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A variety of novel magnesium complexes containing sp (alkynyl) or sp2 (imido) hybridized ligands were synthesized utilizing both deprotonative and addition routes. Spectroscopic and structural analysis revealed 4, 5, and 6-coordinate complexes, both hetero- and homoleptic. [Display omitted] As a metallic element of high natural abundance, magnesium finds a wide range of uses in both stoichiometric and more recently catalytic applications. This often takes advantage of the basic or nucleophilic properties of its compounds or their ability to co-complex with other organometallic compounds. However, the homoleptic chemistry of Mg(II) is heavily skewed towards alkyl and aryl ligands bound via sp2 and sp3 hybridized atoms. Here, we report our combined NMR spectroscopic and X-ray crystallographic study into much rarer alternative THF solvates of homoleptic magnesium complexes using ligands which bind via sp (alkynyl) and sp2 (imido) atoms. Specifically, we exploit the high acidity of terminal alkynes and diphenylacetonitrile to prepare tetra-solvated distorted octahedral complexes Mg(C≡CC 6 H 4 R- p) 2 (THF) 4 (R = Me, CF 3) and Mg(N=C=CPh 2) 2 (THF) 4 starting from the commercial alkyl reagent MgBu 2. Adopting a similar deprotonative strategy using benzophenoneimine Ph 2 C=NH affords the heteroleptic trinuclear complex Mg 3 (N=CPh 2) 4 n Bu 2 (THF) 2 with distorted tetrahedral Mg centres. Related imidomagnesium halide complexes can be accessed either by deprotonation of the imine with a Grignard reagent, or nucleophilic addition of a Grignard reagent to a nitrile, but these unusual five-coordinate complexes are unresponsive to a 1,4-dioxane induced Schlenk equilibrium shift. Employing a higher reflux temperature switching from a THF to a toluene medium permits access to the THF solvate of a homoleptic imido complex which also possesses a trinuclear constitution in Mg 3 (N=CPh 2) 6 (THF) 2. [ABSTRACT FROM AUTHOR]

The synthesis and XRD characterization at 295 K of three isomers, X-fluoro-N-(2-hydroxy-5-methyl phenyl) benzamide: (o-FPhB), (m-FPhB), and (p-FPhB), are presented. o-FPhB and m-FPhB show high structural affinity concerning molecular and packing structures. The planarity of the C1-C7(O1)-N1-C8 peptide bond in o-FPhB, and m-FPhB confers high stability, favoring its tendency to acquire a resonant structure in the peptide segment and in the molecule. For p-FPhB, a stereochemical gate opens, leading to the activation of N-H∙∙∙∙O interpeptide bonds, defining its supramolecular properties. Active participation of the halogen in the assembly of the structures is observed, forming intramolecular rings and molecule chains during crystal growth. The o-FPhB and m-FPhB form parallel sheets that develop hydrogen C-H···Cg, halogen C-F···Cg, or C=O···Cg interactions. Theoretical evaluations of the properties performed by the DFT/B3LYP/(6-311G(d,p) showed good agreement with the experimental values. The IR analysis reaffirms the presence of N-H, C=O, O-H, C-F, and C-H. In the UV-Vis, an increase in the energetic stability, O···H interactions, and electrostatic potential in the NH region reaffirm the disposition of p-FPhB for the formation of the N-H···O interpeptide bond. A molecular docking on the benzamides involving protein receptors showed similar behavior for all three isomers. [ABSTRACT FROM AUTHOR]

Abstract: Expanding the scope and applications of anionic N‐heterocyclic carbenes (NHCs), a novel series of magnesium NHC complexes is reported using a mixed sodium–magnesium approach. Sequential reactivity of classical imidazol‐ 2‐ylidene carbene IPr with NaR and MgR2 (R=CH2SiMe3) affords [(THF)3Na(μ‐IPr−)MgR2(THF)] (2) [IPr−=:C{[N(2,6‐iPr2C6H3)]2CHC] containing an anionic NHC ligand, whereas surprisingly sodium magnesiate [NaMgR3] fails to deprotonate IPr affording instead the redistribution coordination adduct [IPr2Na2MgR4] (1). Compound 2 undergoes selective C2‐methylation when treated with MeOTf furnishing novel abnormal NHC complex [{aIPrMeMgR2}2] (3). Dissolving 3 in THF led to the dissociation of this complex into MgR2 and aIPrMe with the latter isomerizing to the olefinic NHC IPr=CH2. The ability of 2 and 3 to transfer their anionic and abnormal NHC ligands, respectively to AuI metal fragments has been investigated allowing the isolation and structural characterization of [RAu(μ‐IPr−)MgR(THF)2] (4) and [aIPrMeAuR] (5) respectively. In both cases transfer of an alkyl R group is observed. However while 3 can also transfer its abnormal NHC ligand to give 5, in 4 the anionic NHC still remains coordinated to Mg via its C4 position, whereas the {AuR} fragment occupies the C2 position previously filled by a donor‐solvated {Na(THF)3}+ cation. [ABSTRACT FROM AUTHOR]

Metallic tungsten (W) was initially assumed to be environmentally benign and a green alternative to lead. However, subsequent investigations showed that fishing weights and munitions containing elemental W can fragment and oxidize into complex monomeric and polymeric tungstate (WO 4 ) species in the environment; this led to increased solubility and mobility in soils and increased bioaccumulation potential in plant and animal tissues. Here we expand on the results of our previous research, which examined tungsten toxicity, bioaccumulation, and compartmentalization into organisms, and present in this research that the bioaccumulation of W was related to greater than 50% reduction in the mechanical properties of the snail ( Otala lactea ), based on depth-sensing nanoindentation. Synchrotron-based X-ray fluorescence maps and X-ray diffraction measurements confirm the integration of W in newly formed layers of the shell matrix with the observed changes in shell biomechanical properties, mineralogical composition, and crystal orientation. With further development, this technology could be employed as a biomonitoring tool for historic metals contamination since unlike the more heavily studied bioaccumulation into soft tissue, shell tissue does not actively eliminate contaminants. [ABSTRACT FROM AUTHOR]

Organometallic bases are becoming increasingly complex, because mixing components can lead to bases superior to single-component bases. To better understand this superiority, it is useful to study metalated intermediate structures prior to quenching. This study is on 1-phenyl-1 H-benzotriazole, which was previously deprotonated by an in situ ZnCl2 ⋅TMEDA/LiTMP (TMEDA= N, N, N′, N′-tetramethylethylenediamine; TMP=2,2,6,6-tetramethylpiperidide) mixture and then iodinated. Herein, reaction with LiTMP exposes the deficiency of the single-component base as the crystalline product obtained was [{4-R-1-(2-lithiophenyl)-1 H-benzotriazole ⋅3THF}2], [R=2-C6H4(Ph)NLi], in which ring opening of benzotriazole and N2 extrusion had occurred. Supporting lithiation by adding iBu2Al(TMP) induces trans-metal trapping, in which CLi bonds transform into CAl bonds to stabilise the metalated intermediate. X-ray diffraction studies revealed homodimeric [(4-R′-1-phenyl-1 H-benzotriazole)2], [R′=( iBu)2Al(μ-TMP)Li], and its heterodimeric isomer [(4-R′-1-phenyl-1 H-benzotriazole){2-R′-1-phenyl-1 H-benzotriazole}], whose structure and slow conformational dynamics were probed by solution NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Synthetically important for introducing a picolyl scaffold into a molecular construction, alkali metallated picoline (methylpyridine) complexes are also interesting in their own right for the diversity of their ligand metal bonding possibilities. Here the syntheses of seven new such complexes are reported: namely three 4-picoline derivatives 4-picLi·Me6TREN, 1, 4-picNa·Me6TREN, 2, and [4-picK·2(4-picH)]∞, 3; and four 2-picoline derivatives, 2-picLi·Me6TREN, 4, 2-picLi·PMDETA, 4', 2-picNa·Me6TREN, 5, and [2-picK·PMDETA]2, 6' [where pic = NC5H4(CH2); Me6TREN = tris(N,N-dimethyl-2-aminoethyl)amine, (Me2NCH2CH2)3N; PMDETA = N,N,N',N'',N''-pentamethyldiethylenetriamine, (Me2NCH2CH2)2NMe]. X-ray crystallographic studies establish that the lighter alkali metal complexes 1, 2, 4' and 5 adopt monomeric structures in contrast to the polymeric and dimeric arrangements adopted by potassium complexes 3 and 6' respectively. All complexes have also been characterized by solution NMR spectroscopy (¹H, 13C, and where relevant 7Li). This study represents the first example of sodium and potassium picolyl complexes to be isolated and characterized. DOSY (Diffusion-Ordered Spectroscopy) experiments performed on 4 and 4' suggest both compounds retain their monomeric constitutions in C6D6 solution. Discussion focuses on the influence of the metal and neutral donor molecule on the structures and the nature of the ligand. metal (enamido versus aza-allylic) interactions. [ABSTRACT FROM AUTHOR]

The structures of two anhydrous salt phases of theophylline, namely 1,3-dimethyl-2,6-dioxo-7 H-purin-9-ium tetrafluoroborate, C7H9N4O2+·BF4−, and 1,3-dimethyl-2,6-dioxo-7 H-purin-9-ium chloride, C7H9N4O2+·Cl−, are reported together with the structures of two monohydrate salt forms, namely 1,3-dimethyl-2,6-dioxo-7 H-purin-9-ium chloride monohydrate, C7H9N4O2+·Cl−·H2O, and 1,3-dimethyl-2,6-dioxo-7 H-purin-9-ium bromide monohydrate, C7H9N4O2+·Br−·H2O. The monohydrate structures are mutually isostructural, with the cations and anions lying on crystallographic mirror planes ( Z′ = ). The main intermolecular interaction motif is a hydrogen-bonding network in the same mirror plane. The tetrafluoroborate structure is based on planar hydrogen-bonded theopylline cation dimers; the anions interact with the dimers in a pendant fashion. The anhydrous chloride structure has Z′ = 2 and in contrast to the other species it does not form planar hydrogen-bonded constructs, instead one-dimensional chains of cations and anions propagate parallel to the crystallographic c direction. An earlier report claiming to describe an anhydrous structure of theophylline hydrochloride is re-examined in light of these results. It is concluded that the earlier structure has been reported in the wrong space group and that it has been chemically misidentified. [ABSTRACT FROM AUTHOR]

Lithium 2,2,6,6-tetramethylpiperidide (LiTMP), one of the most important polar organometallic reagents both in its own right and as a key component of ate compositions, has long been known for its classic cyclotetrameric (LiTMP)4 solid-state structure. Made by a new approach through transmetalation of Zn(TMP)2 with tBuLi in n-hexane solution, a crystalline polymorph of LiTMP has been uncovered. X-ray crystallographic studies at 123(2) K revealed this polymorph crystallises in the hexagonal space group P63/ m and exhibited a discrete cyclotrimeric ( C3 h) structure with a strictly planar (LiN)3 ring containing three symmetrically equivalent TMP chair-shaped ligands. The molecular structure of (LiTMP)4 was redetermined at 123(2) K, because its original crystallographic characterisation was done at ambient temperature. This improved redetermination confirmed a monoclinic C2/ c space group with the planar (LiN)4 ring possessing pseudo (non-crystallographic) C4 h symmetry. Investigation of both metalation and transmetalation routes to LiTMP under different conditions established that polymorph formation did not depend on the route employed but rather the temperature of crystallisation. Low-temperature (freezer at −35 °C) cooling of the reaction solution favoured (LiTMP)3; whereas high-temperature (bench) storage favoured (LiTMP)4. Routine 1H and 13C NMR spectroscopic studies in a variety of solvents showed that (LiTMP)3 and (LiTMP)4 exist in equilibrium, whereas 1H DOSY NMR studies gave diffusion coefficient results consistent with their relative sizes. [ABSTRACT FROM AUTHOR]

Insertion of CO2into the metal–N bond of a series of synthetically important alkali-metal TMP (2,2,6,6-tetramethylpiperidide) complexes has been studied. Determined by X-ray crystallography, the molecular structure of the TMEDA-solvated Li derivative shows a central 8-membered (LiOCO)2ring lying in a chair conformation with distorted tetrahedral lithium centres. While trying to obtain crystals of a THF-solvated derivative, a mixed carbonato/carbamato dodecanuclear lithium cluster was formed containing two central (CO3)2−fragments and eight O2CTMP ligands with four distinct bonding modes. A bisalkylaluminium carbamato complex has also been prepared viatwo different methods (CO2insertion into a pre-formed Al–N bond and ligand transfer from the corresponding lithium reagent) which adopts a dimeric structure in the solid state. [ABSTRACT FROM AUTHOR]

Describes the crystal structure of a novel organic compound. Van der Waals contacts; Displacement ellipsoids; Methylene chains; Hydrogen bonding; Centroid; Linkage of inversion-related molecules; Aromatic ring rotation.

Studies the crystal structure of three fluoro-substituted acetoacetanilides. Planar structure with intramolecular hydrogen bonding; Orientation of the ketone carbonyl group with respect to the amide; Effect of a fluorine substituent on crystal packing.

Addition of lithium hexamethyldisilazide to an equimolar amount of calcium bis(hexamethyldisilazide) in toluene gave ‘solvent-free’, [Li{μ-N(SiMe3)2}2Ca{N(SiMe3)2}] (1). An X-ray study reveals a dinuclear arrangement based on a planar LiNCaN four-membered ring: both metals engage in additional H3C⋯M (where M=Li, Ca) interactions with the μ-N(SiMe3)2 substituents resulting in a distorted tetrahedral geometry at lithium and a distorted trigonal-bipyramidal geometry at calcium. This contrasts with the previously reported mixed Li–Mg analogue, [Li{μ-N(SiMe3)2}2Mg{N(SiMe3)2}], where only the lithium centre engages in such intramolecular agostic H3C⋯Li interactions. [Copyright &y& Elsevier]

The study of co-complexation reactions between NaCH2SiMe3and Mg(CH2SiMe3)2has allowed the isolation and structural elucidation of the first solvent-free alkali-metal alkylmagnesiate [{NaMg(CH2SiMe3)3}∞] (1) as well as the related solvent-free sodium alkyl [{(NaCH2SiMe3)4}∞] (3). [ABSTRACT FROM AUTHOR]

A new application of zincate [(THF)Li(TMP)(tBu)Zn(tBu)] (1) in alkali-metal mediated zincation (AMMZn) is reported by isolating and structurally defining the first intermediates of direct lateral zincation (DlZn) of trimethyl(phenoxy)silane (2) both of which adopt novel six-element {ZnCSiOLiN} ring structures. [ABSTRACT FROM AUTHOR]

Crystallographic studies of monosulfonated azo dyes have concentrated on the salt forms that contain the azo anion. Here we present a study that compares the structures of these anions with protonated free acid forms and with doubly deprotonated dianion forms. To this end, the new single crystal diffraction structures of 13 systematically related free acid forms of monosulfonated azo dyes are presented, together with three new structures of doubly deprotonated forms and two new structures of Na salt forms of azo anions. No structures of dideprotonated monosulfonated azo dyes have previously been reported and this paper also reports the first crystal structure of an azo dye with a hydronium cation. The geometries of the free acid, anion and dianion forms are compared to literature equivalents. It is shown that protonation of the azo bond gives predictable bond lengthening and shortening, which is of a greater magnitude than similar effects caused by azo-hydrazone tautomerisation, or the smaller again effects caused by the resonance electron donation from O or N based substituents. The dianion containing structures have twisted dianion geometries that can be understood based on the resonance effects of the phenoxide groups and upon the needs to bond to a relatively high number of metal cations. [ABSTRACT FROM AUTHOR]

Both the molecular and the crystal structures of the title compound, C9H14N2O2S, are similar to those of its 4-phenyl analogue. The supramolecular network is based upon N—H⋯N hydrogen-bonded centrosymmetric dimers linked by N—H⋯O contacts. [ABSTRACT FROM AUTHOR]

Evaluates the crystal structure of a centrosymmetric dimer of lithium chloride with terminal chloride anions. Neutral Lewis base complexes of lithium chloride; Molecular structure showing the atom-numbering scheme and probability displacement ellipsoids; Terminal donor ligands; Formation of the charge-separated complex; Selected geometric parameters.

The title compound, {(C10H16N)[Cd(SCN)3]} n, contains [(C6H5CH2)N(CH3)3]+ cations lying between one-dimensional chains of stoichiometry {[Cd(SCN)3]−} n. Each CdII ion is 3 N,3 S-hexa­coordinated by thio­cyanate ligands, in an octa­hedral fac arrangement. The asymmetric unit contains two cations and two anions. [ABSTRACT FROM AUTHOR]

Hydro­chloro­thia­zide forms a 1:2 solvate with N, N-dimethyl­acetamide (systematic name: 6-chloro-3,4-dihydro-2 H-1,2,4-benzothia­diazine-7-sulfonamide 1,1-dioxide dimethyl­acet­amide disolvate), C7H8ClN3O4S2·2C4H9NO. The compound crystallizes with one hydro­chorothia­zide and two disordered solvent mol­ecules in the asymmetric unit, with a hydrogen-bonding network comprising four N—H⋯O contacts. [ABSTRACT FROM AUTHOR]

The heterometallic alkoxide catena-poly[[tetra-μ2- tert-butoxo-1:2κ4 O: O;1:3κ4 O: O-bis(tetrahydrofuran)-2κ O,3κ O-iron(III)dilithium(I)]-μ-bromo], [FeLi2Br(C4H9O)4(C4H8O)2] n, forms a one-dimensional chain through an a-glide. This conformation is achieved through the formation of FeIII/O/Li/O rings and Li—Br—Li bridges. [ABSTRACT FROM AUTHOR]

Hydro­chloro­thia­zide forms a 1:1 solvate with 1,4-dioxane, C7H8ClN3O4S2·C4H8O2 [systematic name: 6-chloro-3,4-di­hydro-2 H-1,2,4-benzothia­diazine-7-sulfonamide 1,1-dioxide–1,4-dioxane ( )]. The asymmetric unit comprises one mol­ecule of hydro­chloro­thia­zide and halves of two solvent mol­ecules arranged around inversion centres. The structure contains a hydrogen-bonding network comprising three N—H⋯O and one N—H⋯N hydrogen bonds. [ABSTRACT FROM AUTHOR]

Abstract: A series of cis and trans tetradentate copper macrocyclic complexes, of ring size 14–16, that employ amine and thioether donor groups are reported. Apart from 5,6,15,16-bisbenzo-8,13-diaza-1,4-dithia-cyclohexadecane copper(I) (cis-[Cu(H4NbuSen)]+) all of the complexes are obtained in the copper(II) form. Crystallographic analysis shows that the copper(II) complexes all adopt a distorted planar geometry around the copper. In contrast, cis-[Cu(H4NbuSen)]+ is found to adopt a distorted tetrahedral geometry. The complexes were subjected to electrochemical analysis in water and acetonitrile. The effect of the solvent, positions of the donor atoms (cis/trans) on E 1/2 is discussed as is the comparison of the electrochemical behaviour of these complexes with their parent Schiff base macrocycles. [Copyright &y& Elsevier]

The solvate structure of 3,4-dichloro-1-nitro­benzene with aniline, 2C6H3Cl2NO2·C6H7N, is reported. Ribbons of 3,4-dichloro­nitro­benzene, formed by Cl⋯Cl and N—O⋯Cl inter­actions, are linked together via N—H⋯O hydrogen bonds with aniline into an undulating two-dimensional sheet. [ABSTRACT FROM AUTHOR]