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The nature of the supramolecular host–guest complex involving 4-pyrrolidinopyridine (BuPC4) and cucurbit[6]uril (Q[6]) has been investigated by NMR and UV spectroscopy, MALDI-TOF mass spectrometry, X-ray crystallography and isothermal titration calorimetry. The results revealed that the alkyl chain of the guest BuPC4 is located inside the cavity of the Q[6] host, whereas the other section of the BuPC4 guest remains outside of the portal. A novel supramolecular host–guest complex of 4-pyrrolidinopyridine derivative (BuPC4) with cucurbit[6]uril (Q[6]) has been investigated. The result revealed that the alkyl chain of the guest BuPC4 is located inside the cavity of the Q[6] host, whereas the other section of the guest BuPC4 remains outside of the portal.

Four new microporous lanthanide coordination polymers of general formula [Ln(C8H3NO6)(L)0.5(H2O)]·3H2O (Ln = Pr, Nd, Sm and Gd, and L = C8H4O4 or C8H4O4/C8H3NO6) were hydrothermally synthesized using in situ ligand synthesis. The complexes are isostructural featuring the NbO type framework, which is constructed from chains of edge-sharing {LnO9} polyhedra. The one-dimensional channel extending in the [1 0 0] direction with an aperture of approximately 4 × 8 A2 houses water of crystallization, which are ordered in edge-shared pentagons by hydrogen bonding interactions. Evidence for the significance of the hydrogen bonding interactions in stabilizing the framework is presented. Crystallographic disorder in the organic ligands, including rare substitutional disorder, is described. The complexes show type I gas sorption isotherms characteristic of microporosity, and are thermally stable up to approximately 400 °C. The solid state luminescence properties of these complexes are included.

Chromium(III) complexes of two ethyl­ene cross-bridged tetra­aza­macrocycles were prepared and structurally characterized in order to extend the coordination chemistry of this ligand type farther towards the early transition metals., The crystal structure of di­chlorido­(4,10-dimethyl-1,4,7,10-tetra­aza­bicyclo­[5.5.2]tetra­deca­ne)chromium(III) hexa­fluorido­phosphate, [CrCl2(C12H26N4)]PF6, (I), has monoclinic symmetry (space group P21/n) at 150 K. The structure of the related di­chlorido­(4,11-dimethyl-1,4,8,11-tetra­aza­bicyclo­[6.6.2]hexa­deca­ne)chromium(III) hexa­fluorido­phosphate, [CrCl2(C14H30N4)]PF6, (II), also displays monoclinic symmetry (space group P21/c) at 150 K. In each case, the CrIII ion is hexa­coordinate with two cis chloride ions and two non-adjacent N atoms bound cis equatorially and the other two non-adjacent N atoms bound trans axially in a cis-V conformation of the macrocycle. The extent of the distortion from the preferred octa­hedral coordination geometry of the CrIII ion is determined by the parent macrocycle ring size, with the larger cross-bridged cyclam ring in (II) better able to accommodate this preference and the smaller cross-bridged cyclen ring in (I) requiring more distortion away from octa­hedral geometry.

A new microwave-assisted hydrothermal synthesis of carbon monolith is reported in this work. The process uses microwave heating at 100 °C under acidic condition by employing a triblock copolymer F127 as the template, and resorcinol–formaldehyde as the carbon precursor. Scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen sorption measurements, transmission electron microscopy, X-ray studies and thermogravimetic analysis were used to characterize the synthesized material. The carbon monolith is crack-free, mesoporous and has a high surface area of 697 m2/g. The results demonstrate that the microwave-assisted hydrothermal synthesis is a fast and simple approach to obtain carbon monoliths, as it reduces effectively the synthesis time from hours to a few minutes which could be an advantage in the large scale production of the material.

The ionothermal synthesis of two intercalated two-dimensional zinc benzenedicarboxylates, EMIm2[Zn3(C6H4(COO)2)3Cl2] (I) and BMIm2[Zn3(C6H4(COO)2)3Cl2] (II), employing the ionic liquids 1-ethyl-3-methylimidazolium chloride (EMIm-Cl) and 1-butyl-3-methylimidazolium chloride (BMIm-Cl) as solvents, is reported. Detailed characterization by X-ray diffraction, elemental analyses, vibrational and optical spectroscopies, and thermogravimetric analysis is described. The two compounds display an anionic two-dimensional structure with the composition [Zn3(C6H4(COO)2)3Cl2]2− which is intercalated and charge neutralized by the imidazolium cations. The compounds are remarkably stable: neither begins to lose mass until they are heated above 300 °C, above which temperature ZnO is obtained. The structural transformation of the anionic layered compounds I and II to a neutral one-dimensional structure with the composition Zn(C6H4(COO)2)(H2O)2 is described. The derived neutral compound shows better thermal robustness. Both the parent and the transformed structures display blue luminescence, arising from ligand centered π → π∗ and n → π∗ transitions.

Reaction of Me3Al (two equivalents) with ortho-, meta- or para-anisidine, (OMe)(NH2)C6H4, affords the complexes {[1,2-(OMe),NC6H4(μ-Me2Al)](μ-Me2Al)}2 (1), [1,3-(Me3AlOMe),NHC6H4(μ-Me2Al)]2 (2) or [1,4-(Me3AlOMe),NHC6H4(μ-Me2Al)]2 (3), respectively. The molecular structures of 1–3 have been determined and all three complexes were found to be highly active for the ring opening polymerization (ROP) of e-caprolactone. 1 was found highly active either with or without benzyl alcohol present; at various temperatures, the activity order 1 > 2 ≈ 3 was observed. For the ROP of rac-lactide results for 1–3 were poor.

The chemistry of N-organosilylalkyl-substituted heterocyclic bases (thymine, adenine and cytosine) is described, covering the structures of model compounds, the synthesis of substituted oligo-siloxanes and a preliminary report of the synthesis of a poly(organosiloxane) with pendant N-alkyl(heterocycle) functionalities. N-Alkenylthymines CH2[double bond, length as m-dash]CH(CH2)nT (T = thymine, n = 1 (1), 2 (2), 3 (3)) have been prepared and 2 hydrosilylated to form PhMe2Si(CH2)4T (5). Alternatively, 5 was prepared by reaction of PhMe2Si(CH2)4Br (6) with (O,O-SiMe3)2T, a method which has also been used to prepare PhMe2Si(CH2)4A (7) and PhMe2Si(CH2)4C (8) (A = adenine, C = cytosine). Model di- and tri-siloxanes [Br(CH2)4(Me)2Si]2O (10), Me3SiOSi(Me)2(CH2)4Br (11), PhMe2SiOSi(Me)2(CH2)4Br (12) and (Me3SiO)2(Me)Si(CH2)4Br (13) have been prepared by hydrosilylation of H2C[double bond, length as m-dash]C(H)(CH2)4Br with an appropriate hydrosiloxane and used to prepare Me3SiO(Me)2Si(CH2)4T (14), Me3SiO(Me)2Si(CH2)4A (15) (both from 11), and (Me3SiO)2(Me)Si(CH2)4T (16), (Me3SiO)2(Me)Si(CH2)4A (17) (both from 13). 10 reacts with thymine to give a mixture of the pyrimidocyclophane cyclo-T-N,N-[(CH2)4(Me)2Si]2O (19) and [T(CH2)4Si(Me)2]2O (20), while cytosine reacts similarly to form cyclo-C-N,N-[(CH2)4(Me)2Si]2O (21; as an imine) and [C(CH2)4Si(Me)2]2O (22); adenine only generates [A(CH2)4Si(Me)2]2O (18) in an analogous synthesis. Using a related protocol, polymeric {[MeSi(O)(CH2)4Br]2[Me2SiO]98}n (23) has been converted to {[MeSi(O)(CH2)4T]2[Me2SiO]98}n (24) and {[MeSi(O)(CH2)4A]2[Me2SiO]98}n (25). The structures of 4, 5, 8, 19 and 21, along with a 2 : 1 adduct of 5 with Ni(dithiobiuret)2 (9) are reported.

The authors wish to make the following correction to their paper [...]

Crystals of bis(guaninium) sulfate hydrate ((GH)2SO4. 2.5H2O) have been isolated via slow solvent evaporation. This compound adopts the triclinic space group P 1 ¯ with unit cell parameters a = 9.6300(19) A, b = 9.8613(19) A, c = 10.5872(19) A, α = 78.627(15)°, β = 71.518(15)°, γ = 63.260(14)° and unit cell volume 849.8(3) A3 at 150 K. The crystal structure displays intricate hydrogen bonding interactions between the guaninium cations, the sulfate anions and water. Guaninium cations are held together in approximately planar ribbons by hydrogen bonds. These ribbons are stacked parallel to the [230] direction and held together by hydrogen bonding to sulfate and water. Channels are formed between the hydrogen-bonded cations and the anions that are filled with water molecules. Remarkably, partial and complete removal of water from this structure is possible without wholescale loss of crystallinity. Partial removal of water to yield (GH)2 SO4. 1.5H2O happens with very limited change to the structure. It is possible to remove all of the water to yield the apohost, G(GH)3(SO4H)SO4 which retains many structural features of the hydrate but contains a different hydrogen bonding chain. The three structures and the relationship between them are described.

The main goal of solid-state chemistry is the synthesis and characterisation of new compounds with technologically exploitable properties. To this aim, one established chemical route is the modification of known inorganic materials, in most cases oxides, via substitution or insertion of cations different from the original makeup. An alternative, and less frequently adopted, approach is the manipulation of the anion sublattice to yield mixed-anion materials. Recent examples of materials with structural and physical properties tunable via both anionic and cationic substitutions are bringing more attention to the potential of this approach as an alternative and/or complementary chemical approach to cationic modifications. Within this review, structural relationships and differences between nitrides and mixed-anion nitrides, such as nitride-halides, nitride-sulfides, nitride-carbides and nitride-borides will be highlighted to set the scenery and the future challenges to a fuller exploitation of the ‘anionic route’ as a strategy towards the design of new materials.

A new flexible triazine-based polycarboxylate metal–organic framework, [Sm2(TTHA)(H2O)4]·9H2O (I) (TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetate), has been synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction, elemental analysis and FT-IR spectroscopy. Crystal data for I are monoclinic C2/c, a = 12.6974(13) A, b = 16.7309(12) A, c = 14.8076(15) A, β = 91.452(8)°, V = 3,144.7(5) A3. Each SmIII ion is 9-coordinate in a distorted tri-capped trigonal prismatic geometry; but, the principal inorganic building block is {Sm2O16}, which comprises two of these polyhedra that share an edge. The complex exhibits a three-dimensional open-framework structure of approximately 31 % void volume, which comprises two types of channels oriented in three directions; [0 0 1], [1 1 0] and [−1 1 0]. The network can be simplified into either the cooperite (pts) or anatase (ant) topologies depending on the choice of nodes. The UV–Vis spectra of the compound are dominated by the absorption of the TTHA ligand. Thermogravimetric analysis shows that the loss of channel and coordinated water upon heating occurs in two distinct steps.

The isostructural coordination polymers, M(isonicotinate)(tyrosinate)(H2O)2 [M = Co or Ni] have been synthesized by microwave-assisted hydrothermal methods. These compounds crystallize in the non-centric space group P21. At 290 K, for the cobalt analogue the unit cell parameters are a = 6.0658(6), b = 15.540(2), c = 9.1328(9) A, β = 107.052(7)°, V = 823.05(16) A3; for the nickel compound a = 6.0946(8), b = 15.443(2), c = 9.1202(11) A, β = 107.803(10)°, V = 817.28(19) A3. The structure contains linear chains with composition [M(isonicotinate)]∞ in which the isonicotinate is arranged head-to-tail and binds to octahedral cations through both pyridine and monodentate carboxylate functions. At each metal centre the coordination is completed by two cis water molecules and tyrosinate that chelates to the metal centre through monodentate carboxylate and amine groups. The chains run parallel to the crystallographic [101] direction. Between the chains there is extensive hydrogen bonding between bound water and carboxylate groups. The cobalt compound loses water upon heating above room temperature and continues to lose mass in ill-defined steps upon further heating; in contrast the nickel compound loses mass in well-defined steps. An achiral one dimensional chain can be decorated with the chiral auxiliary tyrosine to produce a homochiral coordination polymer.

The molecular structures of a number of solvates of the [2 + 2] Schiff-base macrocycles {[2-(OH)-5-(R)-C6H2-1,3-(CH)2][O(2-C6H4N)2]}2 (R = Me L(1)H2, tBu L(2)H2, Cl L(3)H2), formed by reacting 2,6-dicarboxy-4-R-phenol with 2,2'-oxydianiline (2-aminophenylether), (2-NH2C6H4)2O, have been determined. Reaction of L(n)H2 with two equivalents of AlR'3 (R' = Me, Et) afforded dinuclear alkylaluminium complexes [(AlR'2)2L(1-3)] (R = R' = Me (1), R = tBu, R' = Me (2), R = Cl, R' = Me (3), R = Me, R' = Et (4), R = tBu, R' = Et (5), R = Cl, R' = Et (6)). For comparative studies, reactions of two equivalents of AlR'3 (R' = Me, Et) with the macrocycle derived from 2,2'-ethylenedianiline and 2,6-dicarboxy-R-phenols (R = Me L(4)H2, tBu L(5)H2) were conducted; the complexes [(AlMe)(AlMe2)L(5)]·2¼MeCN (7·2¼MeCN) and [(AlEt2)2L(4)] (8) were isolated. Use of limited AlEt3 with L(3)H2 or L(5)H2 afforded mononuclear bis(macrocyclic) complexes [Al(L(3))(L(3)H)]·4toluene (9·4toluene) and [Al(L(5))(L(5)H)]·5MeCN (10·5MeCN), respectively. Use of four equivalents of AlR'3 led to transfer of alkyl groups and isolation of the complexes [(AlR'2)4L(1'-3')] (R = L(2'), R' = Me (11); L(3'), R' = Me (12); L(1'), R' = Et (13); L(2'), R' = Et (14); L(3'), R' = Et (15)), where L(1'-3') is the macrocycle resulting from double alkyl transfer to imine, namely {[2-(O)-5-(R)C6H2-1-(CH)-3-C(R')H][(O)(2-(N)-2'-C6H4N)2]}2. Molecular structures of complexes 7·2¼MeCN, 8, 9·4toluene, 10·5MeCN and 11·1¾toluene·1¼hexane are reported. These complexes act as catalysts for the ring opening polymerisation (ROP) of ε-caprolactone and rac-lactide; high conversions were achieved over 30 min at 80 °C for ε-caprolactone, and 110 °C over 12 h for rac-lactide.

The design of a melt synthesis of the first air-stable formulation of the metastable form III of paracetamol is derived from thermo-spectroscopic and thermo-diffraction experiments. Melt crystallisation in the presence of β-1,4-saccharides produces form III selectively and the excipients appear to act as stabilising 'active' templates of the metastable polymorph.

The crystal structures of Sr2CaMoO6 and Sr2CaTeO6 have been determined at room temperature by neutron powder diffraction. Both compounds crystallize in the perovskite structure with a rock-salt ordered array of Ca2+ and M6+ cations (M=Mo, Te) on the six-coordinate sites (space group P21/n (no. 14); for M=Mo, a = 5.76228 ( 7 ) , b = 5.84790 ( 7 ) , c = 8.18707 ( 9 ) A , β = 90.194 ( 1 ) ° , for M=Te, a = 5.79919 ( 9 ) , b = 5.83756 ( 8 ) , c = 8.2175 ( 1 ) A , β = 90.194 ( 1 ) ° ). Compositions in the solid solution Sr2CaMo1−xTexO6 have been synthesized and shown by X-ray diffraction to adopt the same ordered structure. The results are used in a discussion of the cation oxidation states in Ca2FeMoO6 and to establish the similarity between the structural chemistry of hexavalent Mo and Te.

A stereocontrolled synthesis of the core of eunicellin is described featuring a Claisen rearrangement and a diastereoselective organocatalytic Diels-Alder reaction as the key steps.

The first example of ferromagnetism in a compound crystallizing with the filled beta-manganese structure is reported. Magnetometry and neutron diffraction show that Fe1.5Pd0.5Mo3N is ferromagnetic below 160 K, with a saturation magnetization of 2.44 μB/formula unit which is associated with the Fe/Pd sublattice. Self-consistent spin-polarized electronic structure calculations, performed within density functional theory, predict an average magnetic moment of 2.93 μB/formula unit at T = 0 K. The moment is shown to be a result of the fulfilment of a local Stoner criterion on the Fe sites.

The introduction of group 10 metals into the hypothetical composition Fe2Mo3N allows the isolation of the solid solutions Fe2-xMxMo3N (M = Ni, Pd, Pt), which crystallize with the filled β-manganese structure (space group P4132, a ≈ 6.7 Å). These materials display ferromagnetism with the Curie temperature and saturation magnetization being dependent on the iron content; Fe1.25Mo0.75Mo3N shows the highest ordering temperature in each series (maximized at Tc = 225 K for M = Pt) and the highest magnetization is always observed for x = 0.5 (maximized at 2.44 μB per formula unit for M = Pd). © 2005 American Chemical Society.

Compositions in the solid solution Fe2-xRhxMo 3N which adopt the filled β-manganese structure have been prepared by the reductive nitridation of mixed binary metal oxides; single-phase samples can be prepared for 0.3 ≤ x ≤ 0.75. Those compositions with x ≤ 1 have been shown, by a combination of magnetometry, neutron diffraction and μSR, to be ferromagnetic at low temperatures. The Curie temperature is highest (Tc = 110 K) for x = 0.5, with a saturation magnetisation of 2.26(1) μB per formula unit. These compositions display metallic behaviour, with a change in the temperature gradient of the resistivity being observed at the Curie temperature. Fe0.5Rh1.5Mo 3N is also metallic but does not show long-range magnetic order. © The Royal Society of Chemistry 2005.

Compositions in the series Ni(2-x)Co(x)GeMo(3)N (0 < or = x < or = 2), Co(2)Ge(1-x)Ga(x)Mo(3)N (0 < x < or = 0.7), Co(2-x)Fe(x)GeMo(3)N (0 < or = x < or = 2), and Co(2-x)Fe(x)Ge(0.5)Ga(0.5)Mo(3)N (0 < or = x < or = 0.8) have been synthesized by the reductive nitridation of binary oxides and studied by appropriate combinations of magnetometry, transport measurements, neutron diffraction, and Mossbauer spectroscopy. All of these compositions adopt the cubic eta-carbide structure (a approximately 11.11 A) and show a resistivity of approximately 10(-3) Omega cm. No long-range magnetic order was observed in Ni(2-x)Co(x)GeMo(3)N, although evidence of spin freezing was observed in Co(2)GeMo(3)N. The introduction of gallium into this composition leads to the onset of antiferromagnetic ordering at 90 K in Co(2)Ge(0.3)Ga(0.7)Mo(3)N. The magnetic structure consists of an antiferromagnetic arrangement of ferromagnetic Co(4) groups, with an ordered magnetic moment of 0.48(9) micro(B) per cobalt atom. The same magnetic structure is found in Co(0.5)Fe(1.5)GeMo(3)N and Co(1.2)Fe(0.8)Ge(0.5)Ga(0.5)Mo(3)N. The former orders above room temperature with an average moment of 1.08(3) mu(B) per transition-metal site, and the latter at 228 K with an average moment of 1.17(4) micro(B) per site. The magnetic behavior of these compounds is discussed in terms of the electron count within each series.

The structure of the monohydrate of 5,5′-dithiobis(2-nitrobenzoic acid) has been redetermined and is reported in full. The compound crystallises in the centrosymmetric space group Pccn with unit cell parameters a = 11.3441(12), b = 13.7986(10), and c = 10.2422(7) A, V = 1603.2 (2) A3. The structure was determined at 120 K and the location of hydrogen atoms identified by difference Fourier methods. The 5,5′-dithiobis(2-nitrobenzoic acid) molecules are arranged in sheets sustained by hydrogen bonds to water. Pairs of carboxylic acid groups are bridged by hydrogen bonds to two molecules of water in a rare embrace with graph set notation C 4 3 (12). Between the sheets there are other S···π and C–H···O interactions. The solid state voltammetry and thermogravimetry of the compound are also reported. We report the crystal structure of the monohydrate of 5,5′-dithiobis(2-nitrobenzoic acid) (Ellman’s reagent), which displays unusual hydrogen bonding between carboxylic acid groups and water.

An efficient route is described to an unusual exocyclic 4-β-d-ribofuranosyl-aminoimidazole nucleoside, related 4-N-benzylaminoimidazoles and imidazole analogues of precursors in the de novo biosynthesis of purines, via a regiospecific and stereoselective base-catalysed Dimroth-type rearrangement of 1-ribofuranosyl and 1-benzyl-5-aminoimidazoles. Use of a 15N labelled precursor showed the unequivocal endo- to exocyclic translocation of the nitrogen atom during the rearrangement.

The molecular structure of a second form of [Ni(2,2′-bipyridine)(H 2 O) 3 (NO 3 )](NO 3 ) is reported. The previous report is for a blue monoclinic polymorph. The second form is orthorhombic and crystallises as green blocks with unit cell parameters a = 9.1201(12) A, b = 14.444(2) A, c = 21.805(4) A, V = 2872.4(8) A 3 , Z = 8. The complex was characterised by elemental analysis, infrared spectroscopy, UV–Vis spectroscopy, and thermogravimetry. The bipyridine acts as a bidentate ligand to Ni 2+ and the octahedral coordination is completed by three water molecules and one monodentate nitrate ion. A second nitrate forms hydrogen bonds to the bound water molecules. The difference between the two forms in terms of the molecular geometry is described in relation to other similar compounds. The key difference between the two forms is the orientation of the two nitrate anions, and hence the hydrogen bonding present.

Glyoxal-bridged bisaminal tetraazamacrocyclic derivatives of 1,4,7,10-tetraazacyclododecane (cyclen) and 1,4,8,11-tetraazacyclotetradecane (cyclam) can be N-functionalized to incorporate coordinating groups or for conjugation to biomolecules. Herein, we present an improved N-functionalization methodology using mechanochemistry which reduces reaction times in comparison with conventional synthetic routes. A range of six alkyl halides were reacted with cyclen and cyclam bisaminal derivatives in various ratios to form mono- and bis-functionalized quaternary ammonium salts. Cross-bridged cyclam, a key intermediate for CB-TE2A, a commonly used chelator in positron emission tomography medical imaging with (64)Cu, has been synthesized using nonconventional synthetic methodologies (grinding and microwave heating) with intermediates characterized by 2D NMR and single crystal XRD. The overall synthesis time of CB-TE2A from cyclam could be shortened to 5 days from the 35 days required for the conventional synthesis.

The low temperature crystal structure of the complex, Cr(urea)4(H2O)2·3NO3 (1), displays intriguing pseudosymmetry that complicates the structure determination. 1 crystallises in the centrosymmetric monoclinic space group P21/c with Z = 8 and Z′ = 2; a = 18.3338(4) A, b = 16.5472(4) A, c = 13.9252(3) A and β = 106.3260(10)°, V = 4054.19(16) A3. The two symmetry independent [Cr(urea)4(H2O)2]3+ ions in the asymmetric unit both feature coordinated urea (O=C(NH2)2) and lie on general positions. A further six independent nitrate anions complete the structure. The unit cell is primitive but the two Cr3+ ions are related by a pseudo translation of ½, ½, 0. The deviation from a truly C-centred cell is clear from an examination of geometry of the urea ligands and the hydrogen bonds which they form. The identification of the space group in this case is described and methods for quantifying the degree of deviation from a C-centred cell discussed. Cr(urea)4(H2O)2·3NO3 adopts a primitive unit cell with Z′ = 2 and is pseudo C-centred; small differences in the orientations of the ligands are responsible for the removal of the C-centring.

Two extended solids displaying both one-dimensional coordination polymer and two-dimensional hydrogen-bonded structural features has been prepared under microwave-assisted hydrothermal conditions. [Co(H2O)4(4,4′-bipyridine)](4,4′-bipyridineH2)·2(SO4)·2H2O (1) contains one-dimensional coordination polymer chains of composition [Co(4,4′-bipyridine)(H2O)42+]n that are linked into a three dimensional framework by hydrogen bonding through uncoordinated sulfate and water. Within this framework is located a twice protonated 4,4′-bipyridine molecule (C10N2H102+) which forms two short N–H ⋯ O hydrogen bonds and eight further non-classical C–H ⋯ O interactions. The close approach of guest and framework and the large number of interactions between them suggest the cation is important in templating this phase. [Co2(4,4′-bipyridine)2(SO4)2(H2O)6]·4(H2O) (2) displays one dimensional chains of cobalt-bipyridine which are sinusoidal in nature. Two sets of these chains run parallel to the crystallographic [2 1 2] and [ 2 ¯ 1 2 ¯ ] directions. Two-dimensional hydrogen-bonded sheets parallel to the xz plane link these; further hydrogen bonds to uncoordinated water help to form a three-dimensional honeycomb network with the centroids of the six-membered rings aligned parallel to the a-axis. The use of microwave synthesis for framework solids of this type is described and the structures of the frameworks and the interactions responsible for their assembly are discussed. The thermal and spectroscopic behaviour of the two phases are described.

A new low temperature synthetic route to binary and ternary metal antimonides is reported. Binary transition metal antimonides prepared include CoSb3, CoSb2, CoSb, NiSb, NiSb2, Cu2Sb and Mo3Sb7; new ternary compositions prepared include the series Co1−xNixSb (0.1 ≤ x ≤ 0.9). The intermetallic SnSb has also been prepared by this route. The synthetic method is simple and does not require the use of very high temperatures, multi-step reactions or reaction under vacuum. Compounds were synthesised by the reduction of mixed metal oxides under 10% hydrogen in argon at moderate temperatures (approx. 450 °C). The route affords some control over the stoichiometry of the product. High purity binary phases formed include CoSb3, CoSb, NiSb, Cu2Sb and SnSb. Owing to the significantly different reduction temperatures of the starting metal oxides, Mo3Sb7 was formed with impurities of MoO2 and Sb metal. CoSb2 and NiSb2 were formed with impurities of CoSb3 and NiSb, respectively.

In situ energy-dispersive X-ray diffraction has been used to investigate the synthesis of the recently reported lanthanide hydroxynitrate phases, Ln2(OH)5NO3·1.5H2O (Ln = Y, Er, Yb). Through control of the reaction temperature, three distinct layered phases with differing degrees of hydration (x = 1 (1), 1.5 (2), and 2 (3)) were observed in the Yb synthesis and subsequently isolated. Only the phase with x = 1.5 was observed for the reactions with Y and Er. The crystal structures of Yb2(OH)5NO3·2H2O (2) and Yb2(OH)5NO3·H2O (3) were determined in a single-crystal diffraction study and represent the first crystal structures of the new lanthanide hydroxynitrate phases. Both Yb2(OH)5NO3·2H2O and Yb2(OH)5NO3·H2O adopt orthorhombic structures in which the nitrate anion is coordinated to the Yb3+ cations within the hydroxide layer and are largely resistant to anion exchange. This is in contrast to the Ln2(OH)5NO3·1.5H2O phases, which undergo facile anion exchange reactions at room temperature, indicating that the...

The structure of 2,3,4-trihydroxybenzoic acid dihydrate has been determined at 120 K from a twinned crystal. The compound crystallizes in the centrosymmetric space group $$ \text{P}\bar{1} $$ with Z = 2 and unit cell parameters a = 6.6165(14), b = 7.2341(14), c = 9.716(2) A, α = 75.632(16), β = 76.818(17), γ = 77.520(16)°. There is extensive hydrogen bonding within the structure and evidence for intermolecular π–π interactions between parallel aromatic rings. The compound does not display the familiar carboxylic acid hydrogen-bonded dimer found in many similar compounds. The 2,3,4-trihydroxybenzoic acid molecules are however arranged in a head-to-tail chain and linked through two water molecules in an unusual intermolecular hydrogen bonding motif. The crystal structure of naturally occurring phenolic antioxidant 2,3,4-trihydroxybenzoic acid dihydrate was determined at 120 K from a twinned crystal.

Treatment of the 16-electron hydroxy hydride complex [Ru(IMes)(2)(CO)H(OH)] (1, IMes = 1,3-bis-(2,4,6-trimethylphenyl)imidazol-2-ylidene) with HC CR affords the alkynyl species [Ru(IMes)(2)(CO) H(C CR)] (R = Ph 3, SiMe3, 4) and [Ru(IMes)(2)(CO)(C CR)(2)] (R = Ph, 5). Deuterium labelling studies show that the mono-alkynyl complexes are formed via hydrogen transfer from a coordinated alkyne ligand to Ru-OH, while bis-alkynyl formation is proposed to take place through hydrogen transfer to Ru-H. Both 3 and 5 readily coordinate CO to give the corresponding dicarbonyl species 6 and 7. Addition of HC CPh to the hydride chloride precursor [Ru(IMes)(2)(CO) HCl] (2) results in a different reaction pathway involving alkyne insertion into the Ru-H bond to yield the alkenyl chloride complex [Ru(IMes)(2)(CO)(CH=CHPh)Cl] 8. Complexes 3-8 have been structurally characterised by X-ray crystallography. (C) 2008 Elsevier B.V. All rights reserved.

Microwave synthesis was used to grow single crystals of a new organic–inorganic supramolecular assembly, [V10O27(OH)] · 2(C6N2H14) · (C6N2H13) · (C6N2H12) · 2H2O, in a very short time compared to the conventional solution technique. In order to generate crystals suitable for single crystal experiments, an equimolar mixture of reactants and a few hours of microwave heating are required. Although non-merohedral twinning is an inherent problem, the crystal structure can be solved and refined in the orthorhombic space group Pna21 with a = 20.972(4) A, b = 10.3380(14) A, c = 20.432(3) A, Z = 4, with an excellent result, R(F2) = 0.0431. The assembly is hydrogen bond-assisted and built up of the monoprotonated decavanadate and 1,4-diazabicyclo[2.2.2]octane of various degrees of protonation. The number and location of protons on both the inorganic and organic motifs govern the formation of the extensive hydrogen bonding network, which in turn regulates the assembly architecture.

Cu(urea)2(H2O)3(NO3).(urea)(NO3) (1) and Zn(urea)4(H2O)2·2(NO3) (2) have been obtained from the corresponding metal nitrates and urea in warm aqueous solvent. These are unusual examples of complexes of transition metals coordinated only by urea and water. 1 crystallizes in the monoclinic space group P21/m with unit cell parameters a = 9.489(3), b = 13.059(3), c = 7.103(2) A and β = 100.28(3)°. The copper ion occupies a 2e position on a mirror plane and displays four short Cu–O bonds (2 × Cu–OH2 and 2 × Cu–O=C(NH2)2) and two much longer contacts (Cu–OH2 and Cu–ONO2) consistent with a Jahn–Teller distortion. Between the cations are located unbound urea and nitrate. 2 crystallizes in the monoclinic space group P21/n with a = 6.4239(11), b = 17.690(4), c = 7.5877(13) A and β = 91.138(14)°. The zinc ion resides on the 2a position, an inversion centre, and displays pseudo–octahedral coordination geometry. It is coordinated by four equatorial urea and two axial water molecules. The four molecules of urea are nearly planar and form N–H···O intramolecular hydrogen bonds. Unbound charge-balancing nitrate is also present. In each compound there is extensive intermolecular hydrogen bonding between the water, urea, and nitrate present. Pyrolysis of the compounds under 10% hydrogen in nitrogen at 300 °C was found to yield metallic copper in the case of 1 and zinc oxide for 2. The structures of two new metal urea nitrates have been determined at low temperature

The first example of polyoxovanadate layered framework with a cobalt coordination complex as a pillaring unit, CoII(μ-C2N2H8)2[V 4 IV V 2 V O14], was readily synthesized under hydrothermal conditions. The structure can be solved and refined in monoclinic P2 1 /n with a = 9.143(3) A, b = 6.5034(11) A, c = 15.874(4) A, β = 101.90(2), V = 923.6(4) A3 and Z = 2. The crystal structure comprises two-dimensional {V 4 IV V 2 V O14}2− layers extending parallel to [101], constructed from tetrahedral {VVO4} and square pyramidal {VIVO5} building units. Adjacent layers are linked through the octahedral {CoIIO2(μ-C2N2H8)2} pillars, within which the CoII resides on an inversion center. The structure displays N–H···O and C–H···O hydrogen bonding between the ethylenediamine and vanadium oxide layers. A new polyoxovanadate layered framework pillared with a cobalt coordination complex, CoII(μ-C2N2H8)2[V 4 IV V 2 V O14], has been prepared hydrothermally and fully characterized.

An important intermediate phase in the crystallization of aqueous solutions of sodium sulfate is the highly metastable sodium sulfate heptahydrate (Na(2)SO(4).7H(2)O). This has been structurally characterized for the first time by in situ single crystal X-ray diffraction. The crystal structure shows that each sodium cation is octahedrally coordinated to water molecules, with a slight distortion due to one of the water molecules being disordered. The hydrated sodium cations are hydrogen-bonded to form a three-dimensional bonded network, which is markedly different from the architecture of one-dimensional bonded chains observed in sodium sulfate decahydrate (mirabilite). This major structural difference explains the reconstructive nature of the transformation observed between the heptahydrate and mirabilite. High-pressure crystallization of a 3.41 mol/kg water aqueous solution of sodium sulfate at 1.54 GPa in a diamond-anvil cell resulted in the formation of a previously unknown sodium sulfate hydrate, which we have determined by single crystal X-ray diffraction methods to be an octahydrate, Na(2)SO(4).8H(2)O. In this structure the sulfate ions are coordinated directly to sodium ions. This resembles anhydrous sodium sulfate (thenardite) but contrasts with the heptahydrate and decahydrate in which the sodium ions are coordinated exclusively by water molecules. This observation demonstrates how the delicate balance of inter- and intramolecular bonds in the crystal structure can be significantly altered by the application of pressure.

A family of layered lanthanide hydroxyhalide intercalation hosts, Ln2(OH)5X·1.5H2O (X = Cl, Br; Ln = Y, Dy, Er, Yb), has been synthesized under hydrothermal conditions and their crystal structure determined. These are the first structures for the m = 1 members of the Ln2(OH)6−m(A)m·nH2O family of intercalation hosts to be determined. Reaction mixtures with Ln = Yb always yield a biphasic product which adopts an orthorhombic or monoclinic crystal structure. In both cases the layer composition is [Yb2(OH)5(H2O)1.5]+ and the Yb is eight or nine coordinated to bridging hydroxide anions and coordinated water molecules. Charge balancing halide anions are located in the interlayer gallery. The orthorhombic structure is adopted by the other chloride host lattices and the monoclinic one by Y2(OH)5Br·1.5H2O. These materials have been shown to undergo facile room temperature anion exchange reactions with a range of organic dicarboxylates.

A pillared-layered coordination polymer of formula Co(H2NCH2CH2NH2)SO4 (1) has been synthesized under solvothermal condition, and fully characterized. The three-dimensional structure of 1 is built up from cobalt sulfate sheets, each of which is composed of regularly alternating CoO4N2 octahedra and SO4 tetrahedra, with ethylenediamine pillars connecting the adjacent sheets. The coordinate covalent and hydrogen bonds have been revealed to exhibit an important role in the organization of the structure. The compound is found to be thermally stable up to, and above, 573 K and exhibits paramagnetic behavior at room temperature.

The reaction of the Schiff base species tris-((2-hydroxybenzylidene)aminoethyl)-amine (TrenSal) and tris-((2-hydroxy-5-bromobenzylidene)aminoethyl)amine (Tren5BrSal) with the acetates of nickel and zinc are reported. Two trimetallic complexes (M3L2) of Tren5BrSal with nickel and zinc have been crystallographically characterised. The attempted crystallisation of bis-(tris-((2-hydroxybenzylidene)aminoethyl)amine nickel) nickel from solutions containing TMEDA lead to the production of two novel complexes: namely a nickel adduct of the partially hydrolysed TrenSal ligand and an interesting nickel bromide–carbonate salt. [(TrenSal)2Ni3] is reacted with PbCl2 to form a novel tetrametallic complex, [{(TrenSal)Ni}Pb(NC5H5)Cl]2, where a Pb2Cl2 moiety replaces the nickel at the core of the complex. Extending the study to include the related hexadentate ligand, 1,1,1-tris-((2-hydroxybenzylidene)-aminomethyl)propane (TEtSal), we were able to isolate and characterise both [(TEtSal)2Ni3] and [{(TEtSal)Ni}2Pb].

The Potentiometric Cycling for Polymorph Creation [PC]2 has been applied to sparfloxacin, a third-generation fluoroquinolone antibiotic. Two different trihydrate phases precipitate from aqueous solution. X-ray data indicate that one of these is a previously unknown polymorph of sparfloxacin trihydrate. Because both forms crystallize from solution at the same time, the two crystalline forms are concomitant polymorphs that precipitate in a thermodynamically controlled ratio.

Complexes [Cu(phenpyzda)Cl2(H2O)]·H2O (1) and [Cu(phenpyzda)Br2(H2O)]·2H2O (2), where phenpyzda = pyrazino[2,3-f][1,10]phenanthroline-2,3-diamide, show similar molecular structures with square planar Cu(II). Each complex has a complicated three-dimensional (3D) hydrogen bonding network with 1 having an unusual 3,9-connectivity. Use of the corresponding carboxylic acid, pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarboxylic acid, results in the unexpected conversion of the ligand to 1H,3H-imidazol[2,3-f][1,10]phenanthroline (= imiphen) in the complex [CuCl3(imiphenH)]·2H2O, which has a 3D hydrogen bonded network structure of 3,6-connectivity. The more extended phenanthroline-based ligand 1,10-phenanthroline-5,6-[pteridine-2,4-diamine] was also synthesized, but no crystalline complexes of it were isolated. [Cu(bpy4diol)2](NO3)2·H2O (4), where bpy4diol = 2,2′-bipyridine-4,4′-diol, shows a two-dimensional (2D) hydrogen bonded network with hexagonal topology. [Cu(bpy4da)(NO3)2] (5) where bpy4da = 2,2′-bipyridine...

A series of four diaminoalkane templated vanadium oxide polymeric frameworks, [V 2 IV O8V 2 V O2](C2H10N2), [V 2 IV O8V 2 V O2](C3H12N2), [V 4 IV O10V 2 V O4](C4H14N2) and [V 4 IV O10V 2 V O4](C5H16N2), have been successfully prepared under hydrothermal conditions. The crystal structures are fully characterized revealing layered structures composed of common inorganic building units, namely {VIVO5} square pyramids and {VVO4} tetrahedra. The layer registries are different depending on the molecular structure of the diaminoalkanes, and can be accounted for by the organic-inorganic interface interactions. The analysis of hydrogen bonds indicates their important role in directing two- and three-dimensional structural architectures. The influences of different diaminoalkanes are also apparent in both thermogravimetric and complex magnetic behaviors, and are discussed in details.

A series of ruthenium hydride N-alkyl heterocyclic carbene complexes has been investigated as catalysts for a tandem oxidation/Wittig/reduction reaction to give C-C bonds from alcohols. The C-H-activated carbene complex Ru(IiPr(2)Me(2))'(PPh(3))(2)(CO)H (9) proves to be the most active precursor catalyzing the reaction of PhCH(2)OH and Ph(3)P=CHCN in 3 h at 70 degrees C. These results provide (a) a rare case in which N-alkyl carbenes afford higher catalytic activity than their N-aryl counterparts and (b) a novel example of the importance of NHC C-H activation in a catalytic cycle.

Synthetic details for 4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.5.2]pentadecane, the dimethyl ethylene cross-bridged homocyclen ligand are presented for the first time. Its novel Mn(2+), Fe(2+), Mn(3+), and Fe(3+) complexes have been synthesized and characterized. X-ray crystal structures were obtained for both manganese complexes, along with five additional Co(3+), Cu(2+), and Zn(2+) structures, the first structural characterization of complexes of this ligand. Each complex has the cis-V configuration of the cross-bridged macrocycle ring, leaving cis labile binding sites for interaction of the complex with oxidants and/or substrates. The copper(II) complex kinetic stability in 5 M HCl and at elevated temperatures was determined and compared to related complexes in the literature. The electronic properties of the manganese and iron complexes were evaluated using solid state magnetic moment determination and acetonitrile solution electronic spectroscopy, revealing high spin metal complexes in all cases. Cyclic voltammetry in acetonitrile of the divalent iron and manganese complexes revealed reversible redox processes, suggesting catalytic reactivity involving electron transfer processes are possible for both complexes. Screening of the Mn(2+) and Fe(2+) complexes for oxidation catalysis using hydrogen peroxide as the terminal oxidant showed both complexes are worthy of continued development.

Complexes of the type [Cu(L)2] (1) and [Cu4L2(μ4-O)(OAc)4] (2) have been obtained from the reaction of the phenoxydiimine 1,3-(2,6-R22C6H3NCH)2-5-R1C6H2OH-2 (LH) (where R1 = Me,tBu, Cl; R2 = Me, iPr) with copper(II) acetate [Cu(OAc)2]; changing the molar ratio of the reactants affords differing amounts of 1 or 2. Reaction of the parent dialdehyde [1,3-(CHO)2-5-MeC6H2OH-2] with [Cu(OAc)2] in the presence of Et3N afforded, following work-up, a polymeric chain (3) comprising {[Cu2(OAc)4]OAc}n, HNEt3 and MeCN. The crystal structures of 1 (R1 = Me, R2 = iPr1a; R1 = Cl, R2 = iPr 1b), 2 (R1 = Me, R2 = Me 2a; R1 = Me, R2 = iPr 2b; R1 = tBu, R2 = Me 2c; R1= Cl, R2 = Me 2d; R1 = Cl, R2 = iPr 2e; R1 = tBu, R2 = iPr 2f) and 3 are reported (synchrotron radiation was necessary for 3). The magnetic properties of the cluster 2b are presented. Complexes of type 2 and 3 were screened for the ring opening polymerization (ROP) of ε-caprolactone, with or without benzyl alcohol present, under a variety of conditions, however only trace polymer was isolated. The electrochemistry of all complexes was also investigated, together with their ability to catalyze benzene oxidation (using hydrogen peroxide); although low conversions were observed, the tetra-nuclear complexes exhibited excellent selectivity.

A series of new lanthanide coordination polymers has been synthesized and structurally characterized; [Ln4(TTHA)2(pzac)(H3O)2(H2O)]⋅5H2O (Ln = Pr (1a) and Nd (1b)), [Sm8(TTHA)4(pzac)0.5(H3O)(H2O)7.5]⋅4H2O (2), [Ln4(HTTHA)2(SO4)(H2O)4]⋅5H2O (Ln = Pr (3a) and Nd (3b)), where H6TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid, and H2pzac = 2,5-dioxo-piperazine-1,4-diacetic acid. The compounds feature three-dimensional frameworks comprising the deprotonated H6TTHA as the primary ligand and either the in situ generated pzac2- or sulfate as the secondary ligands. The influence of the deprotonated H6TTHA in directing the framework structures through preferential coordination modes and molecular conformation is described. The effect of the secondary ligands in increasing the compactness of the frameworks and in the alternation of the framework topologies based on the four-connected pts type is described.

Boron carbide is one of the lightest and hardest ceramics, but its applications are limited by its poor stability against a partial phase separation into separate boron and carbon. Phase separation is observed under high non-hydrostatic stress (both static and dynamic), resulting in amorphization. The phase separation is thought to occur in just one of the many naturally occurring polytypes in the material, and this raises the possibility of doping the boron carbide to eliminate this polytype. In this work, we have synthesized boron carbide doped with silicon. We have conducted a series of characterizations (transmission electron microscopy, scanning electron microscopy, Raman spectroscopy and X-ray diffraction) on pure and silicon-doped boron carbide following static compression to 50 GPa non-hydrostatic pressure. We find that the level of amorphization under static non-hydrostatic pressure is drastically reduced by the silicon-doping.

Variable temperature X-ray and neutron powder diffraction techniques have been used to identify structural phase transitions in Cu-rich A(3)A'BO(6) phases. A transition from monoclinic to rhombohedral symmetry was observed by X-ray diffraction between 700 and 500 K in Sr(3)Cu(1-x)M(x)IrO(6) (M = Ni, Zn; 0 < or = x < or = 0.5). The temperature of the phase change decreased in a linear manner with Cu-content and was essentially independent of the nature of M. Ca(3.1)Cu(0.9)MnO(6) was shown to pass from a rhombohedral phase to a triclinic phase on cooling below 290 K; the structure of the triclinic phase was refined against neutron diffraction data collected at 2 K. Ca(3.1)Cu(0.9)RuO(6) undergoes a transition between a disordered rhombohedral phase and an ordered monoclinic phase when cooled below 623 K. Neutron diffraction has been used to determine the structure as a function of temperature in the range 523 < or =T/K < or = 723 and hence to determine an order parameter for the low temperature phase; the second-order transition is shown to be incomplete 100 K below the critical temperature.

A homochiral microporous material is presented. The phase has 47% permanently porous void volume and is shown to have >1 nm diameter pores with three-dimensional channels using probe molecule sorption. Enantioselective guest sorption is strongly dependent on guest size. The homochiral microporous phase was identified by reactive selection from a first-generation chiral but nonporous framework. Chiral permanent porosity is established by directional noncovalent interactions between framework-forming and nonframework forming components of the stable second-generation material, which become stronger upon loss of the guests from the pore system.

Single crystals of Sr5Pb3NiO12 have been grown using a flux method and the structure, related to those of Sr5Pb3MO12 (M = Co or Cu), has been solved by single crystal X-ray methods in space group P $$\overline 6$$ 2m (a = 10.1356(11), c = 3.5337(3) A, V = 314.38(6) A3, Z = 1). The structure of Sr5Pb3NiO12 contains infinite chains of edge-sharing PbO6 octahedra which are linked together into trigonal pillars by Ni cations which adopt trigonal prismatic coordination. These pillars, which pack in a pseudo hcp array, are separated by strontium cations. There is evidence for some disorder at the prismatic sites.

The synthesis and characterisation of Ni2GaMo3N and the family of compounds Fe3-xCoxMo 3N, which crystallise with the η-carbide structure, are reported. A combination of magnetometry and diffraction experiments shows that they display Ni/Ga or Fe/Co metal-site ordering and, in the latter case, complex paramagnetism which does not vary in a uniform way with composition. All the compositions described here display metallic conductivity.

A new family of nitrides, Ni2-xM′xMo3N (M′=Co or Pd; 0≤x≤1.5), has been prepared pure by nitridation of commercially available crystalline metal oxides under reducing conditions (10% H2 in N2). The simple synthesis employs standard solid-state techniques and does not require the preparation of reactive precursors. Substitution of Ni by Co or Pd leads to a linear increase of the unit cell volume with composition. The temperature, composition, and magnetic-field dependence of the molar magnetisation suggest that the introduction of Co, but not Pd, increases the degree of electron localisation in Ni2-xM′xMo3N. The same synthetic method has also lead to the formation, in mixtures, of the new phases π-Co2Mo3N and Pd2N. © 2003 Elsevier Science (USA). All rights reserved.