Darstellung und spektroskopische Charakterisierung von Bindungsisomeren Halogenoselenocyanatoosmaten(IV)

Preparation and Spectroscopic Characterization of Bondisomeric Halogenoselenocyanatoosmates (IV) The new compounds [OsCl₅(NCSe)]^2?, [OsCl₅(SeCN)]^2?, tr.-[OsCl₄(NCSe)(SeCN)]^2?, tr.-[OsCl₄I(NCSe)]^2? and tr.-[OsCl₄I(SeCN)]^2? are prepared from [OsCl₅I]^2? and tr.-[OsCl₄I₂]^2? by oxidative ligand exchange with (SeCN)₂ or by reaction with suspended Pb(SeCN)₂ in CH₂Cl₂ and isolated by ion exchange chromatography on DEAE cellulose. The bondisomers are significantly distinguished by the frequencies of innerligand vibrations: ν_CN(Se), ν_CN(N), ν_CSe(N) > ν_CSe(Se), δ_NCSe >, δ_SeCN. The electronic spectra measured at 10 K on the solid salts exhibit in the region 450–650 nm intensive Se → Os and N → Os charge transfer bands. Essentially weaker intraconfigurational transitions (t) are observed near to 2000 and 1000 nm, splitted by lowered symmetry (C_4v) and spin orbit coupling. Only some of the 0–0-transitions may be assigned by measuring electronic Raman bands with the same frequencies.     

Kristallstrukturen und Normalkoordinatenanalyse der bindungsisomeren Pentachloroselenocyanatorhenate (IV)

Crystal Structure and Normal Coordinate Analysis of Linkage Isomeric Pentachloroselenocyanatorhenates (IV) The X-ray structure determinations on single crystals of (Ph₃PNPPh₃)₂[ReCl₅(NCSe)] ( 1 ) (monoclinic, space group P2₁/n, a = 10.806(2), b = 13.349(2), c = 46.071(4) Å, β = 94.947(9)°, Z = 4) and (Py₂CH₂)[ReCl₅(SeCN)] ( 2 ) (monoclinic, space group P2₁/n, a = 12.044(1), b = 9.838(1), c = 15.686(2) Å, β = 105.913(8)°, Z = 4) reveal, that the nearly linear selenocyanate group (178°) is coordinated via N with the Re–N–C angle of 172.7 ( 1 ) and via Se with the Re–Se–C angle of 107.4° ( 2 ). Based on the molecular parameters of the X-ray determinations the IR and Raman spectra, known from literature for both linkage isomers, have been assigned by normal coordinate analysis. The valence force constants are f_d(ReN) = 1.72 and f_d(ReSe) = 1.20 mdyn/Å.     

Darstellung und spektroskopische Charakterisierung von bindungsisomeren Halogenorhodanoosmaten(IV)

Preparation and Spectroscopic Characterization of Bond-Isomeric Halogenorhodanoosmates(IV) By oxidation of tr.-[OsCl₄BrI]^2? or tr.-[OsCl₄I₂]^2? with (SCN)₂ in CH₂Cl₂, by substitution of [OsCl₅I]^2? with SCN^? or [OsCl₅(NCS)]^2? with F^? in toluene and by reaction of [OsF₅Cl]^2? with (SCN)₂ in CH₂Cl₂ the following bondisomers are prepared: tr.-[OsF₄Cl(NCS)]^2?/tr.-[OsF₄Cl(SCN)]^2?, tr.-[OsFCl₄(NCS)]^2?/tr.-[OsFCl₄(SCN)]^2?, tr.-[OsCl₄Br(NCS)]^2?/tr.-[OsCl₄Br(SCN)]^2?, tr.-[OsCl₄I(NCS)]^2?/tr.-[OsCl₄I(SCN)]^2?,tr.-[OsCl₄(NCS)₂]^2?/tr.-[OsCl₄(NCS)(SCN) ]^2?/tr.-[OsCl₄(SCN)₂]^2?, [OsBr₅(NCS)]^2?/[OsBr₅(SCN)]^2? and tr.-[OsBr₄(NCS)(SCN)]^2?. All complexes are isolated as pure compounds by ion exchange chromatography on DEAE-cellulose. In the IR and Raman spectra ν_CN(S), ν_CS(N) and δ_NCS are found at higher wave numbers than ν_CN(N), ν_CS(S) and δ_SCN. According to spin orbit coupling and to lowered symmetry (D_4h, C_4v) the splitted intraconfigurational transitions are observed at 10 K as weak bands in the regions 600, 1000, 2000 nm. The O? O transitions are calculated from vibrational fine structure and in some cases are confirmed by electronic Raman bands with the same frequencies. The energy niveaus deduced with ζ(Os^IV) = 3200 cm^?1 and the calculated Racah parameters B are in good agreement with the barycenters of the observed multiplets for D_4h and C_4v symmetry.     

Darstellung,Kristallstruktur und Normalkoordinatenanalyse der bindungsisomeren Pentachlororhodanoosmate(IV)

Preparation, Crystal Structure and Normal Coordinate Analysis of Linkage Isomeric Pentachlororhodanoosmates(IV) By treatment of [OsCl₅I]^2? with (SCN)₂ in dichloromethane the linkage isomers [OsCl₅(NCS)]^2? and [OsCl₅(SCN)]^2? are formed which have been separated by ion exchange chromatography on diethylaminoethyl cellulose. The X-ray structure determination on single crystals of (Ph₄As)₂[OsCl₅(NCS)] (monoclinic, space group P2₁/a, a = 18.872(2), b = 11.6024(2), c = 22.786(1), β = 109.057(1)°, Z = 4) and (Ph₄As)₂[OsCl₅(SCN)] (monoclinic, space group P2₁/a, a = 19.057(2), b = 11.306(2), c = 22.612(1), β = 106.64(2)°, Z = 4) reveals the complete ordering of the complex anions. The thiocyanate group is located above one of the Cl ligands of the equatorial plane with the Os? N? C angle of 166.1° for N bonding and the Os? S? C angle of 109.9° for S bonding. The IR and Raman spectra of both linkage isomers known from literature are assigned by normal coordinate analysis based on the general valence force field using the molecular parameters of the X-ray determination. The valence force constants are f_d(OsN) = 1,81 and f_d(OsS) = 1,32 mdyn/Å. Taking into account increments of the trans influence a good adjustment between observed and calculated frequencies is achieved.     

Darstellung,Kristallstrukturen, Schwingungsspektren und Normalkoordinatenanalyse von vier bindungsisomeren Tetrachlorodirhodanoosmaten(IV)

Preparation, Crystal Structures, Vibrational Spectra, and Normal Coordinate Analysis of Four Linkage Isomeric Tetrachlorodirhodanoosmates(IV) By treatment of cis- or trans-[OsCl₄I₂]^2? with (SCN)₂ in dichloromethane the linkage isomers cis-[OsCl₄(NCS)₂]^2? ( 1 ), trans-[OsCl₄(NCS)(SCN)]^2? ( 2 ), cis-[OsCl₄(NCS)(SCN)]^2? ( 3 ) and trans-[OsCl₄(SCN)₂]^2? ( 4 ) are formed which have been separated by ion exchange chromatography on diethylaminoethyl cellulose. The X-Ray structure determinations on single crystals of cis-(Ph₄As)₂[OsCl₄(NCS)₂] (triclinic, space group P1 , a = 10.019(5), b = 11.702(5), c = 21.922(5) Å, α = 83.602(5)°, β = 85.718(5)°, γ = 73.300(5)°, Z = 2), trans-(Ph₄As)₂[OsCl₄ · (NCS)(SCN)] (monoclinic, space group P2₁/c, a = 18.025(5), b = 11.445(5), c = 23.437(5) Å, β = 94.208(5)°, Z = 4), cis-(Ph₄As)₂[OsCl₄(NCS)(SCN)] (triclinic, space group P1 , a = 10.579(5), b = 11.682(5), c = 22.557(5) Å, α = 81.073(5)°, β = 85.807(5)°, γ = 87.677(5)°, Z = 2) and trans-(Ph₄As)₂ · [OsCl₄(SCN)₂] (triclinic, space group P1 , a = 10.615(5), b = 11.691(5), c = 11.907(5) Å, α = 111.314(5)°, β = 96.718(5)°, γ = 91.446(5)°, Z = 1) reveal the complete ordering of the complex anions. The via N or S coordinated thiocyanate groups are located nearly direct above one of the cis-positioned Cl ligands with Os? N? C angles of 171.2° and 174.3° ( 1 ), 162.3° ( 2 ), 172° ( 3 ) and Os? S? C angles of 108.3° ( 2 ), 105.7° ( 3 ) and 105.5° ( 4 ). 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 linkage isomers are assigned by normal coordinate analyses based on a modified valence force field. The valence force constants are f_d(OsN) = 1.59 ( 1 ), 1.67 ( 2 ), 1.60 ( 3 ) and f_d(OsS) = 1.27 ( 2 ), 1.31 ( 3 ) and 1.32 mdyn Å^?1 ( 4 ). Taking into account increments of the trans influence a good agreement between observed and calculated frequencies is achieved.     

Darstellung,spektroskopische Charakterisierung und Normalkoordinatenanalyse der bindungsisomeren Tetrachloroiodoselenocyanatoosmate(IV). Kristallstruktur von trans‐(PPh4)2[OsCl4I(NCSe)]

Preparation, Crystal Structure, and Normal Coordinate Analysis of Linkage Isomeric Pentachloroiodoselenocyanatoosmates(IV). Crystal Structure of trans‐(PPh₄)₂[OsCl₄I(NCSe)] By treatment of the solution of (n‐Bu₄N)₂[OsCl₅I] in dichloromethane with suspended Pb(SeCN)₂ the linkage isomers trans‐(n‐Bu₄N)₂[OsCl₄I(NCSe)] ( 1 ) and trans‐(n‐Bu₄N)₂[OsCl₄I(SeCN)] ( 2 ) are formed, which have been separated by ion exchange chromatography on diethylaminoethyl cellulose. The X‐Ray structure determination on a single crystal of trans‐(PPh₄)₂[OsCl₄I(NCSe)] (triclinic, space group P1¯, a = 10.8950(13), b = 11.076(2), c = 20.980(2)Å, α = 96.940(10), β = 98.747(9), γ = 104.419(11)°, Z = 2) reveals, that the nearly linear selenocyanate group in trans position to the iodine atom is coordinated with the Os‐N‐C angle of 171.1°. Based on the molecular parameters of the X‐ray determination ( 1 ) and estimated data ( 2 ) the IR and Raman spectra of both linkage isomers are assigned by normal coordinate analysis. The valence force constants are f_d(OsN) = 1.70 und f_d(OsSe) = 1.15 mdyn/Å.     

Darstellung,Kristallstrukturen, Schwingungsspektren und Normalkoordinatenanalyse von vier bindungsisomeren Trichlorotrirhodanoosmaten(IV)

Preparation, Crystal Structures, Vibrational Spectra, and Normal Coordinate Analysis of four Linkage Isomeric Trichlorotrirhodanoosmates(IV) By treatment of fac-[OsCl₃I₃]^2? with (SCN)₂ in dichloromethane the linkage isomers fac-[OsCl₃(NCS)₃]^2? ( 1 ), mer-[OsCl₃(NCS)₂^c(SCN)]^2? ( 2 ), mer-[OsCl₃(NCS)(SCN)₂^t]^2? ( 3 ), and mer-[OsCl₃(NCS)(SCN)₂^c]^2? ( 4 ) are formed which have been separated by ion exchange chromatography on diethylaminoethyl cellulose. X-Ray structure determinations have been performed on single crystals of fac-(Ph₄As)₂[OsCl₃(NCS)₃] (triclinic, space group P1 , a = 12.142(5), b = 13.233(5), c = 19.300(5) Å, α = 98.642(5)º, β = 100.509(5)º, γ = 112.514(5)º, Z = 2), mer-(Ph₄As)₂[OsCl₃(NCS)₂^c (SCN)] · acetone (triclinic, space group P1 , a = 11.707(5), b = 13.238(5), c = 19.048(5) Å, α = 75.960(5)º, β = 88.981(5)º, γ = 69.999(5)º, Z = 2), mer-(Ph₄As)₂[OsCl₃(NCS)(SCN)₂ ^t] (triclinic, space group P1, a = 10.6861(12), b = 11.6587(5), c = 12.5232(5) Å, α = 112.069(8)º, β = 95.052(8)º, γ = 92.559(7)º, Z = 1) and mer-(Ph₄As)₂[OsCl₃(NCS)(SCN)₂ ^c] · 2acetone (triclinic, space group P1 , a = 11.444(5), b = 14.661(5), c = 15.830(5) Å, α = 75.790(5)º, β = 80.273(5)º, γ = 75.205(5)º, Z = 2). The complex anions are completely ordered. The via N or S coordinated thiocyanate groups are located nearly direct above one of the cis-positioned Cl ligands with Os? N? C angles of 169.1º, 171.5º, 175.7º ( 1 ), 175.6º, 178.6º ( 2 ), 172º ( 3 ), and 173.1º ( 4 ) and Os? S? C angles of 106.2º ( 2 ), 106.1º, 106.6º ( 3 ), 105.1º, and 108.2º ( 4 ). 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 linkage isomers have been assigned by normal coordinate analyses based on a modified valence force field. The valence force constants are f_d(OsN) = 1.71 ( 1 ), 1.46 and 1.62 ( 2 ), 1.69 ( 3 ), and 1.61 ( 4 ), f_d(OsS) = 1.27 ( 2 ), 1.36 ( 3 ), 1.32, and 1.49 mdyn/Å ( 4 ). Taking into account increments of the trans influence a good agreement between observed and calculated frequencies is achieved.     

Kristallstrukturen und Schwingungsspektren von Tetrahalogenoacetylacetonatoosmaten(IV), [OsX4(acac)]−, X  Cl,Br, I

Crystal Structures and Vibrational Spectra of Tetrahalogenoacetylacetonatoosmates(IV), [OsX₄(acac)]^?, X ? Cl, Br, I By reaction of the hexahalogenoosmates(IV) with acetylacetone the tetrahalogenoacetylacetonatoosmates(IV) [OsX₄(acac)]^? (X = Cl, Br, I) are formed, which have been purified by chromatography and precipitated from aqueous solution as tetraphenylphosphonium (Ph₄P) or cesium salts. X-ray structure determinations on single crystals have been performed of (Ph₄P)[OsCl₄(acac)] ( 1 ) (triclinic, space group P1 , a = 9.9661(6), b = 11.208(2), c = 13.4943(7) Å, α = 101.130(9), β = 91.948(6), γ = 96.348(8)°, Z = 2), (Ph₄P)[OsBr₄(acac)] ( 2 ) (monoclinic, space group P2₁/n, a = 9.0251(8), b = 12.423(2), c = 27.834(2) Å, β = 94.259(7)°, Z = 4) and (Ph₄P)[OsI₄(acac)] ( 3 ) (monoclinic, space group P2₁/c, a = 18.294(3), b = 10.664(2), c = 18.333(3) Å, β = 117.68(2)°, Z = 4). Due to the increasing trans influence in the series O < Cl < Br < I the Os? O^. distances of O^.? Cl? X′ axes are lengthened and the OsO^. stretching vibrations are shifted to lower frequencies. The Os? X′ bond lenghts are shorter as compared with symmetrically coordinated X? Os? X axes.     

Darstellung,Kristallstruktur, Schwingungsspektren und Normalkoordinatenanalyse von K2[OsCl5(CO)] · H2O

Synthesis, Crystal Structure, Vibrational Spectra, and Normal Coordinate Analysis of K₂[OsCl₅(CO)] · H₂O The X-ray structure determination of K₂[OsCl₅(CO)] · H₂O (monoclinic, space group P2₁/c a = 13.600(2), b = 7.122(1), c = 22.186(11) Å, β = 98.66(3)°, Z = 8) revealed two crystallographic independent bat very similar complex anions [OsCl₅(CO)]^2? with rough C_4v point symmetry. Due to the stronger trans influence of the carbonyl group the bond lengths in the Cl? Os? CO axis Os? Cl = 2.449(2), 2.430(2) Å are langer as compared with the octahedron basis Os? Cl = 2.340-2.370 Å. The water of crystallization is coordinated to potassium (K? OH₂ = 2.625-2.815 Å). Using the molecular parameters the IR and Raman spectra are assigned by normal coordinate analysis. The valence force constants are f_d(CO) = 15.30, f_d(OsC) = 3.88, f_d(OsCl) = 1.81, f_d(OsCl) = 1.36, f_d(OH) = 7.65, 7.82, 7.79 mdyn/Å. The strengthening of the Os? C bond by stronger back donation of the Os^III(d⁵) complex in comparison with the isostructural Os^IV (d⁴) compound is discussed.     

Darstellung und spektroskopische Charakterisierung der reinen Bindungsisomeren [OsCl5(NCS)]2− und [OsCl5(SCN)]2−

Preparation and Spectroscopic Characterization of the Pure Bondisomers [OsCl₅(NCS)]^2? and [OsCl₅(SCN)]^2? The oxidation of [OsCl₅I]^2? with (SCN)₂ in CH₂Cl₂ yields the bondisomers [OsCl₅(NCS)]^2? and [OsCl₅(SCN)]^2?, which are isolated as pure compounds by ion exchange chromatography on DEAE-Cellulose. Only the salts of the N-isomer show significant shifts in the vibrational and electronic spectra caused by polarization of the terminal S depending on the size of the cations and the polarity of the solvents. In the IR and Raman spectra ν_CN(S), ν_CS(N) and δ_NCS are found at higher wave numbers than ν_CN(N), ν_CS(S) and δ_SCN. In the optical spectrum of the red [OsCl₅(SCN)]^2? the charge-transfer S→Os is nearly constant at 538 nm, but the N→Os transition of the yellow to violet coloured N-isomer shifts from 480 nm in organic solvents or in presence of large alkylammonium cations to 516 nm in aqueous solution and to 544 nm in the solid Cs-salt. The optical electronegativities are calculated to χ_opt(–SCN) = 2.6 and χ_opt(–NCS) = 2.6–2.8. According to spinorbit coupling and to lowered symmetry (C_4v) the splitted intraconfigurational transitions are observed at 10 K as weak peaks in the regions 600, 1000 and 2000 nm. The O? O transitions are calculated from the vibrational fine structure. The lowest level of both isomers is confirmed by peaks in the electronic raman spectra. With the parameters ζ(Os^IV) = 3200 cm^?1 and B(? SCN) = 316 cm^?1 or B(? NCS) = 288 cm^?1 there is a good fit of calculated and experimental data, resulting in the nephelauxetic series: F^? > CI^? > SCN^? > Br^? > NCS^? > I^?.     

Darstellung und Charakterisierung der Pentammin-Komplexe [Os(NH3)5(NCS)]2+ und [Os(NH3)5(NCSe)]2+

Preparation and Characterization of the Pentammine Complexes [Os(NH₃)₅(NCS)]²⁺ and [Os(NH₃)₅(NCSe)]²⁺ The new pentammine complexes [Os(NH₃)₅(NCS)]²⁺ and [Os(NH₃)₅(NCSe)]²⁺ are prepared from the reaction of [Os(NH₃)₅(CF₃SO₃)](CF₃ SO₃)₂ with NH₄SCN and KSeCN, respectively, in acetone, and subsequent purification by ion exchange chromatography on carboxymethyl cellulose. Evidence of N-bonding in both cases is given by the vibrational spectra, indicating that Os³⁺ is in terms of Lewis acidity harder than Ru³⁺, Rh³⁺, and Ir³⁺. I.r. and Raman spectra are interpreted according to local C_4v symmetry around Os, and the presumed assignments are confirmed by comparison with the i.r. spectra of the perdeuterated compounds. In the electronic spectra of both complexes charge transfer bands at 412 nm (NCS) and 498 nm (NCSe) are observed, respectively. Further weak absorptions near 4500 and 5100 cm^?1, which are in correlation with electronic Raman bands, are assigned to intraconfigurational transitions within the ²T_2g (O_h) ground term, split into three Kramers doubletts by spin-orbit coupling and lowered symmetry. Electrochemical measurements demonstrate a stabilisation of +III and +II oxidation states by π-back donation to —NCS and —NCSe ligands.     

Structural and theoretical studies of (E,E)-benzaldehyde azine and its rhenium(IV) complex

The azine bridged dicatechol ligand (E,E)-benzaldehyde azine (H₄L) was fully characterized by X-ray analysis. The reaction of [ReCl₆]²⁻ with this compound was studied and the novel Re(IV) complex (HNEt₃)(NBu₄)[ReCl₄(H₂L)] was prepared and characterized. The structure and spectroscopy of the compound H₄L and its Re(IV) complex were studied experimentally and by means of density functional calculations.     

Schwingungs-Raman-Spektren von Hexahalogenokomplexen von OsIV (X = Cl,I) und IrIV (X = Cl,Br) bei 80 K

Vibrational Raman Spectra of Hexahalo Complexes of Os^IV (X = Cl, I) and Ir^IV (X = Cl, Br) at 80 K The Resonance-Raman (RR) spectra of the tetrabutyl- resp. tetraethylammonium salts of [OsCl₆]^2?, [OsI₆]^2?, [IrCl₆]^2?, and [IrBr₆]^2? have been investigated with the excitation-lines of an Ar⁺ and Kr⁺ laser. Devices with a movable sample holder for low-temperature experiments (80 K) are described. The anormal intensities of some of the Ra-active fundamentals are attributed to the RR effect. As a rule the deformation vibration υ₅(T_2g) is RR enhanced if excited within a π—π*(dt_2g)-CT-transition and the stretching vibration υ₂(E_g) is RR-enhanced within a π—σ*(de_g)-CT-transition. The dispersion of the degree of depolarisation of the three Ra-active fundamentals of [IrBr₆]^2? demonstrates, that this rule cannot only be applicated to the symmetrical but also to the antisymmetrical part of the scattering tensor.     

Trennung und Charakterisierung von Chloro-aquo-hydroxo-oxo-osmaten(IV)

Separation and Characterization of Chloro-aquo-hydroxo-oxo-osmates(IV) As a result of the acidic hydrolysis of hexachloroosmate(IV), OsCl₆^2?, and/or the careful reduction of osmium tetroxide with iron(II) sulfate in hydrochloric acid products have been obtained which have been separated by column chromatography using diethylaminoethyl cellulose. On the basis of the analytically determined Os:Cl ratios, the ionic charges that could be deduced from the elution behaviour, and the absorption spectra the products have been characterized as the monomers OsCl₅(H₂O)^?, cis-OsCl₄(OH)(H₂O)^?, fac-OsCl₃(OH)₂(H₂O)^? and mer-OsCl₃(OH)(H₂O)₂, the O-bridged dimers Cl₅Os? O? OsCl₅^4?, cis-(H₂O)Cl₄Os? O? OsCl₄(H₂O)^2?and fac-(H₂O)(OH)Cl₃Os? O? OsCl₃(OH)(H₂O)^2? and the hydrogen bridges forming OH-bridged dimers shown in “Inhaltsübersicht”.     

Darstellung,Schwingungsspektren und Normalkoordinatenanalyse von mer-[OsCl3I(NCS)]2− sowie Kristallstrukturanalyse von zwei Modifikationen des mer-(Ph4As)2[OsCl3I(NCS)2c]

Preparation, Vibrational Spectra, and Normal Cooordinate Analysis of mer-[OsCl₃I(NCS)₂^c]^2? and Crystal Structures of two Modifications of mer-(Ph₄As)₂[OsCl₃I(NCS)₂^c] By treatment of cis-/trans-[OsCl₄I₂]^2? or fac-[OsCl₃I₃]^2? with (SCN)₂ in dichloromethane mixtures of different linkage isomers are formed, from which mer-[OsCl₃I(NCS)]^2? has been isolated by ion exchange chromatography on diethylaminoethyl cellulose. With tetraphenylarsonium ions mer-(Ph₄As)₂[OsCl₃I(NCS)₂^c] crystallizes in two different modifications. From acetone solution the high-temperature form α precipitates above ?10°C, the low-temperature form β below, ?65°C. The X-Ray structure determinations on single crystals of α-mer-(Ph₄As)₂[OsCl₃I(NCS)₂^c] (triclinic, space group P 1 , a = 10.245(5), b = 11.690(5), c = 22.027(5) Å, α = 83.650(5)°, β = 85.734(5)°, γ = 72.566(5)°, Z = 2) and β-mer-(Ph₄As)₂[OsCl₃I(NCS)₂^c] (triclinic, space group P 1 , a = 10.959(5), b = 11.122(5), c = 21.745(5) Å, α = 97.677(5)°, β = 92.339(5)°, γ = 104.712(5)°, Z = 2) reveal the ordering of the complex anions, which significantly differ in their geometry. The via N coordinated thiocyanate groups exhibit Os? N? C angles of 172.7° and 173.3° (α) and of 164.4° and 175.4° (β). Using the molecular parameters of the X-Ray determinations the low temperature (10 K) IR and Raman spectra of the (n-Bu₄N) salt of the complex anion are assigned by a normal coordinate analysis based on a modified valence force field. The valence force constants are f_d(OsN) = 1.66 and 1.64 mdyn/Å. Taking into account the trans influence a good agreement between observed and calculated frequencies is achieved.     

Schwingungs- und Elektronenspektren der Dekahalogenodiosmate(IV), [Os2X10]2−, X  Cl,Br

Vibrational and Electronic Spectra of Decahalogenodiosmates(IV), [Os₂X₁₀]^2?, X ? Cl, Br The IR and Raman spectra of the edge-sharing bioctahedral anions [Os₂X₁₀]^2?, X ? Cl, Br, are assigned according to point group D_2h. The bands are found in three characteristic regions; at high wavenumbers stretching vibrations with terminal ligands v(OsCl_t): 365–280, v(OsBr_t): 235–195; in a middle region with bridging ligands v(OsCl_b): 270–240, v(OsBr_b): 175–165 cm^?1; the deformation bands are observed at distinct lower frequencies. The electronic spectra of the dimers show intraconfigurational transitions near 2000, 1000, and 600 nm which by position and intensity correspond to those of the monomeric complexes. They are therefore discussed separately for both metal centers according to C_2v symmetry. Two additional band systems are presumable pair transitions arising from interactions of the central ions within the dimeric complexes. Due to the different bonding strength of terminal or bridging ligands the intensive charge transfer bands are shifted by 3000–4000 cm^?1 bathochromicly or by 2000–3000 cm^?1 hypsochromicly compared with the hexahaloosmates(IV).     

Kristallstrukturen,Schwingungsspektren und Normalkoordinatenanalysen von (n-Bu4N)2[ReBr5(NCS)] und (n-Bu4N)2[ReBr5(NCSe)]

Crystal Structures, Vibrational Spectra, and Normal Coordinate Analysis of ( n -Bu₄N)₂[ReBr₅(NCS)] and ( n -Bu₄N)₂[ReBr₅(NCSe)] The X-ray structure determinations on single crystals of (n-Bu₄N)₂[ReBr₅(NCS)] ( 1 ) (monoclinic, space group P2₁/n, a = 10.9860(9), b = 11.6860(7), c = 35.551(3) Å, β = 91.960(9)°, Z = 4) and (n-Bu₄N)₂[ReBr₅(NCSe)] ( 2 ) (monoclinic, space group P2₁/n, a = 11.0208(15), b = 11.7418(16), c = 35.621(12) Å, β = 92.003(18)°, Z = 4) reveal that the thiocyanate and the selenocyanate group are bonded with the Re–N–C angle of 168.5° ( 1 ) and 169.9° ( 2 ). Based on the molecular parameters of the X-ray determinations the IR and Raman spectra have been assigned by normal coordinate analysis. The valence force constants f_d(ReN) are 1.81 ( 1 ) and 1.75 mdyn/Å ( 2 ).     

Magneto-structural study on a series of rhenium(IV) complexes containing biimH2, pyim and bipy ligands

Three rhenium(IV) mononuclear compounds of formulae [ReCl₄(biimH₂)] · 2DMF (1), [ReCl₄(pyim)] · DMF (2) and [ReCl₄(bipy)] (3) (biimH₂ = 2,2′-biimidazole, pyim = 2-(2′-pyridyl)imidazole, bipy = 2,2′-bipyridine and DMF = N,N-dimethylformamide) have been prepared and characterized. The crystal structure of 2 was determined by single crystal X-ray diffraction. Compound 2 crystallizes in the monoclinic system with P2₁/c as space group. The rhenium atom is six-coordinated by four Cl atoms and two nitrogen atoms from a bidentate pyim ligand [average values of Re–Cl and Re–N bonds lengths being 2.330(2) and 2.117(4) Å, respectively]. The magnetic properties were investigated from susceptibility measurements performed on polycrystalline samples of 1–3 in the temperature range 1.9–300 K. The magnetic behaviour found is typical of antiferromagnetically coupled systems, and they exhibit susceptibility maxima at 2.8 (1 and 2) and 5.6 K (3). Short Re^IV–Cl?Cl–Re^IV contacts through space account for the antiferromagnetic behaviour observed.     

Synthese und spektroskopische Charakterisierung von [Rh(SeCN)6]3– und trans‐[Rh(CN)2(SeCN)4]3–, Kristallstruktur von (Me4N)3[Rh(SeCN)6]

Synthesis and Spectroscopic Characterization of [Rh(SeCN)₆]^3– and trans ‐[Rh(CN)₂(SeCN)₄]^3–, Crystal Structure of (Me₄N)₃[Rh(SeCN)₆] Treatment of RhCl₃ with KSeCN in acetone yields a mixture of selenocyanato‐rhodates(III), from which [Rh(SeCN)₆]^3– and trans‐[Rh(CN)₂(SeCN)₄]^3– have been isolated by ion exchange chromatography on diethylaminoethyl cellulose. The X‐ray structure determination on a single crystal of (Me₄N)₃[Rh(SeCN)₆] (trigonal, space group R3, a = 14.997(2), c = 24.437(3) Å, Z = 6) reveals, that the compound crystallizes isotypically to (Me₄N)₃[Ir(SCN)₆]. The exclusively via Se coordinated selenocyanato ligands are bonded with the average Rh–Se distance of 2.490 Å and the Rh–Se–C angle of 104.6°. In the low temperature IR and Raman spectra the metal ligand stretching modes ν(RhSe) of (n‐Bu₄N)₃[Rh(SeCN)₆] ( 1 ) and trans‐(n‐Bu₄N)₃[Rh(CN)₂(SeCN)₄] ( 2 ) are in the range of 170–250 cm^–1. In 2 ν_as(CRhC) is observed at 479 cm^–1. The vibrational spectra are assigned by normal coordinate analysis based on the molecular parameters of the X‐ray determination. The valence force constants are f_d(RhSe) = 1.08 ( 1 ), 1.10 ( 2 ) and f_d(RhC) = 3.14 mdyn/Å ( 2 ). f_d(RhS) = 1.32 mdyn/Å is determined for [Rh(SCN)₆]^3–, which has not been calculated so far. The ¹⁰³Rh NMR resonances are 2287 ( 1 ), 1680 ppm ( 2 ) and the ⁷⁷Se NMR resonances are –32.7 ( 1 ) and –110.7 ppm ( 2 ). The Rh–C bonding of the cyano ligand in 2 is confirmed by a dublett in the ¹³C NMR spectrum at 136.3 ppm.     

Photochemischer Ligandenaustausch an Hexahalogenoosmaten(IV)

Photochemical Ligand Exchange of Hexahalo Osmates(IV) Irradiation of hexahaloosmates(IV) in various polar solvents (H₂O, CH₃CN, C₅H₅N) gives preferable monosubstituted products. First time [OsCl₅(NC? CH₃)]^?, [OsBr₅(NC? CH₃)]^? and [OsCl₅py]^? are prepared photochemically in larger amounts. The quantum yields in the region 313–436 nm are 10^?2–10^?3. The photochemical stability of the mono-substituted products is discussed. By photolysis of [OsBr₆]^2? in CH₂Cl₂ and 1,2-C₂H₄Cl₂ the mixed-ligand complexes [OsCl_nBr_6–n]^2? are formed. After ionophoretic separation for the species with n = 2, 3, 4 a statistical ratio of the stereoisomers is observed. Slow photosubstitution takes place too in alkali halide pellets of the complex salts at room temperature.