Tetrachloroferrate(III) Complexes Containing Some Heteroaromatic Organic Cations: Structures and Magnetic Properties

The crystal structures of tetrachloroferrate(III) complexes having stoichiometry (BH)⁺ [FeCl₄]^? (where B = isoquinoline and 4‐aminopyridine) were determined at 100 K. While weak interactions, particularly N–H···Cl hydrogen bonds, are evident in the structures, distances between the Fe(III) centers are quite long in both cases. The structure of the compound with B = quinoline was compared with that previously established at room temperature, and showed that neither solid‐solid nor magnetic phase transitions occurred in this temperature range. Magnetic measurements on the paramagnetic powders indicate weak antiferromagnetic interactions transmitted through the crystal lattice, giving rise to Néel temperatures that are significantly below 10 K. Comparisons are made with other characterized [FeCl₄]^? compounds having similar organic base cations, enabling clarification of the superexchange mechanism.     

THE EPR SPECTRA OF TETRADENTATE SCHIFF BASE COMPLEXES OF COPPER (II) I. N,N'-Bis-(acetylacetone) ethylenediimine and N,N'-Bis-(1,1,1-trifluoroacetylacetone) ethylenediimine

Abstract

The EPR spectrum of N, N'-bis-(acetylacetone)ethylenediimino Cu(II), [Cu-en(acac)₂], and N, N'-bis-(1,1,1-trifluoroacetylacetone)ethylenediimino-Cu(II), [Cu-en(tfacac)₂], have been studied in doped single crystals of the corresponding Ni(II) chelate. The parameters in the usual doublet spin-Hamiltonian are found to be: Cu[en(acac)₂], g_z =2.183 ± 0.003, g_x =2.047 ± 0.004, g_y =2.048 ± 0.004, A_z =204.8 × 10^?4cm^?1, A_x =31.5 × 10^?4cm^?1, A_y =27.1 × 10^?4 cm^?1, A_zN= 12.8 × 10^?4 cm^?1 and A_xN =A_yN =14.3 × 10^?4 cm^?1: Cu[en(tfacac)₂], g_z =2.192 ± 0.002, g_x =2.048 ± 0.004, g_y =2.046 ± 0.004, A_z =200.8 × 10^?4 cm^?1, A_x =31.1 × 10^?4 cm^?1, A_y =28.3 × 10^?4 cm^?1, A_zN =12.8 × 10^?4 cm^?1 and A_xN =A_yN =14.6 × 10^?4 cm^?1. These parameters are related to coefficients in the molecular orbitals of the complex. It is found that the α-bonding is quite covalent and there is significant in-plane σ-bonding. From the nitrogen hyperfine structure it is determined that the hybridization on the nitrogen is sp².     

The Stabilities and Thermodynamic Properties of Manganese(II) and Nickel(II) Chelates of Trans-1,2-Diaminocyclohexane-N,N, N', N'-Tetraacetic Acid

The interaction between trans-1,2-diaminocyclohexane-N, N, N', N'-tetraacetic acid (H₁DCTA or H₄Z) and Mn(II) and Ni(II) ions has been investigated. The formation constants of the hydrogen chelates (MHZ^?), and of the normal chelates (MZ^2?), have been measured at 20, 30 and 40°C, and an ionic strength of 0.10 (KNO₃). The former was done by a titration technique and the latter by a mercury indicator electrode method. Enthalpy and entropy changes characterizing the formation of the normal chelates have been calculated at 25°C.     

Neue Lithiumchlorid-Suzukiphasen: Li6MCl8(M = Fe,Co, Ni)

Novel Lithium Chloride Suzuki Phases, Li₆MCl₈ (M = Fe, Co, Ni) The hitherto unknown Suzuki phases Li₆FeCl₈, Li₆CoCl₈, and Li₆NiCl₈ ( cF 60) were prepared by fusing the binary chlorides. X-ray, DTA, and conductivity data as well as the infrared and Raman spectra are presented. The unit cell dimensions of the cubic (space group Fm3 m) halides are a = 1029.3, 1027.5, and 1023.5 pm, respectively. Li₆FeCl₈ and Li₆CoCl₈ undergo a reversible phase transition to disordered LiCl solid solutions at 275 and 355°C, respectively. The metastable nickel compound can only be prepared by quenching from about 560°C. The lithium chloride Suzuki phases are fast lithium ion conductors at elevated temperatures. The specific conductivities are 1.4 × 10^?1, 1.5 × 10^?1, and 6.9 × 10^?2Ω^?1 × cm^?1 at 500°C, respectively. Whereas the i.r. spectra of the Suzuki phases only reveal a broad band, the Raman spectra exhibit the four group theoretically allowed modes as sharp scattering peaks, which are discussed in terms of the vibrational modes of this structure.     

Das unterschiedliche Reaktionsverhalten von basefreiem Tris(trimethylsilyl)methyl‐Lithium gegenüber den Trihalogeniden der Erdmetalle und des Eisens

The Variable Reaction Behaviour of Base‐free Tris(trimethylsilyl)methyl Lithium with Trihalogenides of Earth‐Metals and Iron Base‐free tris(trimethylsilyl)methyl Lithium, Tsi–Li, reacts with the earth‐metal trihalogenides (MHal₃ with M = Al, Ga, In and Hal = Cl, Br, I) primarily to give the metallates [Tsi–MHal₃]Li. Simultaneous to this simple metathesis a methylation also takes place, mainly with heavier halogenides of Ga and In with excess Tsi–Li, forming the mono and dimethyl compounds Tsi–M(Me)Hal (M = Ga, In; Hal = I), Tsi–MMe₂ (M = Ga), and the bis(trisyl)derivative (Tsi)₂InMe, respectively and the main by‐product 1,3‐disilacyclobutane. Representatives of each type of compound have been isolated by fractionating crystallizations or sublimations and characterized by spectroscopic methods (¹H, ¹³C, ²⁹Si NMR, IR, Raman) and X‐ray elucidations. Reduction takes place, when FeCl₃ reacts with Tsi–Li (1 : 3 ratio) in toluene at 55–60 °C, yielding red‐violet Fe(Tsi)₂, 1,1,1‐tris(trimethylsilyl)‐2‐phenyl ethane and low amounts of Tsi–Cl. Fe(Tsi)₂ is monomeric, crystallizes in the monoclinic space group C2/c and consists of a linear C–Fe–C skeleton with d(Fe–C) of 204,5(4) pm.     

STRUCTURAL,MAGNETOCHEMICAL, SPECTRAL AND THERMAL PROPERTIES OF TRANS-TETRAKIS(1,2-DIAZOLE) BISBROMOMANGANESE(II)

Abstract

The crystal structure of trans-tetrakis(1,2-diazole)bisbromomanganese(II) was solved by direct methods using single-crystal X-ray (Mo-Kα) diffractometer data and refined to R = 0.054 for 1270 unique reflections with I > 2Δ(I). The compound crystallized from water as almost colourless, monoclinic prisms in space group C2/c (No. 15) with unit cell dimensions a = 14.208(2), b = 9.454(1), c = 15.015(3)Å,β = 118.68(1)°, Z = 4. The structure is formed from [(C₃H₄N₂)₄(Br)₂Mn] molecular units held together through stacking of the 1.2-diazole rings approximately in the b-direction and weak van der Waals forces and hydrogen bonds. The coordination sphere around the Mn²⁺ ion is weakly distorted octahedral with two pairs of trans-positioned 1,2-diazole molecules at distances Mn-N(1) = 2.246(7) and Mn-N(3) = 2.229(6) Å, respectively, in the basal plane and the Br^? ions occupying the apical positions at a distance Mn-Br(1) = 2.729(1)Å. The angles Br(1)-Mn-N(1), Br(1)-Mn-N(3) and N(1)-Mn-N(3) are 91.2(1). 89.6(1) and 87.8(2)°. respectively. The 1,2-diazole rings are practically planar, but slightly tilted (N(1) and N(3) containing rings are at angles of 89.9(3) and 86.4(3)° with respect to the basal coordination plane). The molecular units form columns in the b-direction. The molar magnetic susceptibilities, corrected for diamagnetism by Pascals constants, at 93–303 K show the compound to be of high-spin complex type with a Curie-Weiss equation X'_M = 4.30/(T-3.3) and the reflectance spectrum in accordance with this shows only a very weak shoulder at 23500 cm^?1 corresponding to the ⁶A_1g ± ⁴T_2g transition for the Mn²⁺ ion. The infrared spectrum shows an Mn-Br band at 715 and Mn-N bands at 680, 600 and 580 cm^?1. The thermogravimetric (TG) curve shows the complex to release the 1,2-diazole molecules in two steps in accordance with the structure.     

Tris[bis(trimethysilyl)amido]zinkate von Lithium und Calcium

Tris[bis(trimethylsilyl)amido]zincates of Lithium and Calcium Calcium-bis[bis(trimethylsilyl)amide] and Bis[bis(trimethylsilyl)amido]zinc yield in 1,2-dimethoxyethane quantitatively Calcium-bis{tris[bis(trimethylsilyl)- amido]zincate} · 3DME. When THF is chosen as a solvent, the two reactants and the zincate form a temperature-independent equilibrium, whereas in benzene no reaction occurs. The tris[bis(trimethylsilyl)amido]zincate anion displays characteristic ¹³C{¹H) and ²⁹Si{¹H] chemical shifts of 7 and ?8 ppm, respectively; the nature of the solvent, the cation and the complexating ligands don't influence the IR nor NMR data of the zincate anion and thus verify that [Ca(DME)₃]²⁺ and {Zn[N(SiMe_{3 2}]₃}^? appear as solvent separated ions, which is also confirmed by their insolubility in hydrocarbons.     

Die Reaktionen von Eisen(III)-chlorid mit Trithiazylchlorid. Die Kristallstruktur von [S4N4Cl]+[FeCl4]⊖

Reactions of Iron Trichloride with Trithyazyl Chloride. Crystal Structure of [S₄N₄Cl]⁺[FeCl₄]^? Iron trichloride reacts with (NSCl)₃ yielding S₄N₄[FeCl₄]₂, S₃N₃Cl₂[FeCl₄] or S₄N₄Cl[FeCl₄], depending on the reaction conditions. The i.r. spectra prove the presence of [FeCl₄]^? ions for all three compounds. The ⁵⁷Fe-Mössbauer spectra show a slight quadrupole splitting at 80 K for S₃N₃Cl₂[FeCl₄] (ΔE^Q = 0.42 mm · s^?1) and S₄N₄Cl[FeCl₄] (ΔE^Q = 0.23 mm · s^?1), which indicates a slight deformation of the FeCl₄^? tetrahedra. The crystal structure of S₄N₄Cl[FeCl₄] was determined and refined with X-ray diffraction data (2549 independent reflexions, R = 0.026). S₄N₄Cl[FeCl₄] crystallizes in the triclinic space group P1 with two formula units per unit cell. The lattice constants are a = 712, b = 911, c = 1006 pm, α = 76.5°, β = 83.8° and γ = 80.5°. The structure consists of the so far unknown [S₄N₄Cl]^⊕ cations and slightly deformed FeCl₄^? ions. The [S₄N₄Cl]^⊕ ion consists of a S₄N₄ ring built up of two nearly planar S₃N₂ fragments having a dihedral angle of 136°. The average SN bond length is 157 pm, the SCI bond length 214 pm.     

THE EPR SPECTRA OF TETRADENTATE SCHIFF BASE COMPLEXES OF COPPER (II) II. N,N'-bis(salicylidene)ethylenediimine and 7-methyl-N,N'-bis (salicylidene)ethylenediimine

Abstract

The EPR spectra of single crystals of ⁶³Cu(II) doped N, N'-bis(salicylidene)ethylenediimine Ni(II), [Ni(sal)₂en] and 7-methyl-N, N'-bis(salicylidene)ethylenediimine Ni(II), [Ni(7-me sal)₂en] have been studied. The usual doublet spin-Hamiltonian parameters for the complexes have been found to be: Cu(II)[(sal)₂en]; g _z =2.192 ± 0.002; g _x =2.046 ± 0.004; g _y =2.049 ± 0.004; A _z =201.0 × 10^?4 cm^?1; A _x =29.3 × 10^?4 cm^?1; A _y =31.3 × 10^?4 cm^?1; A^N _z =12.6 × 10^?4 cm^?1; A ^N _x =14.5 × 10^?4 cm^?1; A ^N _y =15.7 × 10^?4 cm^?1; A ^H _z =6.3 × 10^?4 cm^?1; A ^H _x =7.3 × 10^?4 cm^?1; A ^H _y =7.9 × 10^?4 cm^?1; Cu(II)[(7-me sal)₂en]; g _z =2.189 ± 0.002; g _x =2.037 ± 0.004; g _y =2.046 ± 0.004; A _z =203.0 × 10^?4 cm^?1; A _x =36.9 × 10^?4 cm^?1; A _y =22.7 × 10^?4 cm^?1; A ^N _z =12.6 × 10^?4 cm^?1; A ^N _x =13.3 × 10^?4 cm^?1; A ^N _y =14.0 × 10^?4 cm^?1. Values of molecular orbital coefficients calculated for these complexes show that their bonding properties are similar to those of other compounds of this type. There is considerable covalency in the metal-ligand [sgrave]-bonds, and significant in-plane pi-bonding is present.     

Tetrakis(triphenylphosphaniminato)tantalonium-hexachlorotantalat, [Ta(NPPh3)4]TaCl6. Synthese,IR-Spektrum,Kristallstruktur und Ab-initio-Rechnungen am [Ta(NPH3)4]+-Ion

Tetrakis(triphenylphosphane-iminato)tantalonium hexachlorotantalate, [Ta(NPPh₃)₄]TaCl₆. Synthesis, IR Spectrum, Crystal Structure, and ab initio Calculations of the [Ta(NPH₃)₄]⁺ Ion The title compound has been prepared by the reaction of tantalum pentachloride with Me₃SiNPPh₃ in acetonitrile, forming colourless moisture sensitive crystals, which were characterized by IR spectroscopy and by an X-ray structure determination (Space group P1 , Z = 4, 6479 observed unique reflections, R = 0.053. Lattice dimensions at 20°C: a = 1268.4(3), b = 2361.0(6), c = 2400.0(6) pm, α = 85.81(2)°, β = 87.47(3)°, γ = 87.27(3)°). The compound consists of two symmetry-independent cations [Ta(NPPh₃)₄]⁺ and anions TaCl₆^?, respectively. In the cations the tantalum atoms are surrounded in a distorted tetrahedral fashion by the four nitrogen atoms of the phosphane-iminato ligands. The TaN and PN bond lengths in both individuals correspond well with double bonds. According to twisting phenomena of the phenyl rings the TaNP bond angles are different in the two cation species. The investigation is supplemented by ab initio calculations of the [Ta(NPH₃)₄]⁺ ion.     

Synthesis,spectroscopic characterization,and X-ray crystal structure of tris(trimethylsilyl)cyanurate

Tris(trimethylsilyl)cyanurate, C₁₂H₂₇N₃O₃Si₃ (1), has been synthesized and characterized by elemental analysis, IR, Raman, ¹³C and ²⁹Si NMR, and thermogravimetric methods. The molecular and crystal structure has been determined by single crystal X-ray diffraction. This compound crystallized in space group P6₃/m (176), Z = 2 with a = 11.017(2), b = 11.017(2), c = 9.676(3) Å; α = 90°, β = 90°, γ = 120°. The geometry of the molecule is compared with tris(trimethylsilyl)cyamelurate.     

Synthese und Kristallstruktur von dimerem Dipyrazoldipyrazolato-platin(II), [Pt(pz)2(Hpz)2]2

Synthesis and Crystal Structure of Dimeric Dipyrazole Dipyrazolato Platinum(II), [Pt(pz)₂(Hpz)₂]₂ The dimeric complex [Pt(pz)₂(Hpz)₂]₂ (Hpz = pyrazole) is obtained in water from [Pt(Hpz)₄]²⁺ and OH^? or pz^?. The colorless compound is insoluble in water. It decomposes at 191°C to form Pt(pz)₂. [Pt(pz)₂(Hpz)₂]₂ crystallizes in the monoclinic space group C2/c with the lattice constants a = 2 165.5, b = 972,0, c = 1 648.4 pm, β = 123.09°, Z = 4. Each Pt²⁺ ion is coordinated in a square-planar arrangement by two Hpz molecules and two pz^? anions. The dimeric complex is formed by four symmetrical N? H? N bridges between the Hpz and pz^? ligands of both Pt atoms causing a complete charge delocalization between the ligands. The complex has the symmetry C₂ with two of the bridging H atoms lying on the symmetry axis. The Pt? N distances of 200 pm correspond to covalent single bonds. v(NH) is observed as broad absorption at 2 400 cm^?1.     

Synthesis,Structural Characterization,and Cation Transport of Tripotassium Pentabismuth Arsenate K3Bi5(AsO4)6

During the exploration of the K₂O-Bi₂O ₃ -As₂O₅ system, single crystals of a new arsenate of trivalent bismuth, K₃Bi₅(AsO₄) ₆, were isolated by solid state reaction at 600°C. The title compound crystallizes in the monoclinic system, space group C2/c (N°15) with a = 18.257(2) Å, b = 7.260(1) Å, c = 20.130(4) Å, β = 119.86(1)°, and Z = 4. Its structure consists of a three-dimensional framework made up of AsO₄ tetrahedra and BiO₆ and BiO₇ polyhedra sharing edges and corners, delimiting cavities wherein K⁺ ions reside. This compound exhibits a potassium ion conductivity but with rather low conductivity value.     

Mössbauer study of quenched Fe(III) salt solutions

The Mössbauer spectra of quenched aqueous iron(III) salt solutions containing HClO₄, H₂SO₄, HCl, respectively, were measured. The magnetic hyperfine structure of the spectra was studied as a function of the change of acid and iron concentrations. In the solutions of FeCl₃ containing 8.5N HCl we suppose the presence of octahedral [FeCl₄(H₂O)₂]^? complex.     

PPh4{MoNCI3[N(SiMe3)2]}, ein Nitrido-Amido-Komplex von MoIybdän(VI)

Inhaltsübersicht. PPh₄{MoNCl₃[N(SiMe₃)₂]} entsteht aus PPh₄[MoNCl₄] und N,N,N′-Tris-(trimethylsilyl)benzamidin in siedendem Dichlormethan in Form bernsteinfarbener Kristalle, die wir IR-spektroskopisch und durch eine röntgenographische Strukturanalyse charakterisiert haben. Raumgruppe P2₁/n, Z = 4, R = 4,3% für 5168 unabhängige beobachtete Reflexe. Die Gitterkonstanten betragen für ?65°C: A = 918,9; b = 2850,5; c = 1353,9 pm; β = 107,51°. Die Verbindung besteht aus PPh₄⁺-Ionen und Anionen [MoNCl₃[N(SiMe₃)₂]}^–, in denen das Molybdänatom verzerrt tetragonal-pyramidal von dem Nitridoliganden in Apical-Position (r MoN = 165 pm), von drei Chloratomen und von dem N-Atom des Bis(trimethylsilyl)amido-Liganden (r MoN = 194 pm) umgeben ist. Das N-Atom des Amido-Liganden besitzt eine planare Umgebung. PPh₄{MoNCl₃[N(SiMe₃)₂]}, a Nitrido Amido Complex of Molybdenum (VI) PPh₄{MoNCl₃[N(SiMe₃)₂}] has been prepared by the reaction of PPh₄[MoNCl₄] with N,N,N′-Tris(trimethylsilyl)benzamidine in boiling dichloromethane, forming amber coloured crystals, which were characterized by their IR spectrum as well as by an X-ray structure determination. Space group P2₁/n, Z = 4, R = 0.043 for 5168 observed independent reflexions. The lattice dimensions are at ?65°C: A = 918.9; b = 2850.5; c = 1353.9 pm; β = 107.51°. The compound consists of PPh₄⁺ ions and anions {MoNCl₃[N(SiMe₃)₂]}^– in which the complex molybdenum anion forms a distorted tetragonal pyramid with the nitrido ligand (r MoN 165 pm) in the apical position and the chlorine atoms along with the nitrogen atom of the amido ligand (r MoN 194 pm) in the basical positions. The N atom of the amido ligand has a planar geometry.     

Structural and physico-chemical characteristics of tetraethylammonium tetrachloridoferrate(III)

The crystal structure of tetraethylammonium tetrachloridoferrate(III) was determined. The crystals are hexagonal, space group P6₃ mc, a = 8.198(1) Å, b = 8.198(1) Å, c = 13.183(3) Å, V = 767.3(2) Å³, Z = 2. The asymmetric unit of [(C₂H₅)₄N][FeCl₄] consists of half each of a tetraethylammonium cation and a tetrachloridoferrate(III) anion. Tetrachloridoferrate(III) ion adopts almost ideal tetrahedral geometry. Structural characterization of the compound is supplemented by the results of its magnetic susceptibility measurements and electron paramagnetic resonance (EPR) spectra. Magnetic measurements of a powdered [(C₂H₅)₄N][FeCl₄] sample gave a negative Weiss constant of ?1.57, which suggests antiferromagnetic coupling. The susceptibility curve of [(C₂H₅)₄N][FeCl₄] against temperature exhibits a maximum, indicating the presence of antiferromagnetic ordering with a Neel temperature of approximately 2.9 K.     

Acyl- und Alkylidenphosphane. XXVII [I.]. Molekül- und Kristallstruktur des Methyl[(N-phenyl,N-tri-methylsilyl)thiocarbamoyl]trimethylsilylphosphans

Acyl- and Alkylidenephosphines. XXVII. Molecular and Crystal Structure of Methyl-[(N-phenyl, N-trimethylsilyl)thiocarbamoyl]trimethylsilylphosphine . Methyl[(N-phenyl, N-trimethylsilyl)thiocarbamoyl]trimethylsilylphosphine 1a formed via an addition of methylbis(trimethylsilyl)phosphine to phenyl isothiocyanate [1], crystallizes in the monoclinic centrosymmetric space group P2₁/n with following dimensions of the unit cell determined at a temperature of measurement of ?80±3°C: a=1041.2(4);b=1706.9(12);c=1001.1(6)pm; β=106.41(4)°; Z = 4. An X-ray structure determination (R_w = 0.039) confirms the constitution of the compound as already derived from its nmr spectra. One trimethylsilyl group is bound to the phosphorus atom, whereas the other is connected with the sp²-hybridized nitrogen atom. Characteristic rounded bond lenghts and angles are: P? Si 231, P? CH₃ 184, P? C(S) 187, C?S 167, N? C(S) 137, and N? Si 181 pm as well as P? C? S 122°, P? C? N 117°, and S? C? N 121°.     

Synthesis and crystal structure of bis(dibenzo-18-crown-6)cesium tetrachloroferrate(III)

A new complex [Cs(Db18C6)₂]⁺[FeCl₄]^? was prepared and studied by X-ray diffraction (orthorhombic, space groupP2₁2₁2,a = 22.934 Å,b= 24.024 Å,c= 16.665 Å,Z= 8; direct method, anisotropic full-matrix least-squares refinement,R= 0.087 for all 8800 independent reflections; CAD4 automated diffractometer, λMoK _α. Two independent [FeCl₄]^? anions have a slightly distorted tetrahedral structure. Two independent host-guest type complex cations [Cs(Db18C6)₂]⁺ have a sandwich structure. The Cs⁺ cation is located between two Db18C6 crown ligands below and above the centers of their 18-membered macrocycles and is coordinated by all 12 O atoms. The coordination polyhedron of Cs⁺ (C.N. 12) is a distorted hexagonal antiprism rotated toward a hexagonal prism.     

(Dibenzo-18-crown-6)potassium tetrachloroferrate(III): Synthesis and crystal structure

A new complex [K(Db18C6)]⁺[FeCl₄]^? (I) is synthesized and its structure is studied by X-ray diffraction analysis. The crystals are triclinic: space group P \(\bar 1\), a = 17.998, b = 18.670, c = 19.590 Å, α = 106.61°, β = 104.55°, γ = 113.87°, Z = 8. The structure is solved by a direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.057 by 13 670 independent reflections (CAD-4 automated diffractometer, λMoK _α). All the four independent complex cations [K(Db18C6)]⁺ are host-guest, and in each complex cation the K⁺ cation is localized in the cavity of the Db18C6 crown ligand. The coordination polyhedron of K⁺ (coordination number nine) is a distorted hexagonal bipyramid with the base of all six O atoms of the Db18C6 ligand, the axial vertex at the Cl atom of the [FeCl₄]^? anion, and another bifurcated axial vertex at two Cl atoms of another [FeCL₄]^? anion. All the four independent [FeCL₄]^? anions are orientationally disordered and have somewhat distorted tetrahedral structure. In crystal I, the alternating complex cations [K(Db18C6)]⁺ and [FeCL₄]^? anions form infinite polymer chains by the K-Cl bonds.     

Sulfophthalide cycle cleavage and formation of fluorenyl structures upon poly(diphenylene sulfophthalide) thermolysis

Thermolysis of poly(diphenylene sulfophthalide) (PDSP) in the temperature range from 100 to 500 °C was studied by IR and UV-Vis spectroscopy and thermogravimetric analysis. A series of absorption bands in the IR spectrum of PDSP were assigned on the basis of the theoretical calculations of the IR spectrum of diphenyl sulfophthalide used as a model compound, in particular, ν_as(S=O) = 1352 cm^?1, ν_s(S=O) = 1196 cm^?1, ν(C-O) ～ 920 cm^?1, ν(S-O) = 824 cm^?1, and δ(SO₂) = 576 cm^?1. The sulfophthalide cycle (SPC) in PDSP decomposes at the thermolysis temperatures in a range of 260–400 °C. An analysis of the IR spectra of the thermolyzate and the quantum chemical calculations of the IR spectra of the model compounds confirmed the predominant formation of fluorenyl structures in the thermolyzed polymer. The changes in the UV-Vis spectra observed upon the thermolysis of thin films of PDSP (the hypsochromic shift of the long-wavelength absorption band from 271 to 263 nm and the appearance a shoulder at ～310 nm) and the results of TD-DFT calculations of the UV-Vis spectra of the model compounds are consistent with the hypothesis about the formation of fluorenyl structures. The general scheme of PDSP thermolysis at 260–400 °C was proposed in which the major process is the formation of fluorenyl fragments in macromolecules of the polymer due to the intramolecular ring closure in biradicals formed by the SPC cleavage.