Linear I3 Research Articles

(C3H7NH3)4Bi1-xSbxI9: 0D hybrid halide perovskite-like compounds with isolated triiodide units.

Antimony/bismuth-based organic-inorganic hybrid halide perovskite-like compounds have generated enormous research interest due to their excellent optical properties. Exploration of new compounds and understanding of their structural stability and optoelectronic properties is of utmost importance for practical applications of these materials. We report two new 0D perovskite-like compounds and their solid solution, (C3H7NH3)4Bi1-xSbxI9, having propyl amine as the spacer cation and iodine as the halide ion. All compounds crystallized in the space group C2/m at room temperature and undergo a phase transition from C2/m to P21/c at low temperature (90 K) as observed from the single-crystal study. A low-temperature (250 K, 180 K, 150 K and 90 K) single-crystal study shows that the (PA)4BiI9 compound retains the monoclinic space group C2/m until 150 K and undergoes a phase transition to the P21/c space group at 90 K. Further, it is observed that ordering, rearrangement and relaxation of the long-chain propyl amine group are primarily responsible for the structural transition. The structure contains [(Bi/Sb)I6]3- polyhedra along with linear I3- units, giving rise to the formula of (PA)3(Bi/Sb)I6·(PA)I3. The I3- units interact poorly while the [MI6]3- (M = Bi, Sb) octahedral units interact significantly with spacer cations via the H-bond, resulting in more distortion in these octahedral units. Theoretical calculations revealed that iodide ions have dual roles and contribute largely to both the valence band maxima and conduction band minima in these compounds. From both experimental and theoretical calculations, it is observed that the pristine compounds are of the indirect band gap-type and Sb substitution in (PA)4Bi1-xSbxI9 led to a gradual decrease in the band gap.

Solvent Effects on the Spin Crossover Properties of Manganese (III) (sal‐N‐1,5,8,12) Complexes

AbstractThe interplay of host‐guest interactions and controlled modulation of spin‐crossover (SCO) behavior is one of the most exploited topics regarding data storage, molecular sensing, and optical technologies. This study examines the effect of solvents on the spin‐crossover (SCO) behavior of manganese(III) complexes [Mn(sal‐N‐1,5,8,12)]I•S (S=CH3OH, C2H5OH, CH3CN) (1) and [Mn(sal‐N‐1,5,8,12)]I3 (2), where (sal‐N‐1,5,8,12)2− is 2,2′‐((1E,13E)‐2,6,9,13‐tetraazatetradeca‐1,13‐diene‐1,14‐diyl)diphenol synthesized by salicylaldehyde and 1,2‐bis(3‐aminopropylamino)ethane. The complexes, crystallizing in orthorhombic or monoclinic systems, exhibit similar supramolecular arrangements with one‐dimensional cationic chains at low temperatures. Magnetic studies reveal that solvent inclusion sharpens the SCO transition and lowers the transition temperature. Specifically, 1⋅CH3OH shows a 13 K thermal hysteresis due to methanol‘s mobility through the channels in the cationic framework. Although the solvent‐free compound was not obtained, compound 2 with a linear I3− anion was synthesized, displaying extensive cation‐anion contacts and a distinct 13 K thermal hysteresis upon heating due to altered intermolecular cooperativity. This emphasizes the significant role of solvent introduction and variation in crystal packing and their impact on the SCO properties.

Effect of OH Segmental Length on the Iodine Complex Formation of Ethylene–Vinyl Alcohol Random Copolymers

Poly(vinyl alcohol) (PVA) is known to form the crystalline complexes with iodine ions, in which the linear I3– ions form the columnar arrays and are connected to the neighboring PVA chains of planar-zigzag conformation through the charge transfer between OH groups and I3– ions. In order to clarify the effective OH segmental length necessary for the formation of such an iodine complex along the chain axis, the complex formation behavior has been investigated systematically for a series of ethylene–vinyl alcohol (EVOH) random copolymers on the basis of the experimental data of 2D X-ray diffraction, visible-ultraviolet (UV–Vis) absorption spectra, Raman spectra, and infrared spectra. By comparing the observed X-ray diffraction patterns, the EVOH copolymers with VOH content near 100 mol % were found to take the relatively regular complex II structure, while the EVOH copolymers of 70–50 VOH mol % were found to take the structure of complex I, in which the PVA zigzag chains are packed together randomly with and...

Molecular properties of the PCO radical: heat of formation and the isomerization pathways

The potential energy surface of [P,C,O] system in the ground state was investigated by quantum chemical methods. Four different isomers were characterized at the B3LYP/aug-cc-pVTZ: COP (i1), cPCO (i2), PCO (i3), and CPO (i4). The linear species i3 is the global minimum in the ground state surface, while i4 is a bent structure, and i2 is a cyclic isomer. In view to evaluate the bond nature of each isomer, a QTAIM and a NBO analyses were applied. The triangular species presents a ring critical point which confirms its cyclic structure instead of a T-shape one. The stability increases in the following order: i3 > i2 > i1 > i4. The energy gap between i3 and i2 ranges from 49.20 to 51.15kcalmol(-1). The reaction barrier energies that converge into the direction of i3 showed values around 10kcal mol(-1), while the reverse barriers are considerably large (62.85kcalmol(-1)). The i3 heat of formation at 298K ranges from 11.83 to 19.41kcalmol(-1).

Extensive theoretical investigation: influence of the electrostatic environment on the I3 −···I3 − anion–anion interaction

A theoretical study of the triiodide ion and I3−···I3− interactions in the dimer was performed using various levels of theory and basis sets. Optimisations in the gas phase and in an implicit polarisable continuum solvent model with a variety of solvents showed that there is a significant dependence of the I3−···I3− interaction energy on the dielectric constant. We found that the MP2/cc-pVTZ-pp level of theory came closest to reproducing the I3− bondlength and the I3−···I3− intermolecular distance averages obtained from the Cambridge Structural Database (CSD). In addition, MP2/cc-pVTZ-pp results also compare well with the I3−···I3− interaction energy calculated at the CCSD/aug-cc-pVTZ-pp//MP2/cc-pVTZ-pp level of theory. When considering the I–I bondlength (2.92 A) in the linear I3− ion and I3−···I3− intermolecular distance (3.80 A), M06-2X performs best for the former and BP86 for the latter. We found that in general, the 21 density functionals tested (4 GGAs, 11 Hybrid GGAs, 1 meta-GGA and 5 containing DFT-D2 corrections) underestimate the interaction energy, including those with dispersion corrections. However, PBE-D2 gave an interaction energy which is less than 2 % from the CCSD/aug-cc-pVTZ-pp//MP2/cc-pVTZ-pp result.

Factors Controlling Asymmetrization of the Simplest Linear I3–and I42–Polyiodides with Implications for the Nature of Halogen Bonding

This paper investigates geometric and electronic features of linear I3– and I42– anions, as building blocks of larger polyiodides. Most experimental structures are quasi D∞h, although one lateral linkage is occasionally elongated with I···I separations approaching those of I···I–R– species, typical of halogen bonding (HalB). Hirshfeld surfaces from crystal data highlight solid state effects depending on the distribution of the counterions around I3– or I42– units. Corresponding experimental asymmetries have been mimicked with density functional theory calculations through different surroundings of positive point charges. The consequent deformations are interpreted in terms of the s/p rehybridizations occurring at the central I atom(s) of the populated frontier σ* wave functions. The origin is a charge-induced variation of the orbital energies at lateral iodides (electronegativity), hence by their the donor power in a nucleophilic attack. The calculations also provide energy information on I2 + I– or I2 + 2I– additions, and, in solvent, the intrinsic energy stability of I42– is for the first time validated. In the absence of positive charge perturbations, the 1– charge of a remote iodide polarizes I3– and promotes incipient electrostatic attraction, which is quickly accompanied by electron transfer with a generalized σ delocalization throughout I42–. Implicit orbital overlap supports a covalent picture, or better to say hypervalency, given the electron richness of the central atoms. Molecular electrostatic potential (MEP) surfaces are expected to show σ holes in support of the purely electrostatic HalB model, typically proposed for I···I–R– systems. However, the computed surfaces show little evidence of σ holes in the equilibrium adducts I3–, I42– and I···I–R– suggesting that HalB cannot be purely electrostatic.

Crystal and molecular structure of diphenyliodonium triiodide

A new salt diphenyliodonium triiodide (C12H10I4) was obtained. The [C12H10I+][I3−] compound was isolated as red brown crystals and studied by single-crystal X-ray diffraction. The structure of diphenyliodonium triiodide consists of separate, virtually linear I3− anions and C12H10I+ cations. Strong intermolecular anion-anion (I3−…I3−) and anion-cation (I3−…I+) interactions in the crystal structure leads to a change in the symmetry of triiodide ions. The complex formation in the system organic cation iodide-elementary iodine was studied by spectrophotometry. The complex composition was found (1: 1), and the stability constant of the complex in chloroform was determined (loggB = 3.91).

Isolated Triiodide and Pentaiodide Anions in the Crystal Structure of [Rb(Dibenzopyridino‐18‐Crown‐6)2]2(I3)(I5)

AbstractRed shiny crystals of [Rb(dibenzopyridino‐18‐crown‐6)2]2(I3)(I5) were obtained from a dichloromethane/ethanol solution of RbI, I2 and dibenzopyridino‐18‐crown‐6. Triclinic, $\rm P{\bar 1}$, a = 1494.3(1), b = 1534.1(1), c = 2412.9(2) pm, α = 76.95(1), β = 83.58(1), γ = 68.67(1)°, V = 5016.7(7) 106·pm3, Z = 2. The crystal structure consists of [Rb(dbp18c6)2]+ cations leaving suitable three‐dimensional channels for the linear I3− and V‐shaped I5− anions which are isolated from each other.

Stability and molecular and crystal structure of 9-amino-10-methylacridinium triiodide

Mixing of equimolar amounts of 9-amino-10-methylacridinium iodide and elemental iodine yields 9-amino-10-methylacridinium triiodide. The complexation in the organic cation iodide-elemental iodine system has been studied by spectrophotometry. The composition and the stability constant of the complex formed in a chloroform solution have been determined. The compound [C14H13N2]+[I3]− has been isolated as dark red plate crystals and studied by X-ray diffraction. The structure is formed by linear I3− anions and 9-amino-10-methylacridinium cations assembled through π-π stacking. The cations in the stacks are shifted by approximately one ring with respect to one another. The triiodide ion is linear, the average I-I bond length (2.915 A) is close to the standard value. The stacking reflects the specific nature of the organic cation, while the presence of the I3− counterion results in extension of the system of hydrogen bonds.

Komplexe einwertiger Dibenzo‐18‐Krone‐6‐Kationen mit Triiodid als Anionen

AbstractComplexes of Monovalent Dibenzo‐18‐crown‐6 Cations with Triiodide as AnionsThe new polyiodides [NH4(db18c6)]2(I3)2 (1), [NH4(db18c6)](db18c6)I3 (2), [Na1/2(db18c6)H2O]2I3 (3), [Rb(db18c6)]I3 (4), [Rb(db18c6)]2(I3)2 (5), [Cs(db18c6)]I3 (6), and [Cs2(db18c6)3][Cs(db18c6)3/2](I3)3 (7) were obtained from reactions of dibenzo‐18‐crown‐6 (db18c6) and iodine with NH4I, NaI, RbI, and CsI. Their crystal structures were determined by single‐crystal X‐ray diffraction. (1) M = NH4, (5) M = Rb: monoclinic, P21/n, a = 1409,67(8), b = 2211,63(14), c = 1627,16(10) pm, β = 101,030(5)°, Z = 4 (crystal data for M = NH4); (2): monoclinic, Pn, a = 1345,26(14), b = 773,82(4), c = 2095,10(20) pm, β = 94,439(8)°, Z = 2; (3): orthorhombic, Pnaa, a = 931,59(13), b = 2213,3(5), c = 2223,9(4) pm, Z = 4; (4): monoclinic, P21/n, a = 999,50(6), b = 1711,33(10), c = 1517,45(9) pm, β = 99,021(5)°, Z = 4; (6): triclinic, $\rm P{\bar 1}$, a = 705,16(9), b = 1137,93(14), c = 1678,90(20) pm, α = 73,719(10), β = 79,782(10), γ = 83,669(10)°, Z = 2; (7): triclinic, $\rm P{\bar 1}$, a = 1519,25(6), b = 1702,49(7), c = 2136,41(9) pm, α = 102,641(3), β = 101,989(3), γ = 91,911(3)°, Z = 2. 1 : 1 cations centered by M, [M(db18c6)]+, are found in the structures of (1 – 6). In contrast, the triple decker cation found in (7) is less common. The crystal structures are completed by mostly asymmetrically linear I3− anions.

Bis[N,N′-bis(3,3-diphenylprop-2-enylidene)ethane-1,2-diamine-κ2N,N′]copper(I) triiodide

The title complex, [Cu(C32H28N2)2]I3, contains cations having CuI coordinated by four N atoms of two N,N′-bis­(3,3-diphenyl­prop-2-enyl­idene)ethane-1,2-diamine (Phca2en) ligands in a distorted tetra­hedral fashion and isolated linear I3− anions. The Phca2en ligand adopts a Z,Z conformation and acts as a bidentate ligand coordinating via two N atoms to the Cu atom. The Cu and central I atoms are located on twofold axes.

Status of the Terawatt Accumulator Accelerator project

The construction of the Terawatt Accumulator (TWAC) facility is nearly completed at the ITEP in Moscow. All the major milestones have been successfully passed with a beam of carbon ions, except for the final result (the high power beam accumulation), which is on the way. The beam of C4+ ions delivered by the laser ion source is accelerated up to the energy of 300 MeV/amu by two steps—in the linear injector I3 and in the booster synchrotron UK. The accelerated beam is extracted from the UK ring and transferred to the U10 accumulator ring. Non-Liouvillian stripping technique (C4+ ⇒ C6+) is applied for stacking of C6+ batches into the accumulator ring U10. First experiments with extracted beam of ions have started in 2002. Status of the TWAC components, current results of activities aiming at mastering the ion beam stacking technique, and outlook for the TWAC advance are presented.

Ba(Benzo-15-Krone-5)2](In)2: Darstellung und strukturelle Charakterisierung eines Triiodids (n = 3) und eines Heptaiodids (n = 7)

[Ba(benzo-15-crown-5)2](I3)2 and [Ba(benzo-15-crown-5)2](I7)2 can be obtained in crystalline form by reacting benzo-15-crown-5 (C14H20O5), barium iodide (BaI2), and iodine (I2) in ethan-ole /dichloromethane. The triiodide consists of a sandwich-like cation [Ba(benzo-15-crown-5)2]2+ and an isolated symmetrically linear I3- anion. The unusual I7- anion in the heptaiodide can be described as a V-shaped pentaiodide unit, which is connected with a slightly widened iodine molecule to the rare Z-form of the heptaiodide ion. In the crystal structure, secondary bonding distances lead to almost planar ten-membered iodine rings, which are connected by common edges to form staircase-like bands.

Trans-dichlorotetrakis(4-methylpyridine)silicon bis(triiodide) chloroform solvate

At 173 K, the dication of the title compound, C24H28Cl2N4Si2+·2I3−·CHCl3, is located on a crystallographic fourfold rotation axis. The chloro ligands occupy axial positions and the four 4-methyl­pyridine ligands lie in the equatorial plane. The almost linear I3− ion is located on a crystallographic mirror plane and displays two significantly different I—I bond lengths. Furthermore, chloro­form mol­ecules, which are disordered about a centre of inversion, fill the remaining gaps in the crystal structure.

The crystal packing of [M(phen)3]I7 (M = Mn, Fe)

The crystallisation, crystal structures, and crystal packing of [Mn(phen)3]I7 and [Fe(phen)3]I7 are reported. The crystal lattices are isomorphous, but there are informative small differences between the two structures. The [M(phen)3]2+ complexes occur as parallel (P4AE)∞ chains, forming two parallel fourfold aryl embraces (P4AE) with adjacent cations. The polyiodide components occur between the chains, and in the (phen)2 grooves of the complexes. The stoichiometry {I7}2- is comprised structurally of discrete I3- and half of centrosymmetric [I8]2- units. These [I8]2- units contain twofold 50:50 disorder, and are either zig-zag I82-, or I2 plus I62-. Details of the disorder are different in the two crystals, reflecting the soft I...I potentials involved. The I82- ion is normal, but the I62- species, as a centrosymmetric pair of linear I3-, appears to be unprecedented. The disordered polyiodide segments are positioned in a filled aryl box motif formed by (phen)2 grooves from complexes in adjacent (P4AE)∞ chains. These crystal structures illustrate again the pattern of complementary orthogonality of phen ligands and polyiodide segments

Vibrational Dynamics of the I3 Radical: A Semiempirical Potential Surface, and Semiclassical Calculation of the Anion Photoelectron Spectrum

The semiempirical diatomics in molecules (DIM) approach is used to model the potential surface for ground-state vibration of a linear I3 molecule. We use this system to explore semiclassical methods for treating quantal nuclear vibrations by computing the photoelectron spectrum of I3- which produces vibrationally excited I3 . We compare semiclassical results with full quantum calculations and experimental results recently reported by Neumark and co-workers. (Taylor, T. R.; Asmis, K.R.; Zanni, M. T.; Neumark, D. M. J. Chem. Phys. 1999, 110, 7607.)

Die Kristallstruktur von [Me3PN(H)PMe3]4l28, einem Polyiodid mit I3--, l82-- und I14 4--Ionen Crystal / Structure of [Me3PN(H)PMe3]4I28, a Polyiodide with I3-, I8 2- , and I 14 4- Ions

Abstract Black-red single crystals of [Me3PN(H)PMe3]4I28 have been prepared by the reaction of [Me3PNPMe3]I with iodine in dichloromethane solution in the presence of Me3SiI and traces of water. The polyiodide crystallizes triclinically in the space group P1̄ with two formula units per unit cell with the lattice dimensions a = 831.2(1), b = 1661.2(3), c = 1739.0(3) pm, α = 87.26(1)°, β = 79.48(1)°, γ = 78.17(1)°. The structure consists of [Me3PN(H)PMe3]2+ ions, linear I3- ions, z-shaped I82- ions, and zig-zag chains of I14 4- ions, the terminal iodine atoms of which form I···H-N hydrogen bridges to the cations.

129I and125Te Mössbauer studies of polyvinyl alcohol films doped with iodine

129I and125Te Mossbauer measurements have been performed on unidirectionally stretched iodine-doped polyvinyl alcohol (PVA) films which are widely used as optical polarizers. From the129I measurements iodine is observed to be in the form of linear polyiodides, I3− and I5−, lying parallel to the stretch direction of the PVA films. From the125I emission Mossbauer measurements the structural arrangement of the iodine-PVA complex is also discussed.

New cation-radical salts based on BEDT-TTF symmetric analogs with polyhalide anions

A new series of cation-radical salts based on symmetric BEDT-TTF (ET) analogs, BT, SPT, OPT, CPT, has been synthesized with linear anions I3−, IBr2−, ICl2−. Their crystal structures and conducting properties have been studied. The first cation-radical salt (BT)2Cl2H5O2 with a new complex anion (Cl2H5O2)−, which consists of 2Cl− and a hydroxonium ion H5O2+, has been obtained. The salt is an organic metal with the metal-insulator transition in the region of ≈80 K.

Raman spectroscopic investigation of N‐alkylurotropinium polyiodides

AbstractN‐Alkylurotropinium polyiodides, UrRIx, with different iodine contents and different sizes of alkyl group were investigated by Raman spectroscopy. The spectra were recorded for wavenumber shifts up to 500 cm−1. It was found that the triiodides, UrRI3, contain a symmetrical linear I3− ion. The pentaiodides, UrRI5, contain no triiodide unit; the anion structure can be described as nearly symmetrical, rectangular L‐shaped I5−. An interpretation of the Raman spectra of the heptaiodides, UrRI7, is that the anion corresponds to an I5−. I2 structure. This is the first proof of such a heptaiodide. A review of previously published data on the Raman spectra of polyiodides is also given.