as large, colourless, extremely air-sensitive prismatic crystals, the title compound crystallizes in the orthorhombic space group P2₁2₁2₁ with unit cell parameters a = 8.406(3), b = 15.505(4), c = 17.547(5) Å, V = 2287 ų and p = 1.03 g cm⁻³ for Z = 4. Least-squares refinement based on 1477 observed reflections converged at R = 0.056, R_w = 0.058. Methane was eliminated during the course of the reaction due to cleavage of A1---C and N---H bonds resulting in an asymmetric A1₂N₂ fragment at the core of the organoaluminium dimer. The mean A1---C bond distance in the dimethylaluminium units is 1.930(8), while the mean A1---N bond distance is 1.950(5) Å. Specific rotation ([]_D²⁵ in CH₂C1₂)of the dimer is determined to be - 20.6°.     

Coordination geometry of chromium(VI) species. The first example of cis-bridging chromate ions in helically structured catena(μ-CrO4-O,O′)[Ni(HIm)3H2O]

Nickel(II) chromate complex with imidazole (HIm) was isolated from the [Ni²⁺–HIm–CrO₄²⁻] system in various experimental conditions, i.e. reagent molar ratios and nickel(II) salts. The catena(μ-CrO₄-O,O′)[Ni(HIm)₃H₂O] (1) crystallizes in monoclinic crystal system—space group P2₁/n with cell parameters: a=11.784(2), b=8.899(2), c=13.934(3) (Å), β=95.19(3) (°). The unit cell contains two independent helixes, left- and right-handed, stabilized by intrahelical and interhelical hydrogen bonds (HB) and π–π interactions. The cis coordination of the CrO₄²⁻ anions and the HB systems appeared to be the main determinants of the helical architecture. To the best of our knowledge the cis-chromate coordination was observed for the first time. The cis coordination causes the distortion of the nickel octahedron, which was analysed by 4 K single crystal electronic spectra with D_4h symmetry approximation (gaussian resolution and crystal field parameters). This symmetry was also confirmed with the polarised electronic spectra. The magnetic properties of the complex suggest the occurrence of weak intrachain antiferromagnetic interactions between the magnetic Ni^II center. The computational DFT studies of complex 1 assuming three possible isomers mer[(HIm)₃]–cis[(CrO₄²⁻)₂], mer–trans and fac–cis suggested that the main contribution to the stability of 1 might have interhelical and intrahelical hydrogen bonds.     

Control of selected physical properties of MX solids: an experimental and theoretical investigation

A series of eight materials of stoichiometry [Pt(L-L)₂X₂][Pt(L-L)₂]Y₄ (X is Cl, Br; L-L is 1,2-diaminoethane (en) or 1,2-diaminocyclohexane (chxn); Y is ClO⁻₄, X⁻) were synthesized. Crystal structures were determined for the compounds [Pt(chxn)₂Cl₂][Pt(chxn)₂](ClO₄)₄ 1, [Pt(chxn)₂Br₂][Pt(chxn)₂](ClO₄)₄2, and [Pt(chxn)₂Br₂][Pt(chxn)₂]Br₄ 4. All three of these compounds crystallize in the orthorhombic space group I222. Compound 1 has a = 5.711(1) Å, b = 7.804(1) Å, c = 24.101(7) Å, Z = 1, d_x = 2.033 g cm⁻³. Compound 2 has a = 5.781(1) Å, b = 7.720(1) Å, c = 24.036(5) Å, Z = 1, d_x = 2.174 g cm⁻³. Compound 4 has a = 5.379(1) Å, b = 7.028(1) Å, c = 23.884(4) Å, Z = 1, d_x = 2.440 g cm⁻³. These solids contain pseudo one-dimensional chains with a charge-density-wave (CDW) ground state structure: X-Pt(IV)-X···Pt(II)···X. Single crystal resonance Raman experiments were performed on all compounds to measure the symmetric X---Pt---X stretching frequency v₁ and the band edge. It is shown that the optical and electronic properties and, therefore, the CDW strength of these one-dimensional materials may be systematically varied over a wide range by employing different combinations of L-L and Y; templates composed of hydrogen bonded networks of L-L and Y were found to control the metal-metal separation, thereby controlling the X---Pt(IV)---X…Pt(II)…X chain geometry. Relationships between the CDW strength, measured as the ratio of the short M(IV)---X distance to the long M(II)---X distance, the band gap energy v₁ and the Pt---Pt separation are developed. The reaction coordinate is found to be dominated by changes in the M---M and Pt(II)---X separations over most of the range studied, with contributions from changes in the Pt^IV---X bonds becoming important only at the smallest M---M separations. Direct evidence demonstrating that MX systems are true Peierls distorted systems is also presented. These results are consistent with modeling based on Peierls-Hubbard hamiltonians. This work explains the unusual pressure and temperature dependences that have been observed for the structures and optical properties of this class of materials and also provides a wealth of information to benchmark many-body theoretical calculations modeling electron-electron and electron-phonon interactions in one-dimensional materials.     

Dynamic behaviour and X-ray analysis of chiral η-allylpalladium complexes. II

The DANTE technique and NOESY two-dimensional method have been employed to observe the isomerization of the chiral cationic complex [Pd(η³-CH₂CMeCH₂(P-P′)]⁺ (1a), where P-P′ = the chiral chelating ligand (S)(N-diphenylphosphino)(2-diphenylphosphinoxymethyl)pyrrolidine. The rate constant was found to be 0.5 s⁻¹ in CHCl₃ at 295 K and 1.50 s⁻¹ in the presence of added free ligand. In the latter case the epimerization proceeds by a π-σ-π mechanism via the intermediacy of a primary η¹-allylpalladium complex. Although the intermediate was not detected, the NMR findings reveal that it has the allylic terminus η¹-bonded to palladium. The structure of 1a in its PF₆⁻ salt has been determined. The compound crystallizes in the orthorhombic space group P2₁2₁2₁ with a 10.029(4) b 19.203(8) c 36.115(6) Å, Z = 8, R = 0.0572 and R_w = 0.0712 for 3716 observed reflections with I > 3σ(I).     

Das Reaktionsverhalten von Cp2NbCl2 gegenüber WF6—Struktur von [Cp2NbCl2]4[WF6]2[WCl6]

The oxidation of Cp₂NbCl₂ with pure WF₆ in SO₂ solution yielded the cationic metallocene species [Cp₂NbCl₂]⁺[WF₆]⁻ essentially in quantitative yield. The same reaction carried out in the presence of either equimolar amounts or a two-fold excess of HCN led to the preparation of the new niobocenium salt [Cp₂NbCl₂]₄⁺[WF₆]²⁻ which was studied by single crystal X-ray diffraction. This compound represents the first example of a structurally characterized metallocene-WF₆⁻ complex, and crystallizes in the tetragonal system: space group, P4₁2₁2(No. 92), a = 11.083(8) Å, c = 48.285 (9) Å; Z = 8; R = 0.0759, R_W = 0.0841. ab]Die Oxidation von Cp₂NbCl₂ mit reinem WF₆ führt in SO₂-Lösung zur Synthese von [Cp₂NbCl₂ ]⁺[WF₆]⁻ in nahezu quantitativer Ausbeute. Die analoge Reaktion führt unter Anwesenheit der äquimolaren Menge oder eines zweifachen Überschusses an HCN zur Ausbildung des Niobocenium-Komplexsalzes [Cp₂NbCl₂]₄⁺ [WF₆]₂⁻[WCl₆]²⁻, von dem eine Röntgenstrukturanalyse angefertigt wurde. Diese Verbindung repräsentiert den ersten structurell charakterisierten Vertreter eines Metallocen-WF₆⁻-Komplexes und kristallisiert im tetragonalen System: Raumgruppe P4₁2₁2 (Nr. 92), a = 11.083(8) Å, c = 48.285(9) Å; Z = 8; R = 0.0759, R_W = 0.0841. kw]Niobium; X-ray diffraction; Oxidation; Metallocenes     

Structural and spectral studies of N-2-(pyridyl)-, N-2-(3-, 4-, 5-, and 6-picolyl)- and N-2-(4,6-lutidyl)-N′-2-thiomethoxyphenylthioureas

Structures of the following compounds have been obtained: N-(2-pyridyl)-N′-2-thiomethoxyphenylthiourea, PyTu2SMe, monoclinic, P2₁/c, a=11.905(3), b=4.7660(8), c=23,532(6) Å, β=95.993(8)°, V=1327.9(5) ų and Z=4; N-2-(3-picolyl)-N′-2-thiomethoxyphenyl-thiourea, 3PicTu2SeMe, monoclinic, C2/c, a=22.870(5), b=7.564(1), c=16.941(4) Å, β=98.300(6)°, V=2899.9(9) ų and Z=8; N-2-(4-picolyl)-N′-2-thiomethoxyphenylthiourea, 4PicTu2SMe, monoclinic P2₁/a, a=9.44(5), b=18.18(7), c=8.376(12) Å, β=91.62(5)°, V=1437(1) ų and Z=4; N-2-(5-picolyl)-N′-2-thiomethoxyphenylthiourea, 5PicTu2SMe, monoclinic, C2/c, a=21.807(2), b=7.5940(9), c=17.500(2) Å, β=93.267(6)°, V=2893.3(5) ų and Z=8; N-2-(6-picolyl)-N′-2-thiomethoxyphenylthiourea, 6PicTu2SMe, monoclinic, P2₁/c, a=8.499(4), b=7.819(2), c=22.291(8) Å, β=90.73(3)°, V=1481.2(9) ų and Z=4 and N-2-(4,6-lutidyl)-N′-2-thiomethoxyphenyl-thiourea, 4,6LutTu2SMe, monoclinic, P2₁/c, a=11.621(1), b=9.324(1), c=14.604(1) Å, β=96.378(4)°, V=1572.4(2) ų and Z=4. Comparisons with other N-2-pyridyl-N′-arylthioureas having substituents in the 2-position of the aryl ring are included.     

Syntheses and crystal structures of 1,2:5,6:9,10:13,14:17,18:21,22-hexabenzo-3,7,11,15,19,23-hexadehydro[24]annulene (HBC), 1,2:5,6:9,10:13,14-tetrabenzo-3,7,11,15-tetradehydro[16]annulene (QBC) and a tetracobalt complex of QBC. The first example of a transition metal complex of QBC

1,2:5,6:9,10:13,14-Tetrabenzo-3,7,11,15-tetradehydro[16]annulene, or tetrabenzocyclyne (QBC) and 1,2:5,6:9,10:13,14:17,18:21,22-hexabenzo-3,7,11,15,19,23-hexadehydro[24]annulene (HBC) have been structurally characterized by X-ray. crystallography. QBC crystallizes in two different space groups; P2₁/c with a = 10.652(3) Å, b = 10.624(2) Å, c = 19.549(4) Å, β = 93.83(2)°, V = 2207.4(8) ų, and Z = 4 and P4₁2₁2 with a = 9.330(1) Å, c = 25.497(8) Å, V = 2219.6(12) Å, and Z = 4. HBC crystallizes in monoclinic P2₁/n with a = 14.763(3) Å, b = 10.296(2) Å, c = 22.057(4) Å, β = 108.61(3), V = 3177.4(11) ų, T = 133 K, and Z = 4. Reaction of QBC with dicobaltoctacarbonyl has produced a tetracobalt complex which has been characterized by X-ray crystallography. This complex crystallizes in monoclinic P2₁/c with a = 14.699(3) Å, b = 17.188(3) Å, c = 17.254(3) Å, β = 112.63(3)°, V = 4023.5(13) ų, and Z = 4. Only two of the four C---C triple bonds of QBC bind to dicobalthexacarbonyl moieties even when excess dicobaltoctacarbonyl is used.     

Interaction of titanium and tin chlorides in tetrahydrofuran. The X-ray crystal structure of [trans-TiCl2(THF)4][SnCl5(THF)]

The direct reaction between [TiCl₄(THF)₂] and SnCl₂ in tetrahydrofuran (THF) yields the green paramagnetic salt [trans-TiCl₂(THF)₄][SnCl₅(THF)]. The same compound is also formed in the reaction between [TiCl₃(THF)₃] and SnCl₄ in THF. Crystals of the title compound are monoclinic with a = 8.442(4), b = 21.589(9), c = 9.262(5) Å, β = 107.91(5)°, Z = 2, space group P2₁/m. Both metal ions are in an octahedral environment. The titanium atom in the cation [TiCl₂(THF)₄]⁺ lies on the symmetry centre. The tin atom in [SnCl₅(THF)]⁻ is located on the mirror plane.     

Thiocyanato adducts of chromium(II) carboxylates and the molecular structure of tetraethyl-ammonium tetra-μ-propionatodiisothio-cyanatodichromate(II)

X-Ray crystallographic studies on [NEt₄]₂[Cr₂[(O₂CC₂H₅)₄(NCS)₂] show that the Cr–Cr separation (2.467Å) in the dinuclear anion is one of the longest known. The thiocyanato groups are N-bonded, and the results emphasize the known sensitivity of the quadruple Cr–Cr bond to the nature of the axial ligands. The compound crystallises in the tetragonal space group P4/mnc with two molecules per unit cell, the dimensions of which are a = b = 9.785(1), c = 21.186(2) Å. Magnetic investigations from room to liquid nitrogen temperature on the tetra-μ-propionato complex and on [NMe₄]₂ [Cr₂(O₂CCH₃)₄(NCS)₂] show that both complexes have been obtained free from paramagnetic chromium(III) impurities. Their weak paramagnetic susceptibilities (X_cr is approx. 200 x 10⁻⁶ cm³ mol⁻¹ at 295 K and 50 x 10⁻⁶cm³mol⁻¹ at 90 K) are inherent, and are ascribed to temperature independent paramagnetism at low temperature plus para-magnetism arising from slight population of the triplet state (2J 700 cm⁻¹, g = 2, N = 50 x 10⁻⁶cm³mol⁻¹) at higher temperatures.