Pentacoordinated Molecules. 107. Axial Preference of a Phenyl Group in a Trigonal Bipyramidal Tetraoxyphosphorane. A Unique Five-Coordinated Geometry

1995 ◽  
Vol 34 (18) ◽  
pp. 4525-4526 ◽  
Author(s):  
Natalya V. Timosheva ◽  
T. K. Prakasha ◽  
A. Chandrasekaran ◽  
Roberta O. Day ◽  
Robert R. Holmes
1995 ◽  
Vol 48 (4) ◽  
pp. 741 ◽  
Author(s):  
GB Deacon ◽  
TC Feng ◽  
BW Skelton ◽  
AH White

The X-ray crystal structure of Nd (Odpp)3 ( Odpp- = 2,6-diphenylphenolate), obtained by sublimation of Nd ( Odpp )3( thf )2 ( thf = tetrahydrofuran ) [triclinic, Pī , a 15.835(5), b 13.499(10), c 10.955(11) Ǻ, α 116.25(7), β 92.87(7), γ 101.66(6)°, V 2031 Ǻ3, Z2, No 5726 'observed' data (I > 3σ(I)) refined to conventional R 0.047 shows a near triangular array of oxygens surrounding neodymium { Nd -O} 2.169 Ǻ, ∑ O- Nd -O 353.2° with additional, intramolecular Nd-η6-Ph chelate interactions { Nd -C} 3.046 Ǻ and Nd-η1-Ph ( Nd -C 2.964(7)Ǻ). There is a pseudotrigonal bipyramidal arrangement of the oxygens, the centroid of the η6-Ph, and the η1-carbon. The complex Nd ( Odpp )3( thf ), obtained by crystallization of Nd ( Odpp )3( thf )2 from toluene (monoclinic, P21/c, a 12.213(4), b 21.447(4), c 17.744Ǻ, β 104.25(2)°, V 4505 Ǻ3, Z 4, R 0.042 for No 8014) also has pseudotrigonal bipyramidal stereochemistry, with a triangular equatorial array of aryl oxide oxygens { Nd -O} 2.193 Ǻ; ∑ O- Nd -O 358.7°, an apical thf oxygen (Nd -O 2.446(3)Ǻ), and an apical intramolecular chelating phenyl group. As the last has three Nd -C contacts (3.094(5), 3.144(5), 3.010(5)Ǻ) significantly shorter than the other three (3.300(5), 3.427(5), 3.377(5)Ǻ), an η3-Ph-Nd interaction seems likely. For [ Nd ( Odpp )3( thf )2].2( thf ), obtained by crystallization from tetrahydrofuran without drying of the crystals, the X-ray structure (monoclinic, P21, a 10.230(2), b 21.919(5), c 13.411(4) Ǻ, β 101.15(2)°, V 2950 A3, Z2, R 0.058 for No 3237) reveals a distorted trigonal bipyramidal arrangement of three aryl oxide oxygens (two equatorial 2.208(9), 2.16(1) Ǻ; one axial 2.203(9) Ǻ) and two thf oxygens (one equatorial 2.44(1) Ǻ; one axial (significantly distant) 2.62(1) Ǻ). The X-ray structure of [La( Odpp )3( thf )2].2( thf ) shows it to be isostructural with the neodymium analogue.


2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Hemant K. Sharma ◽  
Alejandro J. Metta-Magaña ◽  
Laura I. Saucedo ◽  
Marcela López-Cardoso ◽  
Keith H. Pannell

Abstract The tetrahedral geometry of organolead(IV) compounds can be readily transformed by using an organic ligand containing a dangling-arm oxygen functionality. The acidity of the Pb center results in so-called secondary bonding between O and Pb thereby pushing the geometry at Pb toward a trigonal bipyramidal (tbp) structure. Replacing a phenyl group by a chlorine atom dramatically enhances this phenomenon. Thus for (o-methoxybenzyl) triphenyllead (4), and (o-methoxybenzyl)diphenyllead chloride (5), the Pb–O internuclear distances are 3.362(4) and 2.845(3) Å, respectively; 83% (4) and 70% (5) of the sum of the van der Waals Pb and O radii. Within the group 14 element congeners the structural analysis of the (o-methoxybenzyl)triphenylE compounds, E = Si, Ge, Sn, and now Pb, demonstrates the relative acidities of E are Si < Ge < Sn < Pb.


1997 ◽  
Vol 52 (2) ◽  
pp. 193-198 ◽  
Author(s):  
Frank Kunkel ◽  
Klaus Harms ◽  
Hak-Chul Kang ◽  
Werner Massa ◽  
Kurt Dehnicke

Abstract Triphenylantimony reacts with S3N2Cl2 in dichloromethane solution to give yellow crystals of the cyclostibathiazene derivative [xxx], As a by-product orange single crystals of [(Ph3SbCl2)2·S4N4] were isolated, in which the molecular compounds Ph3SbCl2 and S4N4 only form van der Waals contacts with one another. Both compounds are characterized by crystal structure determinations. [xxx]: Space group P21/n, Z = 4; lattice dimensions at -80°C: a = 759.4(1), b = 1448.5(3); c = 1557.6(2) pm; β = 91.09(1)°, R = 0.026. The complex has a molecular structure in which the Sb atom is coordinate in a distorted trigonal-bipyramidal fashion with one phenyl group and one of the nitrogen atoms of the planar [xxx] ring in the apical positions.[(Ph3SbCL)2·S4N4]: Space group C2/c, Z = 8 ; lattice dimensions at -60°C: a = 1549.3(1), b = 1017.7(1), c = 2623.9(1) pm, β = 105.56(2)°, R = 0.050.


2009 ◽  
Vol 65 (6) ◽  
pp. m656-m657 ◽  
Author(s):  
Li Quan ◽  
Handong Yin ◽  
Liansheng Cui ◽  
Minglei Yang ◽  
Daqi Wang

The title complex, [Sb(C6H5)3(C8H4F3O2)2], is located on a twofold axis defined by the metal center and two C atoms of a coordinated phenyl group. The environment of the Sb atom approximates a trigonal-bipyramidal geometry, with the axial positions occupied by the O atoms of symmetry-related 4-(trifluoromethyl)benzoate ligands. In this ligand, the CF3group is disordered by rotation about the C—C bond and the F atoms are distributed over two sets of sites with occupancies of 0.62 (3) and 0.38 (3). In the crystal, molecules are assembled in a three-dimensional framework through weak C—H...O hydrogen bonds.


2007 ◽  
Vol 63 (11) ◽  
pp. m2689-m2689 ◽  
Author(s):  
Yan Dong

The Sn atom of the title compound, [Sn(C6H5)2(C12H12ClNO3)], is in a distorted SnNC2O2 trigonal–bipyramidal geometry and forms five- and six-membered chelate rings with the tridentate ligand. One phenyl group is disordered over two positions with occupancy factors 0.58 (3):0.42 (3).


2019 ◽  
Author(s):  
Min Zhou ◽  
Jet Tsien ◽  
Tian Qin

<p>Herein we report a sulfur (IV) mediated cross-coupling for facile synthesis of heteroaromatic substrates. Addition of heteroaryl nucleophiles onto a simple, readily-accessible alkyl sulfinyl (IV) chloride allows formation of a trigonal bipyramidal sulfurane intermediate. Reductive elimination therefrom provides bis-heteroaryl products in a practical and efficient fashion. <br></p>


Author(s):  
Katharigatta N. Venugopala ◽  
Christophe Tratrat ◽  
Melendhran Pillay ◽  
Pran Kishore Deb ◽  
Deepak Chopra ◽  
...  

Background: Tuberculosis remains one of the most deadly infectious diseases worldwide due to the emergence of multi-drug resistance (MDR) and extensively drug resistance (XDR) strains of Mycobacterium tuberculosis (MTB). Materials and Methods: Herein, the screening of a total of eight symmetrical 1,4-dihydropyridine (1,4-DHP) derivatives (4a-4h) was carried out for whole-cell anti-TB activity against the susceptible H37Rv and MDR strains of MTB. Results and Discussion: Most of the compounds exhibited moderate to excellent activity against the susceptible H37Rv. Moreover, the most promising compound 4f (against H37Rv) having para-trifluoromethyl phenyl group at 4-position and bis para-methoxy benzyl ester group at 3- and 5-positions of 1,4-dihydropyridine pharmacophore, exhibited no toxicity, but demonstrated weak activity against MTB strains resistant to isoniazid and rifampicin. In light of the inhibitory profile of the title compounds, enoyl-acyl carrier protein reductase (InhA) appeared to be the appropriate molecular target. Docking study of these derivatives against InhA receptor revealed favorable binding interactions. Further, in silico predicted ADME properties of these compounds 4a-4h were found to be in the acceptable ranges including satisfactory Lipinski’s rule of five, thereby indicating their potential as drug-like molecules. Conclusion: In particular, the 1,4-DHP derivative 4f can be considered as an attractive lead molecule for further exploration and development of more potent anti-TB agents as InhA inhibitors.


1983 ◽  
Vol 48 (2) ◽  
pp. 586-595 ◽  
Author(s):  
Alexander Perjéssy ◽  
Pavol Hrnčiar ◽  
Ján Šraga

The wave numbers of the fundamental C=O and C=C stretching vibrations, as well as that of the first overtone of C=O stretching vibration of 2-(3-, and 4-substituted phenylmethylene)-1,3-cycloheptanediones and 1,3-cycloheptanedione were measured in tetrachloromethane and chloroform. The spectral data were correlated with σ+ constants of substituents attached to phenyl group and with wave number shifts of the C=O stretching vibration of substituted acetophenones. The slope of the linear dependence ν vs ν+ of the C=C stretching vibration of the ethylenic group was found to be more than two times higher than that of the analogous correlation of the C=O stretching vibration. Positive values of anharmonicity for asymmetric C=O stretching vibration can be considered as an evidence of the vibrational coupling in a cyclic 1,3-dicarbonyl system similarly, as with derivatives of 1,3-indanedione. The relationship between the wave numbers of the symmetric and asymmetric C=O stretching vibrations indicates that the effect of structure upon both vibrations is symmetric. The vibrational coupling in 1,3-cycloheptanediones and the application of Seth-Paul-Van-Duyse equation is discussed in relation to analogous results obtained for other cyclic 1,3-dicarbonyl compounds.


1991 ◽  
Vol 56 (10) ◽  
pp. 2160-2168 ◽  
Author(s):  
Josef Jirman

The 1H and 13C NMR spectra have been measured of six trans-azobenzenes substituted at 2 and 2’ positions with substituents favourable for complex formation with a metal (OH, NH2, NHCOCH3, COOH). From the standpoint of NMR such substituted trans-azobenzenes are present in solution in a rapid equilibrium following from rotation around the bond between C-1 of phenyl group and N atom of azo linkage. The predominant form has the substituent in the syn-position with respect to the free electron pair of the nearer azo nitrogen atom. The equilibrium is affected by dipolar aprotic solvents (such as hexadeuteriodimethyl sulfoxide) by decreasing the presence of the predominant form by 1 to 11%.


1991 ◽  
Vol 403 (1-2) ◽  
pp. 269-277 ◽  
Author(s):  
Vincenzo De Felice ◽  
Vincenzo G. Albano ◽  
Carlo Castellari ◽  
Maria E. Cucciolito ◽  
Augusto De Renzi

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