Synthesis,Properties, and Structures of Chromium(VI) and Chromium(V) Complexes with Heterocyclic Nitrogen Ligands

The reaction of CrO₂Cl₂ with 2, 2′‐bipyridyl or 1, 10‐phenanthroline (diimine) in CCl₄ or anhydrous CH₃CO₂H solution, produces orange‐brown diamagnetic [CrO₂Cl₂(diimine)]. The X‐ray structure of [CrO₂Cl₂(2, 2′‐bipy)] shows a six‐coordinate central chromium(VI) atom with cis‐dioxo groups trans to the diimine. In contrast, the diimines react with CrO₃ in CH₃CO₂H / conc. aqueous HCl to form bright red paramagnetic Cr^V complexes, [CrOCl₃(diimine)]. The X‐ray structure of [CrOCl₃(2, 2′‐bipy)] shows a six‐coordinate central chromium atom with mer‐chlorines and the diimine trans to O/Cl. The addition of [2, 2‐bipyH₂]Cl₂ to a solution of CrO₃ in CH₃CO₂H saturated with HCl gas, produces the Cr^V anion [2, 2′‐bipyH₂][CrOCl₄]Cl, which loses HCl on heating in vacuo to form [CrOCl₃(2, 2′‐bipy)]. IR, UV/Vis, and ¹H NMR spectra (Cr^VI only) are reported for the new complexes. Attempts to extend these routes to oxygen donor ligands, including ethers and phosphine oxides, were unsuccessful. The diimine complexes are the first structurally autheticated adducts of chromium(VI) and (V) oxide‐chlorides with neutral ligands.     

Organochromium(II) and Organonitridochromium(V) N‐Heterocyclic Carbene Complexes: Synthesis and Structural Characterization

The N‐heterocyclic carbene‐stabilized chromium(II) alkyl, aryl, and alkynyl complexes (IPM)₂CrR₂ [R = Me ( 2 ), Ph ( 3 ), C≡CPh ( 3 ); IPM = 1,3‐diisopropyl‐4,5‐dimethylimidazole‐2‐ylidene] were prepared by metathesis reactions of (IPM)₂CrCl₂ ( 1 ) with the corresponding organolithium reagents. Further reaction of 3 with an organic azide, 1‐azidoadamantane, yielded an organonitridochromium(V) compound (IPM)₂Ph₂Cr≡N ( 5 ). Compounds 2 – 5 are fully characterized by ¹H NMR and IR spectroscopy, X‐ray crystallography as well as by elemental analysis. The structural analysis shows that the metal atom adopts a nearly square‐planar arrangement in the respective 2 , 3 , and 4 and a square‐pyramidal one in 5 . The reaction of 3 with the organic azide to 5 appears a novel way to the organonitridochromium compound.     

Synthesis,Characterization, and Crystal Structure of a Chromium(III)‐Complex Containing 2,6‐Pyridinedicarboxylic Acid and 1,10‐Phenanthroline

The reaction of solution 2,6‐pyridinedicarboxylic acid and 1,10‐phenanthroline ( 1 ) with CrCl₃·6H₂O led to the complex [Cr(phen)(pydc)(H₂O)][Cr(pydc)₂]·4H₂O ( 2 ) (phen is 1,10‐phenanthroline and pydcH₂ is 2,6‐pyridinedicarboxylic acid). 2 was characterized by elemental analysis, IR spectroscopy and single‐crystal structure determination. Crystal data for 2 at ?80 °C: triclinic, space group , a = 818.5(1), b = 1492.2(1), c = 1533.6(2) pm, α = 76.45(1)°, β = 84.22(1)°, γ = 77.99(1)°, Z = 2, R₁ = 0.0416.     

Hexakis(2,4,6‐triisopropylphenyl)cyclotristannoxane – a Molecular Diorganotin Oxide with Kinetically Inert Sn–O Bonds

The single‐crystal X‐ray structure analysis of hexakis(2,4,6‐triisopropylphenyl)cyclotristannoxane, cyclo‐[(2,4,6‐i‐Pr₃‐C₆H₂)₂SnO]₃ ( 1 ), is reported and reveals this compound to contain an almost planar six‐membered ring. Redistribution reactions of 1 with cyclo‐(t‐Bu₂SnO)₃ and t‐Bu₂SiCl₂, respectively, failed and indicate an unusual kinetic inertness of the Sn–O bonds in 1 as compared to related molecular diorganotin oxides containing less bulkier substituents. The redistribution reaction of cyclo‐(t‐Bu₂SnO)₃ with cyclo‐(t‐Bu₂SnS)₂ leads to an equilibrium involving the trimeric diorganotin oxysulphides cyclo‐t‐Bu₂Sn(OSnt‐Bu₂)₂S ( 2 a ) and cyclo‐t‐Bu₂Sn(SSnt‐Bu₂)₂O ( 2 b ).     

Triphenylantimony(V) o‐amidophenolates with unsymmetrical N‐aryl group for a reversible dioxygen binding

New triphenylantimony(V) o‐amidophenolates (AP‐Me,Et)SbPh₃ (1) and (AP‐Me,iPr)SbPh₃ (2) with unsymmetrically substituted N‐aryl groups and (AP‐Et,Et)SbPh₃ (3) with symmetrical N‐aryl group {AP‐R¹,R² is 4,6‐di‐tert‐butyl‐N‐[2‐alkyl(R¹),6‐alkyl(R²)‐phenyl]‐o‐amidophenolate dianion} were synthesized and characterized in detail. Complexes were examined for dioxygen activity. The unsymmetrical complexes 1 and 2 were found to form different geometrical isomers (A and B) of spiroendoperoxides [L‐R¹,R²(O₂)]SbPh₃ (4 and 5, respectively) with different dispositions of peroxide group and N‐aryl fragment (methyl and peroxide group are on the same side of the molecule in the less shielded isomer A, and on different sides in the more hindered isomer B). The isomer A prevails over isomer B, reflecting the possibility of steric control on the dioxygen‐binding reaction. Complex 3, where R¹ = R² = Et, formed the isomers 6A and 6B as 50:50. The ratio 4A:4B was 60:40 (for methyl‐ethyl containing complex 4) and it increased up to 80:20 for methyl‐isopropyl‐containing 5. The molecular structure of isomers 4A and 4B was confirmed by X‐ray analysis. Copyright © 2010 John Wiley & Sons, Ltd.     

Coordination Frameworks based on 3,5‐Bis(imidazole‐1‐yl)­pyridine and Aromatic Dicarboxylate Ligands: Synthesis,Crystal Structures,and Photoluminescent Properties

Three metal coordination polymers [Zn(bdc)(L)(H₂O)]_n ( 1 ), [Co(pta)(L)(H₂O)₂]_n ( 2 ), and [Cd(tda)(L)(H₂O)]_n ( 3 ) [H₂bdc = 1,2‐benzene dicarboxylate acid, H₂pta = terephthalic acid, H₂tda = 2,5‐thiophenedicarboxylic acid, L = 3,5‐bis(imidazole‐1‐yl)pyridine] were synthesized and structurally characterized by IR spectroscopy, elemental analysis, X‐ray powder diffraction, and X‐ray single crystal diffraction. Complex 1 shows a three‐dimensional (3D) structure with cco topology with the symbol 6⁵ · 8, whereas complex 2 features a 3D structure with cds topology with the symbol 6⁵ · 8. Complex 3 has a 2D network constructed by the cadmium atoms bridged through the ligands tda and L. Their X‐ray powder diffraction patterns were compared with the simulated ones. Moreover, their luminescent properties were investigated in the solid state at room temperature, and the thermogravimetric analyses were carried out to study the thermal stability of the 3D networks.     

The synthesis,characterization, and crystal structures of poly(2,6‐naphthalenebenzobisoxazole) and poly(1,5‐naphthalenebenzobisoxazole)

The rigid‐rod polymers, poly(2,6‐naphthalenebenzobisoxazole) (Naph‐2,6‐PBO) and poly(1,5‐naphthalenebenzobisoxazole) (Naph‐1,5‐PBO) were synthesized by high temperature polycondensation of isomeric naphthalene dicarboxylic acids with 4,6‐diaminoresorcinol dihydrochloride in polyphosphoric acid. Expectedly, these polymers were found to have high thermal as well as thermooxidative stabilities, similar to what has been reported for other polymers of this class. The chain conformations of Naph‐2,6‐PBO and Naph‐1,5‐PBO were trans and the crystal structures of Naph‐2,6‐PBO and Naph‐1,5‐PBO had the three‐dimensional order, although the axial disorder existed for both Naph‐2,6‐PBO and Naph‐1,5‐PBO. Naph‐2,6‐PBO exhibited a more pronounced axial disorder than Naph‐1,5‐PBO because of its more linear shape. The repeat unit distance for Naph‐2,6‐PBO (14.15 Å) was found to be larger compared with that of Naph‐1,5‐PBO (12.45 Å) because of the more kinked structure of the latter. The extents of staggering between the adjacent chains in the ac projection of the crystal structure were 0.25c and 0.23c for Naph‐2,6‐PBO and Naph‐1,5‐PBO, respectively. Naph‐1,5‐PBO has a more kinked and twisted chain structure relative to Naph‐2,6‐PBO. The kinked and twisted chain structure of Naph‐1,5‐PBO in the crystal seems to prevent slippage between adjacent chains in the crystal structure. The more perfect crystal structure of Naph‐1,5‐PBO may be due to this difficulty in the occurrence of the slippage. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1948–1957, 2006     

Syntheses,Structures, and Catalytic Activities of Copper(I) Complexes with the Ligand 2(4,5‐Diphenyl‐1H‐imidazol‐2‐yl)­pyridine

Two copper(I) complexes of compositions [Cu(HL)I]₂ · EtOH ( 1 ) and [Cu(HL)₃]I · MeOH ( 2 ) were synthesized via the reactions of HL [HL = 2(4,5‐diphenyl‐1H‐imidazol‐2‐yl)pyridine] and CuI in EtOH and MeOH, respectively, under solvothermal conditions. The complexes were characterized by X‐ray single crystal diffraction, IR spectroscopy, and elemental analysis. Compounds 1 and 2 are catalytically active towards ketalization reaction, giving various ketals under mild conditions.     

Crystal Structure and Spectroscopic Properties of Bis[trans‐dichlorobis(2,2‐dimethylpropane‐1,3‐diamine)chromium(III)] Tetrachlorozincate

The structure of trans‐[Cr(Me₂tn)₂Cl₂]₂ZnCl₄ (Me₂tn = 2,2‐dimethylpropane‐1,3‐diamine) was determined by a single‐crystal X‐ray diffraction study at 173 K. The analysis reveals that there are three crystallographically independent chromium(III) complex cations in the title compound. The chromium(III) atoms are coordinated by four nitrogen atoms of Me₂tn and two chlorine atoms in a trans arrangement, displaying a distorted octahedral geometry. The two six‐membered chelate rings in three complex cations are oriented in an anti chair–chair conformation with respect to each other. The Cr–N and Cr–Cl bond lengths average 2.0862(2) and 2.3112(6) Å, respectively. The ZnCl₄^2– have slightly distorted tetrahedral arrangement with Zn–Cl lengths and the Cl–Zn–Cl angles are influenced by hydrogen bonding. The resolved absorption maxima in the electronic d–d spectrum were fitted with a secular determinant for a quartet energy state of the d³ configuration in a tetragonal field. It is confirmed that the nitrogen atoms of the Me₂tn ligand are strong σ donors, but the chloro ligands have weak σ‐ and π donor properties toward the chromium(III) ion.     

Festkörper‐NMR‐Untersuchungen an Natriumoxothiophosphaten(V)

Solid State NMR Investigations on Sodium Oxothiophosphates(V) Sodium monothiophosphate(V) Na₃PO₃S is dimorphic. The metastable high temperature modification β‐Na₃PO₃S crystallizes hexagonal with a = 8.996(4) and c = 5.216(2)Å. According to ³¹P solid state NMR experiments, α‐Na₃PO₃S exhibits at 20 °C a non‐axial‐symmetric environment for the phosphorus nuclei in contrast to the results of the refined crystal structure. This discrepancy is discussed assuming ordered and disordered structural models. However, at 490 °C the chemical shift tensor of the phosphorus nuclei in α‐Na₃PO₃S is axial‐symmetric. So, the distortion of the phosphorus environment is abolished by the thermal motion of the atoms. The number of crystallographically distinguishable positions for phosphorus and for sodium in Na₃PO₂S₂ and Na₃POS₃ can be confirmed in good agreement with their crystal structures using solid state NMR spectroscopy.     

Nitrogen‐Rich Alkali Metal Salts (Na and K) of [Bis(N,N‐bis(1H‐tetrazol‐5‐yl)amine)‐zinc(II)] Anion: Syntheses,Crystal Structures,and Energetic Properties

Two nitrogen‐rich alkali metal salts based on nitrogen‐rich anion [Zn(bta)₂]^2–: {[Na₂Zn(bta)₂(H₂O)₈] · H₂O}_n ( 1 ) and {[K₂Zn(bta)₂(H₂O)₄]}_n ( 2 ) were synthesized by reactions of alkali hydroxide, N,N‐bis(1H‐tetrazol‐5‐yl)amine (H₂bta), and zinc chloride in aqueous solutions. The crystal structures of 1 and 2 were determined by low temperature single‐crystal X‐ray diffraction and fully characterized by elemental analysis and FT‐IR spectroscopy. The structures demonstrate that an infinite 1‐dimensional (1D) chain structure is constructed by Na⁺ ions and bridging water molecules in compound 1 , which is connected by extensive hydrogen bonds forming a complex 3D network, whereas compound 2 features a more complicated 3D metal‐organic framework (MOF). The thermal behaviors of 1 and 2 were investigated by differential scanning calorimetry (DSC) measurements. The DSC results illustrate that both compounds exhibit high thermal stabilities (decomposition temperature > 345 °C). In addition, the heats of formation were calculated on the basis of the experimental constant‐volume energies of combustion measured by using bomb calorimetry. Lastly, the sensitivities towards impact and friction were assessed according to Bundesamt für Materialforschung (BAM) standard methods.     

4‐Nitro‐3‐(5‐tetrazole)furoxan and Its Salts: Synthesis,Characterization, and Energetic Properties

A series of new energetic salts based on 4‐nitro‐3‐(5‐tetrazole)furoxan (HTNF) has been synthesized. All of the salts have been fully characterized by nuclear magnetic resonance (¹H and ¹³C), infrared (IR) spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). The crystal structures of neutral HTNF ( 3 ) and its ammonium ( 4 ) and N‐carbamoylguanidinium salts ( 9 ) have been determined by single‐crystal X‐ray diffraction analysis. The densities of 3 and its nine salts were found to range from 1.63 to 1.84 g cm^?3. Impact sensitivities have been determined by hammer tests, and the results ranged from 2 J (very sensitive) to >40 J (insensitive). Theoretical performance calculations (Gaussian 03 and EXPLO 5.05) provided detonation pressures and velocities for the ionic compounds 4 – 12 in the ranges 25.5–36.2 GPa and 7934–8919 m s^?1, respectively, which make them competitive energetic materials.     

Structures of X 34‐nylons in chain‐folded lamellae and gel‐spun fibers

Structural studies and morphological features of a new family of linear, aliphatic even–even, X 34‐nylons, with X = 2, 4, 6, 8, 10, and 12, are investigated with X‐ray diffraction and electron microscopy. Solution‐grown crystals were obtained by isothermal crystallization from N,N‐dimethylformamide solutions. The thickness of lamellar‐like crystals was orders of magnitude less than the chain lengths of the polymer samples used, implying that the chains fold to form chain‐folded lamellae. The results bear a close resemblance, with the noticeable exception of 2 34‐nylon, to those reported for nylon 6 6 and other even–even nylon chain‐folded lamellar crystals. The basic structure of the straight‐stem lamellar core is similar to that of the classic nylon 6 6 triclinic α structure, and the chains tilt ≈42° relative to the lamellar normal. In the case of 2 34‐nylon, the structure resembles the 2 Y nylon series, and the chain tilt angle reduces to 36.6°. These combined results suggest that, even with a relatively low frequency of amide units along the backbone of these molecules, hydrogen bonding is still the dominant element in controlling the behavior, structure, and properties of these polymers. In addition, gels were prepared in concentrated sulfuric acid, and gel‐spun fibers were studied using X‐ray diffraction. The data are interpreted in terms of a modified nylon triclinic α structure that bears a resemblance to the structure of even–even nylons at elevated temperatures. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2685–2692, 2002     

Complex Salts of Lanthanide(III) Nitrates from Di­pyridylamine: Preparation,Structural, and Thermoanalytical ­Investigation

The reaction of a lanthanide(III) nitrate (Ln = Pr, Nd) with the base 2, 2′‐dipyridylamine (dpamH) afforded two very stable microcrystalline compounds. These compounds were characterized as complex salts with the general formula [Ln(NO₃)₆] · 3[dpamH‐H⁺] · H₂O, where the dpamH ligand is not coordinated, but exists in its protonated form serving as counterion (dipyridylammonium cation), as it was revealed by single‐crystal X‐ray diffraction studies. Each one of the nitrate ions is coordinated, however, in a bidentate manner with the lanthanide(III) ion, which obtains coordination number twelve. All organic dpamH‐H⁺ cations are arranged in two columns parallel to the a axis of the cell forming pairs of almost parallel cationic molecules at a distance of about 3.5 Å. Inside each pair the molecules interact by strong π–π interactions. The water molecules, arranged between the inorganic anions [Ln(NO₃)₆]^3–, bridge them by strong hydrogen bonds, involving the water proton and one nitrate oxygen. The lattice can be described as made from successive organic and inorganic alternating parallel columns interacting between them with strong hydrogen bonds. The thermal stability and decomposition mode of the two lanthanide compounds were studied by the simultaneous TG/DTG‐DTA technique and compared with the starting hexahydrate lanthanide(III) salts and the dipyridylamine.     

Synthesis,spectroscopic and X‐ray single‐crystal structure study of bis(2‐methoxy‐ethanolato)‐bis(8‐quinolinato)titanium(IV)

Reaction of Ti(OCH₂CH₂OR)₄ (R?CH₃ and C₂H₅) with 8‐hydroxyquinoline in benzene at room temperature resulted in the formation of Ti(C₉H₆NO)₂(OCH₂CH₂OR)₂, characterized by IR, ¹H‐NMR, UV and mass spectroscopies. The molecular structure of Ti(C₉H₆NO)₂(OCH₂CH₂OCH₃)₂ has been determined by single‐crystal X‐ray structure analysis. The geometry at titanium is a distorted octahedron, with the nitrogen atoms of quinolinate occupying the trans position with respect to oxygens of the 2‐methoxyethoxy groups. The prepared quinolinate derivatives of titanium alkoxides are very stable towards hydrolysis and harsh conditions are required for hydrolytic cleavage. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis,Characterization, and X‐ray Crystal Structures of (Diphosphine)Ni(dmit) and (Diphosphine)Ni(dmio) (Diphosphine = dppv,dppb) Complexes

Four complexes with the ligands dmit and dmio were synthesized. Reaction of (PhCO)₂(dmit) and (PhCO)₂(dmio) with MeONa afforded the intermediates 2‐thioxo‐1,3‐dithiole‐4,5‐dithiolate dianion and 2‐oxo‐1,3‐dithiole‐4,5‐dithiolate dianion, respectively. Reaction of the two dianions with (diphosphine)NiCl₂ [diphosphine = (Z)‐1, 2‐bis(diphenylphosphanyl)ethane (dppv), 1,2‐bis(diphenylphosphanyl)benzene (dppb)] gave (dppv)Ni(dmit) ( 1 ), (dppb)Ni(dmit) ( 2 ), (dppv)Ni(dmio) ( 3 ), and (dppb)Ni(dmio) ( 4 ). This synthesis route was found to be an efficient pathway to prepare dmit and dmio ligand complexes. Complexes, 1 – 4 were fully characterized by elemental analysis and IR, ¹H NMR, ¹³C NMR, and ³¹P NMR spectroscopy. In addition, the molecular structures of 1 , 3 and 4 were established by X‐ray diffraction.     

Synthesis,Structures, and Properties of Two Novel Coordination Polymers with a V‐shaped Diphosphonate Ligand

Two novel coordination polymers, [Cu(H₂L)(bipy)(H₂O)₂] · H₂O ( 1 ) and [Ni₂(H₂L)(bipy)_2.5(H₂O)₆] · (H₂L) · 7H₂O ( 2 ) with the V‐shaped diphosphonate ligand (2,4,6‐trimethyl‐1,3‐phenylene)bis(methylene)diphosphonic acid (H₄L) were synthesized via hydrothermal reactions in the presence of auxiliary ligand 4,4′‐bipyridine. Their structures were determined by single‐crystal X‐ray diffraction and further characterized by elemental analysis, infrared spectroscopy (IR), and thermogravimetric analysis (TGA). Compound 1 crystallizes in the Pnma space group and compound 2 crystallizes in the P2₁2₁2 space group. They display square‐grid layer and bilayer two‐dimensional network, respectively.     

Solid Solution Formation between Vanadium(V) and ­Tungs­ten(V) Oxide Phosphate

The solid solutions (V_1–xW_x)OPO₄ with β‐VOPO₄ structure type (0.0 ≤ x ≤ 0.01) and α_II‐VOPO₄ structure type (0.04 ≤ x ≤ 0.26) were obtained from mixtures of V^VOPO₄ and W^VOPO₄ by conventional solid state reactions and by solution combustion synthesis. Single crystals of up to 3 mm edge length were obtained by chemical vapor transport (CVT) (800 → 700 °C, Cl₂ as a transporting agent). Single crystal structure refinements of crystals at x = 0.10 [a = 6.0503(2) Å, c = 4.3618(4) Å, R₁ = 0.021, wR₂ = 0.058, 21 parameters, 344 independent reflections] and x = 0.26 [a = 6.0979(2) Å, c = 4.2995(1) Å, R₁ = 0.030, wR₂ = 0.081, 21 parameters, 346 independent reflections] confirm the α_II‐VOPO₄ structure type (P4/n, Z = 2) with mixed occupancy V/W for the metal site. Due to the specific redox behavior of W⁵⁺ and V⁵⁺, solid solutions (V_1–xW_x)OPO₄ should be formulated as (V^IV_xV^V_1–2xW^VI_x)OPO₄. The valence states of vanadium and tungsten are confirmed by XPS measurements. V⁴⁺ with d¹ configuration was identified by EPR spectroscopy and magnetic measurements. Electronic spectra of the solid solutions show the IVCT(V⁴⁺ → V⁵⁺) and the LMCT(O^2– → V⁵⁺). (V_0.74W_0.26)OPO₄ powders exhibit semi‐conducting behavior (E_g = 0.7 eV).     

Syntheses,Structures, and Magnetism of Trinuclear Zn2Ln Complexes with 2,6‐Dipicolinoylbis(N,N‐diethylthiourea)

The bifunctional ligand 2,6‐dipicolinoylbis(N,N‐diethylthiourea) (H₂L) readily reacts with mixtures of Zn(CH₃COO)₂ and LnCl₃ in MeOH at ambient temperature with formation of trinuclear heterobimetallic complexes [Zn₂Ln(L)₂(OAc)₃] ( 1a – 1f ) (Ln = Ce, Nd, Sm, Gd, Dy, Er). The X‐ray single‐crystal diffraction and structural studies of the complexes revealed their isostructural nature, in which two doubly‐charged ligands {L^2–} bind two Zn²⁺ ions with the terminal acylthiourea sites and one Ln³⁺ ion with the central 2,6‐pyridinedicarboxamide site. In the complexes, the coordination numbers of Ln^III and Zn^II ions are 9 and 5, respectively. Magnetic properties of the complexes were studied by temperature‐dependent dc magnetic measurements. The observed μ_eff values at room temperature are all closed to the calculated values. Fitting χ_M and M data of [Zn₂Gd(L)₂(OAc)₃] ( 1d ) shows a g_iso value of 1.94.     

Cold‐drawn induced microstructure in PVC‐bentonite nanocomposites

The mechanical properties and cold drawn‐induced micro and nanostructure of polyvinyl chloride (PVC)‐bentonite nanocomposites have been investigated. Molded sheets with 5 wt% concentration of bentonite and two processing additives were melt extruded and two‐roll‐milled processed. The flame retardant additive promoted polymer intercalation whereas a pigment dispersant promoted clay exfoliation, the polymer matrix showed isotropic orientation. The intercalated nanocomposite exhibited nanoplates oriented with their planes parallel to the molded sheet surface and the Young's modulus and yield stress were significantly enhanced relative to neat PVC. The strain at fracture (～144%) was slightly reduced relative to the matrix (～167%). Cold drawing induced molecular chain orientation along the tensile axis and preserved the orientation of the intercalated nanoclays. The fracture mechanism, as investigated via scanning electron microscopy (SEM) revealed plastic fracture mechanism (similar to neat PVC). On the other hand, the exfoliated nanocomposite did not show any improvement in mechanical properties but rather a significant decay of strain at fracture (～44%). The fractured region, as examined by SEM, exhibited microvoid morphology. Analysis of the fractured region showed PVC macromolecules oriented along the tensile axis but no preferred orientation of the nanoclays. The limited strain at fracture found for this material appears to be associated with the initially randomly oriented nanoclays being unable to orient under the tensile deformation. The nanoclays would act as stress concentrators leading to rapid material's failure due to loss of adhesion with the polymer matrix. The results suggest that exfoliated nanoclays could play a detrimental role when the nanocomposite is subjected to large deformations at temperatures well within the glassy regime. Copyright © 2009 John Wiley & Sons, Ltd.