Cl Distances Research Articles

High-resolution Measurement of Contact Ion-pair Structures in Aqueous RbCl Solutions from the Simultaneous Corefinement of their Rb and Cl K-edge XAFS and XRD Spectra

In concentrated solutions of aqueous RbCl, all of the Rb+ and Cl– ions exist as contact ion pairs. This full structural assessment is derived from the refinement of three independent experimental measurements: the Rb and Cl K-edge X-ray absorption fine structure (XAFS) and the X-ray diffraction spectra (XRD). This simultaneous refinement of the XAFS and XRD data provides high accuracy since each method probes the structure of different local regions about the ions with high sensitivity. At high RbCl concentration (6 mol·kg–1) the solution is dominated by Rb+–Cl– contact ion pairs yielding an average of 1.5 pairs at an Rb–Cl distance of 3.24 A. Upon formation of these ion pairs, approximately 1.1 waters molecules are displaced from the Rb+ and 1.4 water molecules from Cl–. The hydration shells about both the cation and anion are also determined. These results greatly improve the understanding of monovalent ions and provide a basis for testing the Rb+–Cl– interaction potentials used in molecular dynamics (MD) simulation.

Influence of external electric field on the transfer of protons in hydrogen-bonded systems

The LCAO MO self-consistent field method in combination with the 6-31** basis set is used to calculate sections of the potential energy surface for a proton in the NH3…HCl system in the presence of an external electrostatic field. The field strength is varied in the range of 0.000 to 0.017 a. u. In the absence of the field, the potential of the proton in the isolated complex has one well, the N–Cl distance is equal to 2.92 A, and the NH3…H–Cl bond is a hydrogen bond. With increasing distance between the N and Cl atoms, a second well appears in the potential, with the well near the Cl atom remaining deeper. In the presence of an external electric field, with increasing its strength, the depth of the well near the N atom increases, while the height of the barrier for proton transfer from the chlorine to the nitrogen atom decreases. At a certain field strength, the well near the nitrogen atom becomes deeper than that near the chlorine atom, so the proton moves to the nitrogen, making the complex ionic. Thus, the external electric field can influence the type of chemical bond in NH3…HCl system.

Length–length and length–weight relationships of Carcharhinus falciformis and C. signatus (Carcharhinidae: Carcharhinus) caught by commercial fisheries in the Southwest Atlantic Ocean

Sharks of the genus Carcharhinus are captured as bycatch in longline fisheries and through different fishing gears. Due to the common practice of head and fin removal of sharks, the lack of morphometric data and weight on landings by species hinders the implementation of management measures, since they are needed to perform a stock assessment. Here, we present the length–length (LLR) and length–weight (LWR) relationships of the silky shark (n=145) and night shark (n=90) caught by the commercial pelagic longline fisheries in the Southwest Atlantic Ocean (22°S–33°S; 25°W–50°W) between April 2009 and August 2010. All length–length and length–weight relationships were extremely significant with the coefficient of determination (r2) ranging around 0.99. There were no significant differences in the regression parameters of the length–length and length–weight relationships between males and females to both species. These results represent the first reference on the LLRs and LWRs to silky shark and night shark, using the carcass length (CL—distance between the origin of the pectoral fin to the origin of the caudal fin, in cm) as the basis for all conversion factors.

Crystal structure of bis-(N-tert-butyl-benzamidinium) hexa-chlorido-zirconate(IV) di-chloro-methane disolvate.

In the Zr(IV) complex anion of the title complex salt, [(C4H9)HNC(C6H5)NH2]2[ZrCl6]·2CH2Cl2, the Zr(IV) cation, located on an inversion centre, is coordinated by six Cl(-) anions in a distorted octa-hedral geometry with Zr-Cl distances in the range 2.433 (2)-2.4687 (19) Å; in the amidinium cation, the dihedral angle between the aromatic ring and [NCN] plane is 43.3 (4)°. In the crystal, the amidinium cations and [ZrCl6](2-) anions are linked by N-H⋯Cl hydrogen bonds, forming a two-dimensional network extending along the b axis; two di-chloro-methane solvent mol-ecules are linked by a pair of weak C-H⋯Cl hydrogen bonds, forming a centrosymmetric [CHCl]2 six-membered ring.

(Acetato-κO){2-[(2-aminoethyl-κN)disulfanyl]ethanaminium}dichloridozinc(II)

In the title compound, [Zn(C4H13N2S2)(CH3COO)Cl2], the ZnIIion is in a tetrahedral coordination geometry, coordinated by one acetate, two chloride and one 2-[(2-aminoethyl)disulfanyl]ethanaminium ligand, with a Zn—O distance of 1.977 (3) Å, a Zn—N distance of 2.015 (3) Å and Zn—Cl distances of 2.2673 (18) and 2.2688 (15) Å. In the crystal, molecules are self-assembled by N—H...Cl hydrogen bonds, leading to a one-dimensional chain structure. The chains interact with each other through N—H...O, N—H...S, C—H...Cl and C—H...S hydrogen bonding, completing a three-dimensional hydrogen-bonding network structure.

Crystal structure of [bis-(2-amino-ethyl-κN)(2-{[4-(tri-fluoro-meth-yl)benzyl-idene]amino}-eth-yl)amine-κN]di-chlorido-copper(II).

The Cu(II) atom in the title compound, [CuCl2(C14H21F3N4)], adopts a coordination geometry that is between distorted square-based pyramidal and very Jahn-Teller-elongated octa-hedral. It is coordinated by three N atoms from the bis-(2-amino-eth-yl)(2-{[4-(tri-fluoro-meth-yl)benzyl-idene]amino}-eth-yl)amine and two chloride ligands. The two crystallographically unique copper complexes present in the asymmetric unit exhibit noticeable differences in the coordination bond lengths. Considering the Cu(II) atoms as having square-pyramidal geometry, the basal Cu-Cl bond lengths are typical [2.2701 (12) and 2.2777 (12) Å], while the apical distances are considerably elongated [2.8505 (12) and 2.9415 (12) Å]. For each mol-ecule, a Cu(II) atom from inversion-related mol-ecules are in nearby proximity to the remaining axial Cu(II) sites, but the Cu⋯Cl distances are very long [3.4056 (12) and 3.1645 (12) Å], attributable to van der Waals contacts. Nonetheless, these contacts appear to have some structure-directing properties, leading to association into dimers. These dimers associate via stacking of the aromatic rings to form extended zigzag chains.

Crystal structure of catena-poly[N,N,N',N'-tetra-methyl-guanidinium [(chlorido-cadmate)-di-μ-chlorido]

In the structure of the title salt, {(C5H14N3)[CdCl3]} n , the Cd(II) atom of the complex anion is five-coordinated by one terminal and four bridging Cl atoms. The corresponding coordination polyhedron is a distorted trigonal bipyramid, with Cd-Cl distances in the range 2.4829 (4)-2.6402 (4) Å. The bipyramids are condensed into a polyanionic zigzag chain extending parallel to [101]. The tetra-methyl-guanidinium cations are situated between the polyanionic chains and are linked to them through N-H⋯Cl hydrogen bonds, forming a layered network parallel to (010).

Higher coordinate gold(I) complexes with the weak Lewis base tri(4-fluorophenyl) phosphine. Synthesis, structural, luminescence, and DFT studies

The structures and spectroscopic properties of two high coordinate gold(I) phosphine complexes with the TFFPP=tri(4-fluorophenyl)phosphine ligand are reported. Synthesis in a 1:3 metal to ligand ratio provided the compound [AuCl(TFFPP)3] (2) that crystallize in the P1¯ space group, where the asymmetric unit consists of three independent molecules. In all three sites, two sets of bond angles display distinctly different ranges. The three P–Au–P angles have average values of 117.92°, 117.57°, and 114.78° for sites A, B, and C, with the corresponding P–Au–Cl angles of 98.31°, 99.05°, and 103.38°, respectively. The chloride ion coordinates as the fourth ligand, at the corresponding Au–Cl distance of 2.7337, 2.6825, and 2.6951 Å for the three sites. This distance is longer by 0.40–0.45 Å than the Au–Cl distance found in the mono TFFPP complex 1 (2.285 Å) indicating a weakening of the Au–Cl interaction as the coordination number increases. In compound 3, [Au(TFFPP)3]Cl·½CH2Cl2·H2O, the structure consists of three phosphine ligands bound to the gold(I) atom, but the Cl− exists as uncoordinated counter anion. The structural differences observed in the two complexes are attributable to crystal-packing effects caused by the introduction of H-bonding as well as enhanced intra and inter-molecular π-interaction in 3. The photoluminescence of the complexes compared with that of the ligand show ligand centered emission perturbed by the metal coordination. Theoretical DFT studies conducted on these complexes supports assignments of the electronic transitions observed in these systems.

Crystal structure of catena-poly[1,3-di-benzyl-benzimidazolium [[chlorido-mercurate(II)]-di-μ-chlorido]

The asymmetric unit of the polymeric title compound, {(C21H19N2)[HgCl3]}n, comprises one-half of the cationic mol­ecule, the other half being generated by application of twofold rotation symmetry, one Hg and two Cl atoms. The HgII atom, lying on a twofold rotation axis, exhibits a distorted triangular coordination environment and is surrounded by three Cl atoms with Hg—Cl distances in the range 2.359 (2)–2.4754 (13) Å. Two additional longer distances [Hg⋯Cl = 3.104 (14) Å] lead to the formation of polymeric [HgCl1/1Cl4/2]− chains extending along [001]. The crystal packing can be described by cationic layers alternating parallel to (-110) with the anionic chains located between the layers. The packing is consolidated by π–π stacking inter­actions between the benzene rings of the central benzimidazole entities, with centroid-to-centroid distances of 3.643 (3) Å.

Crystal structures of tris-[1-oxo-pyridine-2-olato(1-)]silicon(IV) chloride chloro-form-d 1 disolvate, tris-[1-oxo-pyridine-2-olato(1-)]silicon(IV) chloride aceto-nitrile unqu-anti-fied solvate, and fac-tris-[1-oxo-pyridine-2-thiol-ato(1-)]silicon(IV) chloride chloro-form-d 1 disolvate.

The cations in the title salts, [Si(OPO)3]Cl·2CDCl3, (I), [Si(OPO)3]Cl·xCH3CN, (II), and fac-[Si(OPTO)3]Cl·2CDCl3, (III) (OPO = 1-oxo-2-pyridin-one, C5H4NO2, and OPTO = 1-oxo-2-pyridine-thione, C5H4NOS), have distorted octa-hedral coordination spheres. The first two structures contain the same cation and anion, but different solvents of crystallization led to different solvates and packing arrangements. In structures (I) and (III), the silicon complex cations and chloride anions are well separated, while in (II), there are two C-H⋯Cl distances that fall just within the sum of the van der Waals radii of the C and Cl atoms. The pyridine portions of the OPO ligands in (I) and (II) are modeled as disordered with the planar flips of themselves [(I): 0.574 (15):0.426 (15), 0.696 (15):0.304 (15), and 0.621 (15):0.379 (15); (II): 0.555 (13):0.445 (13), 0.604 (14):0.396 (14) and 0.611 (13):0.389 (13)], demonstrating that both fac and mer isomers are co-crystallized. In (II), highly disordered solvent, located in two independent channels along [100], was unable to be modeled. Reflection contributions from this solvent were fixed and added to the calculated structure factors using the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] function of program PLATON, which determined there to be 54 electrons in 225 Å(3) accounted for per unit cell (25 electrons in 109 Å(3) in one channel, and 29 electrons in 115 Å(3) in the other). In (I) and (II), all species lie on general positions. In (III), all species are located along crystallographic threefold axes.

Crystal structure of bis-(4-acetyl-anilinium) tetra-chlorido-mercurate(II).

The structure of the title salt, (C8H10NO)2[HgCl4], is isotypic with that of the cuprate(II) and cobaltate(II) analogues. The asymmetric unit contains one 4-acetyl­anilinium cation and one half of a tetra­chlorido­mercurate(II) anion (point group symmetry m). The Hg—Cl distances are in the range 2.4308 (7)–2.5244 (11) Å and the Cl—Hg—Cl angles in the range of 104.66 (2)–122.94 (4)°, indicating a considerable distortion of the tetra­hedral anion. In the crystal, cations are linked by an inter­molecular N—H⋯O hydrogen-bonding inter­action, leading to a C(8) chain motif with the chains extending parallel to the b axis. There is also a π–π stacking inter­action with a centroid-to-centroid distance of 3.735 (2) Å between neighbouring benzene rings along this direction. The anions lie between the chains and inter­act with the cations through inter­molecular N—H⋯Cl hydrogen bonds, leading to the formation of a three-dimensional network structure.

Crystal structure of bis-(4-acetyl-anilinium) tetra-chlorido-cobaltate(II).

The structure of the title salt, (C8H10NO)2[CoCl4], is isotypic with the analogous cuprate(II) structure. The asymmetric unit contains one 4-acetyl­anilinium cation and one half of a tetra­chlorido­cobaltate(II) anion for which the CoII atom and two Cl− ligands lie on a mirror plane. The Co—Cl distances in the distorted tetra­hedral anion range from 2.2519 (6) to 2.2954 (9) Å and the Cl—Co—Cl angles range from 106.53 (2) to 110.81 (4)°. In the crystal, cations are self-assembled by inter­molecular N—H⋯O hydrogen-bonding inter­actions, leading to a C(8) chain motif with the chains running parallel to the b axis. π–π stacking inter­actions between benzene rings, with a centroid-to-centroid distance of 3.709 Å, are also observed along this direction. The CoCl4 2− anions are sandwiched between the cationic chains and inter­act with each other through inter­molecular N—H⋯Cl hydrogen-bonding inter­actions, forming a three-dimensional network structure.

Trigonal Bipyramid Ni3Cl3O2 Cluster Showing the High-Spin S = 3 Ground State with Uniaxial Magnetic Anisotropy

Abstract We have prepared a novel nickel(II) trinuclear compound [Ni3(tmen)3(µ2-Cl)3(µ3-OMe)(µ3-OH)](BPh4)·0.5MeOH·0.5CH2Cl2 (1; tmen: N,N,N′,N′-tetramethylethylenediamine) with a trigonal bipyramid molecular structure, where the basal plane consists of Ni3(µ2-Cl)3 atoms. Two known compounds [Ni3(tmen)3X4(OH)]X (X = Cl (2), Br (3)) were also investigated. Magnetic study clarified the ground high-spin (S = 3) state, and the intramolecular exchange coupling parameters were determined as 2J/kB = 18.0 ± 0.2, 27.2 ± 0.2, and 19.6 ± 0.2 K for 1, 2, and 3, respectively. Crystallographic analysis clarified the unique geometry of 1. The molecular axes are aligned almost parallel in the crystallographic b axis. Relatively short intermolecular Cl···Cl distances (3.725(1) and 3.847(2) Å) are found among linearly arrayed complex ions. A single-crystal magnetic study gave a zero-field-splitting parameter DS=3/kB = −2.2 ± 0.1 K. An intermolecular exchange coupling parameter was determined as 2j/kB = −0.15 ± 0.01 K from simulation. A pulsed-field magnetization study at 0.5 K for 1 showed a jump around 1.2 T, which is explained in terms of intermolecular interaction. Alternating current magnetic susceptibility measurements revealed the Arrhenius behavior with Ea = 10.1 ± 0.8 K at zero bias field. Therefore, the magnetic properties of 1 can be understood as an antiferromagnetic chain made of potential single-molecule magnets.

The crystal structures of tetra-kis-(μ-n-butyrato-κ(2) O:O')bis[bromidorhenium(III)] and tetra-kis-(μ-n-butyrato-κ(2) O:O')bis[chlorido-rhenium(III)] aceto-nitrile disolvate.

The title complexes, [Re2Br2(O2CC3H7)4], (1), and [Re2(O2CC3H7)4Cl2]·2CH3CN, (2), both exhibit paddlewheel structures with four carboxyl-ate ligands bridging two Re(III) atoms. The Re-Re distances are 2.2325 (2) and 2.2299 (3) Å, indicating quadruple bonds between the Re(III) atoms in each complex. Both complexes contain an inversion center at the mid-point of the Re-Re bond. The Re-Br bond [2.6712 (3) Å] in (1) is 0.1656 (6) Å longer than the Re-Cl distance [2.5056 (5) Å] of (2). In (2), the N atom of each co-crystallized aceto-nitrile solvent mol-ecule is nearly equidistant between and in close contact with two carboxyl-ate C atoms.

A one-dimensional chloride-bridged Pt(II)/Pt(IV) mixed-valence complex with a 4-[(4-hydroxyphenyl)diazenyl]benzenesulfonate counter-ion.

The title compound, catena-poly[[[bis(ethylenediamine-κ(2)N,N')platinum(II)]- μ-chlorido-[bis(ethylenediamine)platinum(IV)]-μ-chlorido] tetrakis{4-[(4-hydroxyphenyl)diazenyl]benzenesulfonate} dihydrate], {[Pt(II)Pt(IV)Cl2(C2H8N2)4](HOC6H4N=NC6H4SO3)4·2H2O}n, has a linear chain structure composed of square-planar [Pt(en)2](2+) (en is ethylenediamine) and elongated octahedral trans-[PtCl2(en)2](2+) cations stacked alternately, bridged by Cl atoms, along the b axis. The Pt atoms are located on an inversion centre, while the Cl atoms are disordered over two sites and form a zigzag ...Cl-Pt(IV)-Cl...Pt(II)... chain, with a Pt(IV)-Cl bond length of 2.3140 (14) Å, an interatomic Pt(II)...Cl distance of 3.5969 (15) Å and a Pt(IV)-Cl...Pt(II) angle of 170.66 (6)°. The structural parameter indicating the mixed-valence state of the Pt atom, expressed by δ = (Pt(IV)-Cl)/(Pt(II)...Cl), is 0.643.

Crystal structure of bis-(acetonyltri-phenyl-phospho-nium) tetra-chlorido-cobaltate(II).

The complex title salt, (C21H20OP)2[CoCl4], is the reaction product of CoCl2 with acetonyltri­phenyl­phospho­nium chloride in aceto­nitrile. In the anion, the CoII atom exhibits a typical tetra­hedral environment, with Co—Cl distances ranging from 2.2721 (6) to 2.2901 (6) Å, and with Cl—Co—Cl angles ranging from 106.12 (2) to 112.24 (2)°. The two phospho­nium cations likewise show the expected tetra­hedral configuration, with P—C distances ranging from 1.785 (2) to 1.8059 (18) Å and C—P—C angles ranging from 106.98 (8) to 112.85 (15)°. The mol­ecules inter­act in the lattice mainly through Coulombic and van der Waals forces because there is no particular polarity to the charges carried by the cations or anion. In the crystal, the cations and anions are arranged in sheets parallel to (001).

Crystal structure of di-chlorido-[2-(di-phenyl-phosphan-yl)-3,4,5,6-tetra-fluoro-benzene-1-thiol-ato-κ(2) P,S]gold(III).

The title compound, [Au(C18H10F4PS)Cl2], crystallizes as neutral mol­ecules, with the AuIII atom coordinated by two Cl atoms and by the P and S atoms of the bidentate phosphanyl thiol­ate ligand, in a slightly distorted square-planar environment. The mol­ecules are linked into centrosymmetric dimers via long axial Au—Cl bonds of 3.393 (4) Å. This axial Au—Cl distance is longer than is usually seen, although one other example has been given. Dimer formation may explain the unexpectedly low solubility of the compound in common polar solvents. There is also a separate inter­molecular Au—F contact of 3.561 (6) Å, but this distance seems too long to be regarded as a bond. Two putative C—H⋯F hydrogen bonds appear to link the dimers into sheets parallel to (110). There is a short inter­molecular F⋯F contact of 2.695 (10) Å between two dimers related by the twofold axis.

Metal–Halogen Secondary Bonding in a 2,5‐Dichlorohydroquinonate Cobalt(II) Complex: Insight into Substrate Coordination in the Chlorohydroquinone Dioxygenase PcpA

AbstractDespite the unprecedented selectivity of the hydroquinone ring‐cleaving dioxygenase PcpA for ortho‐chlorohydroquinones, there are no examples of an ortho‐chlorohydroquinone bound to a transition‐metal complex. Herein, the synthesis and characterization of (TpPh2Co)2(μ‐2,5‐dichlorohydroquinonate), for which TpPh2 is tris(3,5‐diphenylpyrazolyl)borate, were explored. The dianionic 2,5‐dichlorohydroquinonate bridges two (TpPh2Co) moieties and coordinates each cobalt(II) center through the oxygen and chlorine atoms of the chlorohydroquinone. The Co–Cl distance of 2.778 Å shows the characteristics of a metal–halogen secondary bond, as we previously showed in ortho‐halophenolate complexes. This compound represents the first example of metal–halogen secondary bonding with a halohydroquinone and, thus, provides a potential structural model for selective substrate binding to the metal center in PcpA.

Crystal structure of a mononuclear Ru(II) complex with a back-to-back terpyridine ligand: [RuCl(bpy)(tpy-tpy)](.).

We report the structural characterization of [6',6''-bis-(pyridin-2-yl)-2,2':4',4'':2'',2'''-quaterpyridine](2,2'-bi-pyridine)-chlorido-ruthenium(II) hexa-fluorido-phosphate, [RuCl(C10H8N2)(C30H20N6)]PF6, which contains the bidentate ligand 2,2'-bi-pyridine (bpy) and the tridendate ligand 6',6''-bis-(pyridin-2-yl)-2,2':4',4'':2'',2'''-quaterpyridine (tpy-tpy). The [RuCl(bpy)(tpy-tpy)](+) monocation has a distorted octa-hedral geometry at the central Ru(II) ion due to the restricted bite angle [159.32 (16)°] of the tridendate ligand. The Ru-bound tpy and bpy moieties are nearly planar and essentially perpendicular to each other with a dihedral angle of 89.78 (11)° between the least-squares planes. The lengths of the two Ru-N bonds for bpy are 2.028 (4) and 2.075 (4) Å, with the shorter bond being opposite to Ru-Cl. For tpy-tpy, the mean Ru-N distance involving the outer N atoms trans to each other is 2.053 (8) Å, whereas the length of the much shorter bond involving the central N atom is 1.936 (4) Å. The Ru-Cl distance is 2.3982 (16) Å. The free uncoordinated moiety of tpy-tpy adopts a trans,trans conformation about the inter-annular C-C bonds, with adjacent pyridyl rings being only approximately coplanar. The crystal packing shows significant π-π stacking inter-actions based on tpy-tpy. The crystal structure reported here is the first for a tpy-tpy complex of ruthenium.

Crystal structure of rac-(3aR*,9aS*)-4,4,4-tri-chloro-1,2,3,3a,4,9a-hexa-hydro-4λ(5),9λ(4)-cyclo-penta-[4,5][1,3]tellurazolo[3,2-a]pyridine.

The title compound, C10H12Cl3NTe, crystallizes with two crystallographically independent mol­ecules (A and B) in the asymmetric unit. In each case, the coordination around the Te atom is distorted square-pyramidal, with the equatorial plane composed of the three Cl atoms and the C atom of the pyridinium ring. The Te atom is displaced from the mean-square plane by 0.1926 (7) and 0.1981 (8) Å, in mol­ecules A and B, respectivly, away from the apical C atom. The bond lengths from the Te atom to the two Cl atoms arranged trans to each other [2.5009 (7)/2.5145 (7) and 2.5184 (7)/2.5220 (8) Å in mol­ecules A and B, respectivly] are substan­ti­ally shorter than the third Te—Cl distance [2.8786 (7) and 2.8763 (7) Å in mol­ecules A and B, respectivly]. The 1,3-tellurazole ring is almost planar (r.m.s. deviations of 0.042 and 0.045 Å in mol­ecules A and B, respectivly). The cyclopentane rings in both molecules A and B adopt envelope conformations with the carbon atom opposed to the (Te)C—C(N) bond as the flap. In the crystal, mol­ecules form centrosymmetric 2 + 2 associates via Te⋯Cl inter­actions [3.3993 (7) and 3.2030 (7) Å]. As a result of these secondary inter­actions, the Te atom attains a strongly distorted 5 + 1 octa­hedral environment. Further, the 2 + 2 associates are bound by weak C—H⋯Cl hydrogen bonds into a three–dimensional framework.