Least-squares Plane Research Articles

Crystal structure of 6,7-di-chloro-4-oxo-4H-chromene-3-carbaldehyde.

In the title compound, C10H4Cl2O3, a dichlorinated 3-formyl­chromone, the non-H atoms of the 4H-chromene ring are essentially coplanar (r.m.s. = 0.0188 Å), with the largest deviation from the least-squares plane [0.043 (2) Å] being for the pyran C=O C atom. The α,β-unsaturated carbonyl O atom deviates from the least-square plane by 0.124 (2) Å. The dihedral angle between the chromone and formyl least-square planes is 6.76 (3)°. In the crystal, mol­ecules are linked through C—H⋯O hydrogen bonds between the translation-symmetry and inversion-symmetry equivalents to form tetrads, which are further assembled by stacking inter­actions [centroid–centroid distance between the benzene rings = 3.769 (2) Å]. van der Waals contacts are found between the Cl atoms at the 6-position and the Cl atoms at 7-position of the glide-reflection-symmetry equivalents [Cl⋯Cl = 3.4785 (16) Å, C—Cl⋯Cl = 160.23 (7)° and Cl⋯Cl—C = 122.59 (7)°].

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 di-bromido-bis-(1,3-dibenzyl-1,3-diazinan-2-one-κO)cobalt(II).

The unit cell of the title complex, [CoBr2(C18H20N2O)2], contains 1.5 formula units per asymmetric unit with one mol­ecule sitting on a general site and a second one halved by a crystallographic twofold rotation axis passing through the CoII cation. Both CoII atoms are coordinated in a distorted tetra­hedral manner by two Br− ligands and two O atoms of the pyrimidinone (OPyr) groups. The Br—Co—Br coordination angles are similar [115.46 (4) and 115.20 (5)°], while the O—Co—O angles differ slightly more [102.26 (18) and 98.1 (2)°]. Similarly, the Co—Br bond lengths are almost identical [2.3721 (9), 2.3757 (10) and 2.3809 (10) Å], with a larger difference between the Co—O bond lengths [1.929 (4), 1.926 (4) and 1.955 (4) Å]. The three independent OPyr groups present envelope conformations, with three C and two N atoms lying in well defined planes with maximum deviations from the least-squares planes of 0.047, 0.031 and 0.036 Å, and the external-most C atoms protruding by 0.654 (6), 0.643 (7) and 0.656 (6) Å out of the planes. The dihedral angles between the planar fractions of the OPyr planes are 50.5 (1)° for the nonsymmetric mol­ecule and 49.7 (1)° for the symmetric one. Non-covalent inter­actions are of the C—H⋯Br type and they are weak, hardly shorter than van der Waals radii, with an H⋯Br distance range of 3.00–3.04 Å. The inter­molecular inter­actions define chains parallel to [101].

Crystal structure of 1-benzyl-2-hy-droxy-5-oxopyrrolidin-3-yl acetate.

In the title compound, C13H15NO4, the oxopyrrolidin-3-yl ring has an envelope conformation, with the C atom bearing the acetate group being the flap. The acetate and phenyl groups are inclined with respect to the central ring, forming dihedral angles of 50.20 (12) and 87.40 (9)°, respectively, with the least-squares plane through the ring. The dihedral angle between the acetate group and the phenyl ring is 63.22 (8)°, indicating a twisted conformation in the mol­ecule. In the crystal, supra­molecular chains along the b axis are formed by (hy­droxy)O—H⋯O(ring carbon­yl) hydrogen bonds. The chains are consolidated into the three-dimensional architecture by C—H⋯O inter­actions.

Crystal structure of 4-oxo-4H-chromene-3-carb-oxy-lic acid.

In the title compound, C10H6O4, also known as 3-carb­oxy­chromone, the non-H atoms of the chromone ring are essentially coplanar (r.m.s. deviation = 0.0057 Å), with the maximum deviation from their least-squares plane [0.011 (2) Å] being for a pyran C atom. The dihedral angle between the fused ring and plane of the carb­oxy group is 3.06 (2)°. An intra­molecular hydrogen bond is formed between the ring carbonyl O atom and the carb­oxy O—H atom, closing an S(6) loop. In the crystal, mol­ecules are assembled by stacking inter­actions [centroid–centroid distance between the benzene and pyran rings = 3.844 (3) Å] and C—H⋯O hydrogen bonds, generating a three-dimensional network. Short contacts are also observed between the carb­oxy O and C atoms [C=O⋯C=O = 3.002 (3) Å].

Crystal structure of bis-[μ-bis-(di-phenyl-phosphanyl)methane-κ(2) P:P']digold(I) dichloride acetone monosolvate monohydrate.

In the title complex salt, [Au2{(C6H5)2PCH2P(C6H5)2}]Cl2·(CH3)2C=O·H2O, the dication forms an eight-membered {-PCPAu}2 ring with a transannular aurophilic inter-action [Au⋯Au = 2.9743 (2) Å]. The ring approximates a flattened boat conformation, with the two methyl-ene C atoms lying ca 0.58-0.59 Å above the least-squares plane defined by the Au2P4 atoms (r.m.s. deviation = 0.0849 Å). One Cl(-) anion functions as a weak bridge between the Au(I) atoms [Au⋯Cl = 2.9492 (13) and 2.9776 (12) Å]. The second Cl(-) anion forms two (water)O-H⋯Cl hydrogen bonds about a centre of inversion, forming a centrosymmetric eight-membered {⋯HOH⋯Cl}2 supra-molecular square. Globally, the dications and loosely associated Cl(-) anions assemble into layers lying parallel to the ac plane, being connected by C-H⋯Cl,π(phen-yl) inter-actions. The supra-molecular squares and solvent acetone mol-ecules are sandwiched in the inter-layer region, being connected to the layers on either side by C-H⋯Cl,O(acetone) inter-actions.

Crystal structure of 8-bromo-4-oxo-4H-chromene-3-carbaldehyde.

In the title compound, C10H5BrO3, a brominated 3-formyl­chromone, all atoms are essentially coplanar (r.m.s. = 0.0104 Å for the non-H atoms), with the largest deviation from the least-squares plane [0.028 (5) Å] being for one of the benzene C atoms. In the crystal, mol­ecules are linked through C—H⋯O hydrogen bonds, which are further assembled by face-to-face π–π stacking inter­actions [centroid–centroid distance between the pyran rings = 3.854 (4) Å]. Shorter contacts than the sum of van der Waals radii are observed between the Br and formyl O atoms [Br⋯O = 3.046 (4) Å, C—Br⋯O = 175.23 (18)° and Br⋯O—C = 132.6 (3)°], features that do indicate halogen bonding.

Crystal structure of ethyl 8-chloro-4-oxo-1,4-di-hydro-quinoline-3-carboxyl-ate.

In the title compound, C12H10ClNO3, the asymmetric unit comprises two independent mol­ecules, and the dihedral angle between the least-square planes of the quinoline ring systems of these mol­ecules is 73.30 (5)°. In the crystal, N—H⋯O hydrogen bonds between the independent mol­ecules lead to supra­molecular layers parallel to (-1-10); both N—H H atoms are bifurcated.

Crystal structure of 3-acetyl-4H-chromen-4-one.

In the title compound, C11H8O3, the fused-ring system is almost planar (r.m.s. deviation = 0.020 Å), with the largest deviation from the least-squares plane [0.0462 (17) Å] being for a pyran C atom. The dihedral angle between the plane of the fused-ring system and acetyl plane is 5.149 (16)°. In the crystal, the fused rings are linked by aromatic π–π stacking inter­actions [centroid–centroid distance between the benzene and pyran rings = 3.643 (6) Å] and C—H⋯O hydrogen bonds, generating a three-dimensional network.

Crystal structure of 6-bromo-7-fluoro-4-oxo-4H-chromene-3-carbaldehyde.

In the title compound, C10H4BrFO3, a brominated and fluorinated 3-formyl-chromone derivative, all atoms are essentially coplanar (r.m.s. deviation of 0.025 Å for the non-H atoms), with the largest deviation from the least-squares plane [0.050 (6) Å] being for a benzene-ring C atom. In the crystal, mol-ecules are linked through stacking inter-actions [centroid-centroid distance between the benzene and pyran rings = 3.912 (4) Å], C-H⋯O hydrogen bonds and short C⋯O contacts [2.865 (7) Å]. Unsymmetrical halogen⋯halogen inter-actions between the bromine and fluorine atoms [Br⋯F = 3.116 (4) Å, C-Br⋯F = 151.8 (2), C-F⋯Br = 154.1 (4)°] are also formed, giving a meandering two-dimensional network propagating in the (041) plane. A comparison with related structures is made and the various types of weak inter-actions are ranked in importance.

Crystal structure of ethyl 6-chloro-methyl-2-oxo-4-(2,3,4-tri-meth-oxy-phen-yl)-1,2,3,4-tetra-hydro-pyrimidine-5-carboxyl-ate.

In the title compound, C17H21ClN2O6, the di-hydro-pyrimidine ring adopts a flattened envelope conformation, with the sp (3)-hybridized C atom forming the flap. The dihedral angle between the least-squares planes of the benzene and di-hydro-pyrimidine rings is 88.09 (6)°. An intra-molecular C-H⋯O hydrogen bond generates an S(6) ring. In the crystal, mol-ecules are linked via pairs of N-H⋯O hydrogen bonds, forming inversion dimers with an R 2 (2)(8) ring motif, and the dimers are linked via further pairs of N-H⋯O hydrogen bonds, forming R 2 (2)(14) rings and chains of mol-ecules along [111]. Pairs of inversion-related chains are linked via weak C-H⋯π inter-actions.

Crystal structure of 1-[(6-chloro-pyridin-3-yl)sulfon-yl]-1,2,3,4-tetra-hydro-quinoline.

The tetra-hydro-pyridine ring of the quinoline system in the title compound, C14H13ClN2O2S, adopts a half-chair conformation with the bond-angle sum at the N atom being 350.0°. The dihedral angle between the least-squares planes of the two aromatic rings is 50.13 (11)°. In the crystal, inversion dimers linked by pairs of C-H⋯O hydrogen bonds generate R 2 (2)(10) loops. Additional inter-molecular C-H⋯O hydrogen bonds generate C(7) chains along [100].

Crystal structure of N,N'-[(thio-phene-2,5-di-yl)bis-(methanylyl-idene)]di-p-toluidine.

The title compound, C20H18N2S, was synthesized by the condensation reaction between p-tolu­idine and thio­phene-2,5-dicarboxaldehye in refluxing toluene with p-toluene­sulfonic acid added as catalyst. The mol­ecule lies on a twofold rotation axis and adopts an E orientation with respect to the azomethine bonds. The dihedral angle between the unqiue benzene ring and the least-squares plane [maximum deviation = 0.0145 (14) Å] containing the azomethine and thio­phene groups is 32.31 (6)°.

Crystal structure of (4-fluoro-phenyl-κC (1))iodido-(N,N,N',N'-tetra-methyl-ethylenedi-amine-κ(2) N,N')palladium(II).

In the title compound, [Pd(C6H4F)I(C6H16N2)], the PdII atom is coordinated by two N atoms from the N,N,N′,N′-tetra­methyl­ethylenedi­amine ligand, a C atom of the 4-fluoro­phenyl group and an iodide ligand in a distorted square-planar geometry, with an average deviation from the least-squares plane through the ligand donor atoms of 0.0159 (2) Å. The angles about the PdII atom range from 83.35 (16) to 178.59 (11)°. In the crystal, weak C—H⋯F and C—H⋯I hydrogen bonds link the mol­ecules into sheets in the bc plane.

Geometric perturbations in multiheaded papillary tip positions associated with acute ovine ischemic mitral regurgitation

BackgroundNovel surgical approaches are focusing on the “ventricular disease” of ischemic mitral regurgitation (IMR), to correct altered papillary muscle (PM) tip positions (apical displacement) and ameliorate leaflet tethering. Due to the anatomic complexity of the subvalvular apparatus, however, the precise geometric perturbations of the multiheaded PM tips associated with IMR remain uncharacterized. MethodsIn 6 adult sheep, we implanted 3 markers on each PM. To specifically identify distinct PM tips, 1 marker was placed on the PM origin of the dominant chord to the anterior, posterior, and commissural leaflets. Nine markers were placed on the edge of the posterior mitral leaflet, and 5 on the edge of the anterior mitral leaflet. Eight markers were sewn around the mitral annulus. Animals were studied immediately postoperatively, with biplane videofluoroscopy and transesophageal echocardiography, before and during acute snare occlusion of the proximal left circumflex coronary artery, to induce IMR. Papillary muscle tip and leaflet edge geometry was expressed as the orthogonal distance of each respective marker to the least-squares mitral annulus plane at end-systole. In addition, the distance from each PM tip marker to the mitral annulus “saddle horn” was calculated. ResultsAcute left circumflex occlusion significantly increased mitral regurgitation from a baseline of 0.7 ± 0.3 to 2.5 ± 0.5 (P < .05). The IMR was associated with posterior leaflet restriction near the central leaflet edge, with simultaneous prolapse of both leaflets near the posterior commissure. No apical displacement of PM tips was observed during IMR, although the posterior PM moved farther away from the midseptal annulus. ConclusionsDuring acute ischemia, no apical displacement of any PM tip was observed. Posterior PM movement away from the annular saddle horn, and toward the annulus, was associated with IMR and leaflet prolapse near the posterior commissure, and with restriction near the valve center. These data may help guide development of surgical interventions aimed at PM repositioning.

Crystal structure of (1,3-di-tert-butyl-η(5)-cyclo-penta-dien-yl)tri-methyl-hafnium(IV).

The mol­ecule of the title organometallic hafnium(IV) com­pound, [Hf(CH3)3(C13H21)] or [HfMe3(η5-C5H3-1,3-tBu2)], adopts the classical three-legged piano-stool geometry for mono­cyclo­penta­dienylhafnium(IV) derivatives with the three methyl groups bonded to the Hf(IV) atom at the legs. The C atoms of the two tert-butyl group bonded to the cyclo­penta­dienyl (Cp) ring are 0.132 (5) and 0.154 (6) Å above the Cp least-squares plane. There are no significant inter­molecular inter­actions present between the mol­ecules in the crystal structure.

Crystal structure of 2-(1-methyl-eth-yl)-1,3-thia-zolo[4,5-b]pyridine.

In the title mol­ecule, C9H10N2S, one of the methyl groups is almost co-planar with the thia­zolo­pyridine rings with a deviation of 0.311 (3) Å from the least-squares plane of the thia­zolo­pyridine group. In the crystal, weak C—H⋯N hydrogen-bonding inter­actions lead to the formation of chains along [011].

Crystal structure of 2-(3-bromo-phen-yl)-1,3-di-thiane.

In the title compound, C10H11BrS2, the 1,3-di­thiane ring has a chair conformation with the 1,4-disposed C atoms being above and below the remaining four atoms. The bromo­benzene ring occupies an equatorial position and forms a dihedral angle of 86.38 (12)° with the least-squares plane through the 1,3-di­thiane ring. Thus, to a first approximation the mol­ecule has mirror symmetry with the mirror containing the bromo­benzene ring and the 1,4-disposed C atoms of the 1,3-di­thiane ring. In the crystal, mol­ecules associate via weak methyl­ene–bromo­benzene C—H⋯π and π–π [Cg⋯Cg = 3.7770 (14) Å for centrosymmetrically related bromo­benzene rings] inter­actions, forming supra­molecular layers parallel to [10-1]; these stack with no specific inter­molecular inter­actions between them.

Crystal structure of 5-(1,3-di-thian-2-yl)-2H-1,3-benzodioxole.

In the title compound, C11H12O2S2, two independent but virtually superimposable mol­ecules, A and B, comprise the asymmetric unit. In each mol­ecule, the 1,3-di­thiane ring has a chair conformation with the 1,4-disposed C atoms being above and below the plane through the remaining four atoms. The substituted benzene ring occupies an equatorial position in each case and forms dihedral angles of 85.62 (9) (mol­ecule A) and 85.69 (8)° (mol­ecule B) with the least-squares plane through the 1,3-di­thiane ring. The difference between the mol­ecules rests in the conformation of the five-membered 1,3-dioxole ring which is an envelope in mol­ecule A (the methyl­ene C atom is the flap) and almost planar in mol­ecule B (r.m.s. deviation = 0.046 Å). In the crystal, mol­ecules of A self-associate into supra­molecular zigzag chains (generated by glide symmetry along the c axis) via methyl­ene C—H⋯π inter­actions. Mol­ecules of B form similar chains. The chains pack with no specific directional inter­molecular inter­actions between them.

Crystal structure of 2-(3-nitro-phen-yl)-1,3-di-thiane.

In the title compound, C10H11NO2S2, the 1,3-di­thiane ring has a chair conformation with the 1,4-disposed C atoms being above and below the remaining four atoms. The nitro­benzene substituent occupies an equatorial position and forms a dihedral angle of 88.28 (5)° with the least-squares plane through the 1,3-di­thiane ring. The nitro group is twisted out of the plane of the benzene ring to which it is connected, forming a dihedral angle of 10.12 (3)°. In the crystal, mol­ecules aggregate into supra­molecular zigzag chains (glide symmetry along the c axis) via nitro–benzene N—O⋯π [N—O⋯Cg(benzene) = 3.4279 (18) Å and angle at O = 93.95 (11)°] inter­actions. The chains pack with no specific inter­molecular inter­actions between them.