The ratio of excimer to monomer emission in diesters of 1-pyrenoic acid and five glycols

The ratio of the intensities of excimer and monomer emission, I_D/I_M, has been measured for Py? COO? (CH₂)_m? OOC? Py (m = 2–6, Py = 1-pyrenyl) in solvents of different viscosity, η. These compounds are dimeric models for the corresponding polymers, selected to eliminate the influence of energy migration on the population of an excimer. The solvents are H(CH₂)_nOH, n = 1–7, and ethylene glycol. The values of I_D/I_M decrease as η increases, and the rate of this decrease is a function of m. Therefore the qualitative dependence of I_D/I_M on m is a function of η. In the limit as η → ∞, I_D/I_M is an odd–even function of m for m = 2–5, and the values at m = 5 and 6 are nearly identical. A rotational-isomeric state analysis of the conformations of the diesters can rationalize the appearance of the odd–even effect. This result is insensitive to assumptions about the extent of overlap of the two pyrene ring systems that is required for the production of emission in the excimer band. © 1993 John Wiley & Sons, Inc.     

Intramolecular excited state complexes in trichromophoric model compounds for polyesters derived from 2,6‐naphthalenedicarboxylic acid and aliphatic glycols: experiment,rotational isomeric state model,and molecular dynamics

Steady‐state fluorescence was used to measure the ratio of emission intensities, denoted I_D/I_M, for excited state complexes and excited monomers of five trichromophoric compounds, 2‐naphthyl‐COO‐(CH₂)_m‐OOC‐2,6‐dinaphthyl‐COO‐(CH₂)_m‐OOC‐2‐naphthyl, m = 2–6. The linear aliphatic alcohols H(CH₂)_nOH, n = 1–7, as well as mixtures of ethylene glycol and methanol, were used to change the viscosity of the medium, η. The values of I_D/I_M depend on η and m. A Rotational Isomeric State model and Molecular Dynamics simulations were used for interpretation of the experimental results. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 253–266, 1999     

Effect of the directionality of the ester group on the formation of hairpins in polyesters containing naphthalene and a flexible spacer

Steady-state fluorescence measurements and molecular dynamics simulations have been used to study the intramolecular formation of excimers in five model compounds for polyesters containing naphthalene groups separated by flexible spacers. The model compounds are derived from 2-hydroxynaphthalene and HOOC (CH₂)_n COOH, n = 2–6. The ratio of the intensity of excimer and monomer emissions, I_D/I_M, is nearly independent of the viscosity of the medium, η, over the range covered in dilute solution. Although I_D/I_M is always very small, it shows an odd–even effect for the first four members of the series, with maxima when n is odd. Molecular dynamics simulations provide an explanation for the small values of I_D/I_M, their weak dependence on η, and the trend of I_D/I_M with n. The results for the present series of model compounds are compared with previous work, which reported larger values of I_D/I_M, and a stronger dependence of I_D/I_M on η, for bichromophoric compounds derived from 2-naphthoic acid and aliphatic glycols, where the direction of the ester groups is reversed. The origin of the difference in the behavior of I_D/I_M in the two series is identified. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1127–1133, 1997     

Moderately concentrated solutions of polystyrene. I. Viscosity as a function of concentration,temperature, and molecular weight

Data on the viscosity η of moderately concentrated solutions of polystyrene are reported. Several solvents were investigated, including cyclopentane solutions over a temperature span between θ_U = 19.5°C and θ_L = 154.5°C. The data were analyzed in terms of a relation giving η as a function of αφM, where α_φ is the expansion factor for the chain dimensions in a solution with volume fraction φ of polymer with molecular weight M. It is shown that values of α_φ so determined decrease as ? lnα_φ/? lnφ = (1 ? 2μ)/6μ for φ greater than φ^* = 0.2M/s³ for moderately concentrated solutions, where s is the root-mean-square radius of gyration and μ = ? ln[η]/? lnM with [η] the intrinsic viscosity.     

Synthesis and thermoresponsive property of end‐functionalized poly(N‐isopropylacrylamide) with pyrenyl group

N–Isopropylacrylamide (NIPAM) was polymerized using 1‐pyrenyl 2‐chloropropionate (PyCP) as the initiator and CuCl/tris[2‐(dimethylamino)ethyl]amine (Me₆TREN) as the catalyst system. The polymerizations were performed using the feed ratio of [NIPAM]₀/[PyCP]₀/[CuCl]₀/[Me₆TREN]₀ = 50/1/1/1 in DMF/water of 13/2 at 20 °C to afford an end‐functionalized poly(N‐isopropylacrylamide) with the pyrenyl group (Py–PNIPAM). The characterization of the Py–PNIPAM using matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry provided the number–average molecular weight (M_n,MS). The lower critical solution temperature (LCST) for the liquid–solid phase transition was 21.7, 24.8, 26.5, and 29.3 °C for the Py–PNIPAMs with the M_n,MS's of 3000, 3400, 4200, and 5000, respectively; hence, the LCST was dramatically lowered with the decreasing M_n,MS. The aqueous Py–PNIPAM solution below the LCST was characterized using a static laser light scattering (SLS) measurement to determine its molar mass, M_w,SLS. The aqueous solutions of the Py–PNIPAMs with the M_n,MS's of 3000, 3400, 4200, and 5000 showed the M_w,SLS of 586,000, 386,000, 223,000, and 170,000, respectively. Thus, lowering the LCST for Py–PNIPAM should be attributable to the formation of the PNIPAM aggregates. The LCST of 21.7 °C for Py–PNIPAM with the M_n,MS of 3000 was effectively raised by adding β‐cyclodextrin (β‐CD) and reached the constant value of ～26 °C above the molar ratio of [β‐CD]/[Py–PNIPAM] = 2/1, suggesting that β‐CD formed an inclusion complex with pyrene in the chain‐end to disturb the formation of PNIPAM aggregates, thus raising the LCST. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1117–1124, 2006     

Influence of Isotope Substitution on Lattice and Spin‐Peierls‐Type Transition Features in One‐Dimensional Nickel Bis‐dithiolene Spin Systems

Four new 1D spin‐Peierls‐type compounds, [D₅]1‐(4′‐R‐benzyl)pyridinium bis(maleonitriledithiolato)nickelate ([D₅]R‐Py; R=F, I, CH₃, and NO₂), were synthesized and characterized structurally and magnetically. These 1D compounds are isostructural with the corresponding non‐deuterated compounds, 1‐(4′‐R‐benzyl)pyridinium bis(maleonitriledithiolato)nickelate (R‐Py; R=F, I, CH₃, and NO₂). Compounds [D₅]R‐Py and R‐Py (R=F, I, CH₃, and NO₂) crystallize in the monoclinic space group P2₁/c with uniform stacks of anions and cations in the high‐temperature phase and triclinic space group P$\bar 1$ with dimerized stacks of anions and cations in the low‐temperature phase. Similar to the non‐deuterated R‐Py compounds, a spin‐Peierls‐type transition occurs at a critical temperature for each [D₅]R‐Py compound; the magnetic character of the 1D S=1/2 ferromagnetic chain for [D₅]F‐Py and the 1D S=1/2 Heisenberg antiferromagnetic chain for others appear above the transition temperature. Spin‐gap magnetic behavior was observed for all of these compounds below the transition temperature. In comparison to the corresponding R‐Py compound, the cell volume is almost unchanged for [D₅]F‐Py and shows slight expansion for [D₅]R‐Py (R=I, CH₃, and NO₂) as well as an increase in the spin‐Peierls‐type transition temperature for all of these 1D compounds in the order of F>I≈CH₃≈NO₂. The large isotopic effect of nonmagnetic countercations on the spin‐Peierls‐type transition critical temperature, T_C, can be attributed to the change in ω₀ with isotope substitution.     

Equilibrium,kinetics, and mechanism of the malonic acid–iodine reaction

The equilibrium constant for the reaction CH₂(COOH)₂ + I₃^? ? CHI(COOH)₂ + 2I^? + H⁺, measured spectrophotometrically at 25°C and ionic strength 1.00M (NaClO₄), is (2.79 ± 0.48) × 10^?4M². Stopped-flow kinetic measurements at 25°C and ionic strength 1.00M with [H⁺] = (2.09-95.0) × 10^?3M and [I^?] = (1.23-26.1) × 10^?3M indicate that the rate of the forward reaction is given by (k₁[I₂] + k₃[I₃^?]) [HOOCCH₂COO^?] + (k₂[I₂] + k₄[I₃^?]) [CH(COOH)₂] + k₅[H⁺] [I₃^?] [CH₂(COOH)₂]. The values of the rate constants k₁-k₅ are (1.21 ± 0.31) × 10², (2.41 ± 0.15) × 10¹, (1.16 ± 0.33) × 10¹, (8.7 ± 4.5) × 10^?1M^?1·sec^?1, and (3.20 ± 0.56) × 10¹M^?2·sec^?1, respectively. The rate of enolization of malonic acid, measured by the bromine scavenging technique, is given by k_en[CH₂(COOH)₂], with k_en = 2.0 × 10^?3 + 1.0 × 10^?2 [CH₂(COOH)₂]. An intramolecular mechanism, featuring a six-member cyclic transition state, is postulated to account for the results on the enolization of malonic acid. The reactions of the enol, enolate ion, and protonated enol with iodine and/or triodide ion are proposed to account for the various rate terms.     

The Periodate‐Based Double Perovskites M2NaIO6 (M = Ca,Sr, and Ba)

The crystal structures of the M₂NaIO₆ series (M = Ca, Sr, Ba), prepared at 650 °C by ceramic methods, were determined from conventional laboratory X‐ray powder diffraction data. Synthesis and crystal growth were made by oxidizing I^– with O₂^(air) to I⁷⁺ followed by crystal growth in the presence of NaF as mineralizator, or by the reaction of the alkali‐metal periodate with the alkaline‐earth metal hydroxide. All three compounds are insoluble and stable in water. The barium compound crystallizes in the cubic space group Fm3m (no. 225) with lattice parameters of a = 8.3384(1) Å, whereas the strontium and calcium compounds crystallize in the monoclinic space group P2₁/c (no. 14) with a = 5.7600(1) Å, b = 5.7759(1) Å, c = 9.9742(1) Å, β = 125.362(1)° and a = 5.5376(1) Å, b = 5.7911(1) Å, c = 9.6055(1) Å, β = 124.300(1)°, respectively. The crystal structure consists of either symmetric (for Ba) or distorted (for Sr and Ca) perovskite superstructures. Ba₂NaIO₆ contains the first perfectly octahedral [IO₆]^5– unit reported. The compounds of the ortho‐periodates are stable up to 800 °C. Spectroscopic measurements as well as DFT calculations show a reasonable agreement between calculated and observed IR‐ and Raman‐active vibrations.     

The synthesis and crystal structure of a trinuclear molybdenum cluster compound [Mo3(μ-O)(μ-S)3(μ(μ-OAc)2(dtp)2·(Py)]·0.5H2O

[Mo₃,OS₃(dtp)₄(H₂O)] reacts with NaOAc·3H₂O in Py to give the title compound. The crystal data are as follows: [Mo₂OS₃)(OAc)₂(dtp)₂·Py]?0.5H,O(dtp = [S₃P(OC₂H₅)₂]^?, Py = C₅H₅N); M = 976.64; triclinic; space group P1 ; a=11.704(5), b=14.169(7), c= 11.688 (5) Å α=109.94(4) β = 91.53(4), γ = 91.93(4)°; V= 1819(1) Ų; Z=2; D_c = 1.78 g·cm^?3 λ(Mo Kα) = 0.71069 Å μ=15.15 cm^?1; F(000) = 970 T=296 K; final R=0.071 for 1652 reflections with I>3σ(I). In the molecule, the [Mo₃OS₃] core is surrounded by two bridging OAc groups and two terminal chelate dtp groups attached to the {Mo₃} triangle in a symmetric style, and the Py ligand is coordinated to the Mo atom at the apex of {Mo₃} triangle with the nitrogen. This novel configuration is obtained for the first time with Mo—N bond length being 2.27 (2) Å and three Mo—Mo bond lengths 2.584 (4), 2.587 (4) and 2.657(4) Å, respectively. As a whole, the molecule has a virtual C₂ symmetry.     

Kinetics and rate constants for the reaction of tri-n-butylgermanium hydride with methyl iodide and carbon tetrachloride. The combination of methyl and trichloromethyl radicals in solution.

The kinetics of the photoinitiated reductions of methyl iodide and carbon tetrachloride by tri-n-butylgermanium hydride in cyclohexane at 25°C have been studied and absolute rate constants have been measured. Rate constants for the combination of CH₃? and CCl₃? radicals are equal within experimental error and are also equal to the values found for the self-reactions of most non-polymeric radicals in low viscosity solvents, i.e. ～1–3 × 10⁹ M^?1 sec^?1. Rate constants for hydrogen atom abstraction by CH₃? and CCl₃? radicals are both ～1?2 × 10⁵ M^?1 sec^?1. Tri-n-butyltin hydride is about 10–20 times as good a hydrogen donor to alkyl radicals as is tri-n-butylgermanium hydride. The strength of the germanium–hydrogen bond, D(n-Bu₃Ge–H) is estimated to be approximately 84 kcal/mole.     

Ultra‐high molecular weight poly(ε‐caprolactone) by means of diphenyl bismuth bromide

Diphenyl bismuth bromide (Ph₂BiBr) allows for polymerizations of ε‐caprolactone in bulk at temperatures as low as 40 °C. Time conversion curves indicate a lower reactivity than tin(II) 2‐ethyl hexanoate (SnOct₂) plus alcohol at 120 °C and also at 60 °C. Ph₂BiBr also proved to be less reactive than Ph₂BiOEt, but more reactive than BiBr₃ and Bi(III)n‐hexanoate. Small amounts (≤1 wt %) of cyclic oligoester were detectable by MALDI‐TOF mass spectrometry even at a polymerization temperature of 40 °C. The molar masses depend on the monomer–initiator ratio (M/I) but not in a simple parallel manner. With M/I = 600/1 number average molecular weights (M_ns, corrected values) around 500 kDa were obtained. Even at low M/Is high molar mass polylactones were found and CH₂Br endgroups were not detectable. However, upon addition of tetra(ethylene glycol) the coinitiator was completely incorporated yielding telechelic polylactones and the molar mass increased with the monomer–coinitiator ratio. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 851–859, 2008     

Pressure dependence of the viscosity of dilute polystyrene solutions in toluene

The effect of pressure on the viscosity of dilute solutions of anionically polymerized polystyrene (M?_w = 209,000; M_w/M_n = 1.12) in toluene has been studied at different temperatures and concentrations using a falling-body viscometer. Measurements were performed in the concentration range from 0.0025 to 0.02 g/mL and at temperatures from 25 to 45°C under pressure up to 1057 bars. The viscosity coefficient η increases exponentially with pressure at a given temperature and concentration, while the apparent volume of activation V^? decreases with increasing temperature. The hypothesis that the pressure dependence of η is given by the pressure dependence of the activation energy holds true under the prevailing thermodynamic conditions. Log η increases linearly with increasing concentration at a given pressure. Intrinsic viscosity increases with increasing pressure, whereas the Huggins constant decreases.     

1‐(β‐d‐Erythrofuranosyl)adenosine

The title compound, also known as β‐erythroadenosine, C₉H₁₁N₅O₃, (I), a derivative of β‐adenosine, (II), that lacks the C5′ exocyclic hydroxymethyl (–CH₂OH) substituent, crystallizes from hot ethanol with two independent molecules having different conformations, denoted (IA) and (IB). In (IA), the furanose conformation is ^OT₁–E₁ (C1′‐exo, east), with pseudorotational parameters P and τ_m of 114.4 and 42°, respectively. In contrast, the P and τ_m values are 170.1 and 46°, respectively, in (IB), consistent with a ²E–²T₃ (C2′‐endo, south) conformation. The N‐glycoside conformation is syn (+sc) in (IA) and anti (−ac) in (IB). The crystal structure, determined to a resolution of 2.0 Å, of a cocrystal of (I) bound to the enzyme 5′‐fluorodeoxyadenosine synthase from Streptomyces cattleya shows the furanose ring in a near‐ideal ^OE (east) conformation (P = 90° and τ_m = 42°) and the base in an anti (−ac) conformation.     

Crystal structure and magnetic properties of a nitronyl nitroxide complex {[Co2(NIT4Py)4(fum)2(H2O)4] · (H2O)2} n

The title compound {[Co₂(NIT4Py)₄(fum)₂(H₂O)₄] · (H₂O)₂} _n , where NIT4Py = 2-(4′-pyridinyl)-4,4,5,5-tetra-methylimidazoline-1-oxyl-3-oxide and fum = fumarate, was prepared and structurally characterized by X-ray diffraction. It crystallizes in triclinic, space group P 1 with a = 9.8853(9) Å, b = 13.2167(13) Å, c = 13.8481(12) Å, α = 68.5400(10)°, β = 73.467(2)°, γ = 74.596(2)°, V = 1587.6(3) ų, Z = 1, and R ₁ [I > 2σ(I)] = 0.0662. The complex consists of two kinds of neutral infinite 1-D chains, in which [Co(NIT4Py)₂(H₂O)₂] moieties are connected by fumarate anions in a bis-monodentate mode. These 1-D chains are further connected by hydrogen bonds, generating a 2-D network. The variable temperature magnetic susceptibility measurement reveals that the magnetic couplings between Co(II) and NIT4Py are weak antiferromagnetic interactions.     

Cationic,Methylene‐Bridged,Intramolecular Donor‐Acceptor Systems Based on Zirconium and Hafnium and Phosphino‐methanides

A new access to cationic zirconium and hafnium compounds [L₂MCH₂PR₂][MeB(C₆F₅)₃] (L = Cp, Ind; R = iso‐Pr, tert‐Bu; M = Zr, Hf) exhibiting an intramolecular donor‐acceptor system was established by treating the precursors L₂M(Me)CH₂PR₂ with B(C₆F₅)₃ (BCF). Precursors 1 – 6 [L₂M(Me)CH₂PR₂ with L = Cp, Ind; R = iso‐Pr, tert‐Bu; M = Zr, Hf] were fully characterized. The crystal structures of these compounds revealed large M–CH₂–P bond angles with values of about 134° indicating the absence of interactions between the Lewis‐acid and Lewis‐base. The cationic compounds [L₂MCH₂PR₂][MeB(C₆F₅)₃] ( 7 – 12 ) were obtained by treatment of 1 – 6 with BCF. They were characterized by NMR spectroscopy, mass spectrometry, and elemental analyses; in H/D‐scrambling experiments with H₂/D₂ mixtures 7 – 12 disclosed their reactivity towards cleavage of hydrogen.     

Crystal structure of 4-n-nonylbenzoic acid

The title compound, 4-n-nonylbenzoic acid, CH₃(CH₂)₈C₆H₄COOH (NBA), has been characterized thus: triclinic, P1, a = 13.514(4)Å, b = 23.4672(5)Å, c = 7.658(3)Å, alpha = 90.914(3)°, beta = 100.403(3)°, gamma = 77.781(2)°, V = 2334(2)ų, Z = 2, and F.W = 745.06, D_m = 1.161 g cm^-3, D_c = 1.061 g cm^-3, F₀₀₀ = 816.00, lambda = 0.71069Å, mu = 0.6 cm^-1, goodness-of-fit is 1.029, final R1 = 0.063 and wR2 = 0.16.     

Synthesis,Crystal Structure,and Optical Properties of (CH3NH3)2CoX4 (X = Cl,Br, I,Cl0.5Br0.5, Cl0.5I0.5, Br0.5I0.5)

The reaction of methylammonium halides and cobalt halides yielded the organic‐inorganic hybrid compounds of general formula (CH₃NH₃)₂CoX₄. By varying the different halides, we were able to synthesize the whole row from Cl to I as well as some mixed halides compounds and to determinate the crystal structures. (CH₃NH₃)₂CoX₄ (X = Cl, Br, Cl_0.5Br_0.5, Br_0.5I_0.5) crystallize isotypic to (CH₃NH₃)₂HgCl₄ in space group P2₁/c with Z = 4 [X = Cl: a = 7.6483(9), b = 12.6885(18), c = 10.8752(12) Å, β = 96.639(9)°; X = Cl_0.5Br_0.5: a = 7.8271(9), b = 12.9543(9), c = 11.1007(11) Å, β = 96.320(8)°; X = Br: a = 7.9782(2), b = 13.1673(2), c = 11.2602(2) Å, β = 96.3260(10)° and X = Br_0.5I_0.5: a = 8.2435(12), b = 13.645(2), c = 11.5856(18) Å, β = 95.54(2)°]. The mixed halides show a statistic distribution in both cases. In (CH₃NH₃)₂CoCl₂I₂ an ordered variant is realized representing a new structure type [C2/m, Z = 4, a = 18.808(4), b = 7.3604(7), c = 10.4109(17) Å, β = 120.364(13)°]. (CH₃NH₃)₂CoI₄ crystallizes again isotypic to the respective mercury compound [(CH₃NH₃)₂HgCl₄] [Pbca, Z = 8, a = 10.9265(5), b = 12.1552(5), c = 20.9588(9) Å]. All structures are build up by inorganic tetrahedral [CoX₄]^2– anions and organic (CH₃NH₄)⁺ cations. Additionally the Raman spectra as well as the optical reflectance spectra are discussed.     

Synthesis,light emission,and photovoltaic properties of perylene‐containing polyacetylenes

Perylene (Py)‐containing polyacetylenes with different skeleton structures ? [HC?C(C₆H₄)CO₂? Py]_n? (P 1 ), ? [HC?C(CH₂)₈CO₂? Py]_n? (P 2 ), and ? {[(C₆H₅) C?C(CH₂)₉NH₂]? co? [(C₆H₅)C?C(CH₂)₉? Py]}_n? (P 3 ) are synthesized in satisfactory yields by Rh‐catalyzed polymerization (for P 1 and P 2 ) and polymer reaction (for P 3 ). All the polymers are soluble and possess high molecular weights (M_w up to 2.8 × 10⁵). Their structures and properties are characterized and evaluated by IR, NMR, UV, TGA, PL, and photovoltaic (PV) analyses. The polymers are thermally stable, losing little of their weights when heated to 330 °C. When their solutions are irradiated, their perylene pendants emit intense red fluorescence at 610 nm. PV cells with a configuration of ITO/PEDOT:PSS/polymer/LiF/Al are fabricated, which show maximum current density of 10.3 μA/cm². The external quantum efficiency is sensitive to the polymer structure, with P 3 exhibiting the highest value of 0.23%. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2025–2037, 2008     

Phase separation in mixtures of poly(ethylene glycol monomethylether) and poly(propylene glycol) oligomers

Time-resolved light scattering was employed to investigate kinetics of phase separation in mixtures of poly (ethylene glycol monomethylether) (PEGE)/poly (propylene glycol) (PPG) oligomers. Phase diagrams for PEGE/PPG of varying molecular weights were established by means of cold point measurements. The oligomer mixtures reveal an upper critical solution temperature (UCST). Several temperature quench experiments were carried out with a 60/40 PEGE/PPG blend by rapidly quenching from a single phase (69°C) to two-phase temperatures (66–61°C) at 1°C intervals. As is typical for oligomer mixtures, the early stage of spinodal decomposition (SD) was not detected. The kinetics of phase decomposition was found to be dominated by the late stage of SD. Time-evolution of scattering intensity was analyzed in accordance with nonlinear and dynamical scaling theories. The time dependence of the peak intensity I_m and the corresponding peak wavenumber q_m was found to follow the power-law {I_m(t)? t^α, q_m(t)? t^-β} with the values of α = 3 ± 0.3 and β = 1 ± 0.2, which are very close to the values predicted by Siggia. This process has been attributed to a coarsening mechanism driven by surface tension. In the temporal scaling analysis, the structure function reveals university with time, suggesting self-similarity. Phase separation dynamics in 60/40 PEGE/PPG resembles the behavior predicted for off-critical mixtures.     

Kristallstrukturen,Schwingungsspektren und Normalkoordinatenanalysen der Chloro-Iodo-Rhenate(IV) (CH2Py2)[ReCl5I], cis-(CH2Py2)[ReCl4I2] · 2 DMSO,trans-(CH2Py2)[ReCl4I2] · 2 DMSO und fac-(EtPh3P)2[ReCl3I3]

Crystal Structures, Vibrational Spectra, and Normal Coordinate Analyses of the Chloro-Iodo-Rhenates(IV) (CH₂Py₂)[ReCl₅I], cis -(CH₂Py₂)[ReCl₄I₂] · 2 DMSO, trans -(CH₂Py₂)[ReCl₄I₂] · 2 DMSO, and fac -(EtPh₃P)₂[ReCl₃I₃] [ReCl₅I]^2–, cis-[ReCl₄I₂]^2–, trans-[ReCl₄I₂]^2–, and fac-[ReCl₃I₃]^2– have been synthesized by ligand exchange reactions of [ReI₆]^2– with HCl and are separated by ion exchange chromatography on diethylaminoethyl cellulose. X-ray structure determinations have been performed on single crystals of (CH₂Py₂)[ReCl₅I] ( 1 ) (triclinic, space group P1 with a = 7.685(2), b = 9.253(2), c = 12.090(4) Å, α = 90.06(2), β = 101.11(2), γ = 95.07(2)°, Z = 2), cis-(CH₂Py₂)[ReCl₄I₂] · 2 DMSO ( 2 ) (triclinic, space group P1 with a = 8.662(2), b = 12.109(2), c = 12.9510(12) Å, a = 97.533(11), β = 96.82(2), γ = 89.90(2)°, Z = 2) , trans-(CH₂Py₂)[ReCl₄I₂] · 2 DMSO ( 3 ) (triclinic, space group P1 with a = 9.315(7), b = 9.663(3), c = 15.232(3) Å, α = 80.09(2), β = 81.79(4), γ = 83.99(5)°, Z = 2) and fac-(EtPh₃P)₂[ReCl₃I₃] ( 4 ) (monoclinic, space group P2₁/a with a = 17.453(2), b = 13.366(1), c = 19.420(1) Å, β = 112.132(8)°, Z = 4). The crystal structure of ( 1 ) reveals a positional disorder of the anion sublattice along the asymmetric axis. Due to the stronger trans influence of I compared with Cl on asymmetric axes Cl˙–Re–I′ is caused a mean lenghthening of the Re–Cl˙ distances of 0.020 Å (0.8%) and a shortening of the Re–I′ distances of 0.035 Å (1.3%) with regard to symmetrically coordinated axes Cl–Re–Cl and I–Re–I, respectively. Using the molecular parameters of the X-Ray determinations the low temperature (10 K) IR and Raman spectra of the (n-Bu₄N) salts of all four chloro-iodo-rhenates(IV) are assigned by normal coordinate analyses. The weakening of the Re–Cl˙ bonds and the strengthening of the Re–I′ bonds is indicated by a decrease or increase of the valence force constants each by 9%.