Ring Centroid Distance Research Articles

N′-[(E)-2-Methoxybenzylidene]pyrazine-2-carbohydrazide

In the title compound, C13H12N4O2, all the non-H atoms lie on a crystallographic mirror plane and an intra­molecular N—H⋯N hydrogen bond generates an S(5) ring; the conformation about the imine bond [1.280 (3) Å] is E. In the crystal, mol­ecules assemble into a two-dimensional array via C—H⋯O(carbon­yl) and C—H⋯N(pyrazine) contacts. Layers stack along the b-axis direction via weak π–π inter­actions between pyrazine rings [ring centroid distance = 3.8028 (8) Å].

Tricarbonyl[N,N′,N′′-tris(2,6-diisopropylphenyl)guanidine]molybdenum(0)

In the title compound, [Mo(C37H53N3)(CO)3], the Mo atom to ring-centroid distance in the η6-coordinated tricarbonyl­molybdenum group is 1.958 (1) Å. The three C O groups are pseudo-octa­hedrally disposed with C—Mo—C angles ranging from 80.7 (1) to 87.4 (1)°. The two uncoordinated 2,6-diisopropyl­phenyl-substituted benzene rings form dihedral angles of 75.96 (8) and 78.01 (9)° with the mean plane of the guanidine group. The coordinated benzene ring is in a slight sofa conformation with the N-substituted C atom and the bonded N atom dispaced by 0.090 (3) and 0.458 (4) Å, respectively, from the mean plane of the remaining ring atoms. In the crystal, despite there being two N—H donor groups, no conventional hydrogen bonds are present. This may be because of the steric effects of the bulky diisopropyl­phenyl groups.

Bis(N-isopropyl-N-methyldithiocarbamato-κ2S,S′)(1,10-phenanthroline-κ2N,N′)zinc

The ZnII atom in the title compound, [Zn(C5H10NS2)2(C12H8N2)], exists in a distorted cis-octa­hedral N2S4 donor set defined by two chelating dithio­carbamate anions as well as a 1,10-phenanthroline ligand. Each of the ligands coordinates in a symmetric mode. The crystal packing is stabilized by weak C—H⋯S, C—H⋯π(ZnS2C) and π–π [ring centroid distance between centrosymmetrically related pyridyl rings = 3.5955 (13) Å] inter­actions.

(2,2′-Bipyridine-κ2N,N′)bis(N-isopropyl-N-methyldithiocarbamato-κ2S,S′)cadmium

The CdII atom in the title compound, [Cd(C5H10NS2)2(C10H8N2)], exists in an N2S4 donor set defined by two chelating dithio­carbamate anions as well as a 2,2′-bipyridine ligand. The coordination geometry approximates a trigonal prism. The crystal packing features weak C—H⋯S inter­actions, leading to linear supra­molecular chains along the a axis. The primary connections between these are by π–π stacking inter­actions [ring centroid distance between centrosymmetrically related pyridyl rings = 3.7455 (10) Å]. Overall, the crystal structure may be described as comprising double layers of mol­ecules that stack along the b axis.

(Dodecafluorosubphthalocyaninato)(4-methylphenolato)boron(III)

In the title compound, C31H7BF12N6O, mol­ecules are arranged into one-dimensional columns with an inter­molecular B⋯B distance of 5.3176 (8) Å. Bowl-shaped mol­ecules are arranged within the columns in a concave bowl-to-ligand arrangement separated by a ring centroid distance of 3.532 (2) Å between the benzene ring of the 4-methyl­phen­oxy ligand and one of the three five-membered rings of a symmetry-related mol­ecule.

N-(4-Bromo-phen-yl)pyrazine-2-carbox-amide.

The mol­ecule of the title compound, C11H8BrN3O, is close to planar (r.m.s. deviation of all 16 non-H atoms = 0.103 Å), a conformation stabilized by an intra­molecular N—H⋯N hydrogen bond, which generates an S(5) ring. In the crystal structure, supra­molecular chains mediated by C—H⋯O contacts (along a) are linked into a double layer via N⋯Br halogen bonds [3.207 (5) Å] and C—Br⋯π inter­actions [Br⋯ring centroid(pyrazine) = 3.446 (3) Å]. The layers stack along the b axis via weak π–π inter­actions [ring centroid(pyrazine)⋯ring centroid(benzene) distance = 3.803 (4) Å].

Benzoic acid–2,9-dimethylphenanthroline (1/1)

The constituents of the title 1:1 co-crystal, C7H6O2·C14H12N2, are connected into dimeric aggregates by a bifurcated O—H⋯N hydrogen bond; the hydroxyl-H atom is hydrogen bonded to the two N atoms of the 2,9-dimethyl­phenanthroline. The hydrogen-bonded residues are almost orthogonal to each other [dihedral angle = 78.56 (7) °]. In the crystal packing, the aggregates are assembled into layers in the bc plane by π⋯π inter­actions [ring centroid⋯ring centroid distance = 3.5577 (16) Å] involving the pyridyl rings, and C–H⋯π contacts involving the phenanthroline-H atom and the phenyl ring of the acid.

7-Chloro-4-[(E)-2-(4-methoxy-benzyl-idene)hydrazin-1-yl]quinoline monohydrate.

The organic mol­ecule in the title hydrate, C17H14ClN3O·H2O, has a small but significant twist from planarity, as seen in the dihedral angle of 12.10 (17)° between the quinoline and benzene rings. The conformation about the C=N bond is E. Chains along the b axis are formed in the crystal structure aided by water–quinoline O—H⋯N (× 2) and hydrazone–water N—H⋯O hydrogen bonds. Layers of these chains stack along the a axis via C—H⋯π and π–π inter­actions [ring centroid–ring centroid distance = 3.674 (2) Å]. C—H⋯O inter­actions are also present.

The effect of pressure on the crystal structure of [Gd(PhCOO)3(DMF)]n to 3.7 GPa and the transition to a second phase at 5.0 GPa

The effect of pressure on the crystal structure of the coordination polymer [Gd(PhCOO)(3)(DMF)](n) has been studied to 5.0 GPa. At ambient pressure the structure is tetragonal (space group P4(2)/n) with the polymers extending along the c-direction of the unit cell; successive Gd atoms are alternately bridged by four benzoates and by two benzoates; the coordination spheres of the metal atoms are completed by DMF ligands. This results in two different Gd...Gd repeats, measuring 3.8953(3) and 5.3062(3) A, respectively. The polymer chains interact with each other via dispersion interactions, including a number of CH...pi contacts to phenyl rings in which the H...ring-centroid distances are 3.19 to 3.28 A. Up to 3.7 GPa the crystal remains in a compressed form of its ambient-pressure phase. The a-axis shortens by 7.7%, and the c-axis by 2.9%, the difference reflecting the greater ease of compression along the crystallographic directions mediated by weak intermolecular interactions. At ambient pressure the Gd-O distances span 2.290(2)-2.559(2) A, with an average of 2.39(3) A. At 3.7 GPa the corresponding parameters are 2.259(3) to 2.509(4) and 2.36(3) A. The Gd...Gd distances shortened by 0.0467(4) and 0.1851(4) A, and the CH...pi distances span the range 2.76-2.90 A. During compression a number of H...H contacts develop, the shortest measuring 1.84 A at 3.7 GPa. On increasing the pressure to 5.0 GPa a phase transition occurred in which the shortest H...H contact is relieved by conversion of an edge-to-edge phenyl-phenyl contact into a pi...pi stacking interaction. The new phase is also tetragonal, space group P4, the inversion symmetry present in phase-I being lost in phase-II. The phase transition allows more efficient packing of ligands, and while the a-axis decreases in length the c-axis increases. This leads to Gd...Gd distances of 3.8373(4) and 5.3694(4) A, the latter being longer than at ambient pressure. Gd-O distances at 5.0 GPa span the range 2.265(5) to 2.516(5) A, with a mean of 2.36(2) A.

Aqua(6,6′-oxydipicolinato-κ2O,N,N′,O′)copper(II)

In the title complex, [Cu(C12H6N2O5)(H2O)], the CuII ion is in a slightly distorted square-pyramidal coordination environment with two N and two O atoms from a 6,6′-oxydipicolinate ligand occupying the basal plane and a water ligand in the apical site. The dihedral angle between the two pyridine rings is 5.51 (6)°. In the crystal structure, inter­molecular O—H⋯O hydrogen bonds link mol­ecules into a two-dimensional network. In addition, weak inter­molecular C—H⋯O and C=O(lone pair)⋯π(ring) inter­actions, with O⋯ring-centroid distances of 3.697 (4) and 3.094 (4) Å, provide additional stabilization.

1-Bromo-1′-(diphenylthiophosphoryl)ferrocene

The title compound, [Fe(C5H4Br)(C17H14PS)], crystallizes with two practically undistiguishable mol­ecules in the asymmetric unit, which are related by a non-space-group inversion. The ferrocene-1,1′-diyl units exhibit a regular geometry with negligible tilting and balanced Fe–ring centroid distances, and with the attached substituents assuming conformations close to ideal synclinal eclipsed.

(E)-1-Ferrocenyl-3-(3-nitro-phen-yl)prop-2-en-1-one.

In the title compound, [Fe(C5H5)(C14H10NO3)], one cyclo­penta­diene ring is substituted and one is unsubstituted. The two rings are almost parallel and are eclipsed and ordered. The conjugated substituent is slightly twisted with respect to the cyclo­penta­diene ring. The crystal structure contains four inter­molecular C—H⋯O hydrogen-bonds in the range 3.324 (3)–3.539 (3) Å and one π(aryl ring)–π (Cp ring) stacking inter­action with a ring–centroid distance of 3.894 (2) Å.

(2,2-Bipyridyl)bis(η5-pentamethylcyclopentadienyl)strontium(II)

In the title compound, [Sr(C10H15)2(C10H8N2)], the Sr—N distances are 2.624 (3) and 2.676 (3) Å, the Sr⋯Cp ring centroid distances are 2.571 and 2.561 Å and the N—C—C—N torsion angle in the bipyridine ligand is −2.2 (4)°. Inter­estingly, the bipyridine ligand is tilted. The angle between the plane defined by the Sr atom and the two bipyridyl N atoms and the plane defined by the 12 atoms of the bipyridine ligand is 10.7 (1)°.

Ethyl anthracene-9-carboxylate

In the title compound, C17H14O2, the COO group and the anthracene fragment form a dihedral angle of 76.00 (19)°. The torsion angle around the O—Csp 3 bond of the ester group is 108.52 (18)°. The crystal structure is stabilized by C—H⋯O inter­actions and edge-to-face arene inter­actions with C—H⋯(ring centroid) distances in the range 2.75–2.84 Å.

Ethyl 4-(2-bromomethyl-5,5-dimethyl-1,3-dioxan-2-yl)-5-methylisoxazole-3-carboxylate

In the structure of the title compound, C14H20BrNO5, at 90 (2) K, the isoxazole is an axial substituent of the chair conformation dimethyl­dioxanyl ring. There is an anti­parallel arrangement of the isoxazole rings with an oxygen to ring centroid distance of 3.402 (6) A.

Experimental and calculated structural parameters of 4-(2-methoxycarbonyl-ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylic acid benzyl ester

Crystal structure of 4-(2-methoxycarbonyl-ethyl)-3,5-dimethyl-1 H-pyrrole-2-carboxylic acid benzyl ester has been solved by X-ray diffraction. The crystals are triclinic, space group P 1 ¯ , with a=5.4435(18) Å, b=12.248(2) Å, c=13.6769(15) Å, α=70.274(12)°, β=81.630(15)°, γ=77.60(2)°, Z=2 and R=0.0519. The molecules are strongly linked in dimers by hydrogen bonds, forming rings with R 2 2 ( 10 ) as the graph descriptor. The pyrrolic ring, slightly distorted from the C 2 v symmetry, is almost planar. This plane makes an angle of 75.5(1)° with the L.S. plane containing the methoxy-carbonyl group and an angle of 13.6(1)° with the L.S. plane containing the benzyl group. The internal cohesion of the crystal is supported by three C–H…π intermolecular interactions, with H…Cg (ring centroid) distances ranging from 3.060 to 3.377 Å. Several calculations were performed for the dimer such as density functional theory with a hybrid functional B3LYP, semi-empirical self-consistent field (AM1 and PM3) and self-consistent field molecular orbital Hartree–Fock (SCF-MO HF) method. The latter calculation was repeated for the isolated molecule. In all cases the minimum of the energy is achieved with the substituents assuming a more perpendicular position to the central aromatic ring than is experimentally observed.

Difluoro(η5,η5-propane-2,2-diyldicyclopentadienyl)titanium(IV)

In the title compound, [Ti(C13H14)F2], the coordination polyhedron around the Ti atom is a distorted tetra­hedron defined by the centroids of the cyclo­penta­dien­yl rings and the two F atoms. The Ti–ring centroid (Cg) distances are 2.0558 (7) and 2.0567 (8) Å. The presence of a short carbon bridge linking the cyclo­penta­dien­yl rings constrains the Cg—Ti—Cg angle to a value of 121.50 (3)°.

{(η5,κN)-[(tert-Butylamido)dimethylsilyl]cyclopentadienyl}dichlorotitanium(IV)

The crystal structure of the title compound, [Ti(C11H19NSi)Cl2], has been determined as part of a broad investigation of half-sandwich titanium complexes. Titanium has a pseudo-tetrahedral coordination formed by two Cl atoms [Ti—Cl = 2.2719 (4) and 2.2730 (4) A], the N atom of the N-tert-butyl group [Ti—N = 1.9094 (12) A] and the silyl-substituted Cp ligand [metal–Cp ring centroid distance = 2.0185 (9) A]. The tert-butyl group was found to be disordered.

Ansa-[(tert-Butylamino)(isodicyclopentadienyl)dimethylsilane]Zr(NMe2)2 prepared by an amine-elimination reaction.

An amine-elimination reaction was used to obtain the title compound, i.e. (N-tert-butyl-N-[[(1,2,3,3a,7a-eta)-4,5,6,7-tetrahydro-4,7-methano-1H-inden-2-yl]dimethylsilyl]amido-kappaN)bis(N-methylmethanaminato-kappaN)zirconium(IV) or [isodiCpSiMe(2)N-tert-butyl]Zr(NMe(2))(2) (Cp is cyclopentadienyl), [Zr(C(16)H(25)NSi)(C(2)H(6)N)(2)], in very good yield. Treatment of isodiCpHSiMe(2)NH-tert-butyl with Zr(NMe(2))(4) leads to the formation of a yellow solid that can be purified by sublimation. The single-crystal structure of the product shows the exo complexation of the isodicyclopentadienyl ligand to the Zr atom. The Cp portion of this ligand is bonded to the Zr atom in a eta(5) manner, with a Zr-Cg (Cg is the ring centroid) distance of 2.2352 (10) A. The isodiCpSiMe(2)N-tert-butyl ligand has a constrained geometry, which is exhibited by the small angle of 95.55 (10) degrees for N-Si-C(Cp).

Synthesis and structure of tris(alkyl- and silyl-tetramethylcyclopentadienyl) complexes of lanthanum.

In efforts to make sterically crowded tris(peralkylcyclopentadienyl) complexes of lanthanum for the exploration of sterically induced reduction chemistry with a diamagnetic system, the synthesis of (C(5)Me(4)R)(3)La complexes has been pursued with R = Me, Et, (i)Pr, and SiMe(3). The complexes were synthesized in four steps: reaction of LaCl(3) with KC(5)Me(4)R to form (C(5)Me(4)R)(2)LaCl(2)K(THF)(2), addition of allylmagnesium chloride to make (C(5)Me(4)R)(2)La(C(3)H(5)), protonolysis with Et(3)NHBPh(4) to make [(C(5)Me(4)R)(2)La][BPh(4)], and finally the replacement of BPh(4)(-) with C(5)Me(4)R(-) using KC(5)Me(4)R to make (C(5)Me(4)R)(3)La. X-ray crystallographic data were obtainable on the (C(5)Me(4)R)(3)La complexes for R = Me, Et, (i)Pr, and SiMe(3). In each complex, the three C(5)Me(4)R ring centroids define a trigonal planar geometry around La. The average La-(ring centroid) distances are 2.64, 2.65, 2.66, and 2.69 A for the Me, Et, (i)Pr, and SiMe(3) structures, respectively, with La-C distances ranging from 2.857 (3) to 3.029 (2) A. Despite the steric crowding, ligand exchange can be observed by NMR spectroscopy.