Synthesis and Crystal Structures of Mixed Halophenylbismuthates(III)

Synthesis and characterisation of mixed halophenylbismuthates(III) with a general formula Bu₄N[PhBiX₂Y] where X = Cl or Br; Y = Cl, Br or I; X ≠ Y are reported. The molecular structures of Bu₄N[PhBiCl₂Br] ( 1 ) and Bu₄N[PhBiBr₂I] ( 2 ) are determined by X‐ray crystallography. In mixed halophenylbismuthates, the anion exists as a dimer with bismuth in a distorted square pyramidal coordination. In the dimer the two phenyl groups occupy anti position to each other thereby minimising the repulsion.     

Zu Struktur,Bindung und Ligandenaustauschverhalten von Nitrosyltechnetium(II)-Verbindungen Eine. EPR-Untersuchung

Structure, Bonding, and Ligand Exchange Behaviour of Nitrosyl-Technetium (II) Compounds. An EPR Study EPR investigations on the nitrosyltechnetium(II) compounds (Bu₄N)₂[Tc(NO)Cl₅], (Bu₄N)[Tc(NO)Br₄], (Bu₄N)[Tc(NO)I₄], and (Ph₄As)₂[Tc(NO)(NCS)₅] having a 4 t low-spin configuration are reported. The EPR parameters g?, Ã^Tc as well as ligand hyperfine data are used to analyze the bonding properties. The isotropic parameters g₀ and a are found to be clearly correlated to the composition of the coordination sphere. Therefore, they can be used to characterize mixed-ligand complexes unambiguously. The formation of mixed-ligand complexes was investigated for ligand-exchange reactions on [Tc(NO)Cl₅]^2? and [Tc(NO)Br₄]^?. In these investigations unsaturated dichalcogeno ligands are included.     

Pentachloro-nitridotechnetate(VI), [TcNCl5]2−—an EPR study

By oxidation of nitridotechnetate(V) complexes of the type [TcN(parSS)₂]^0,2? (parSS = diethyldithiocarbamate, diphenyldithiophosphinate and maleonitrile-dithiolate) with chlorine the Tc⁶⁺ complex anion [TcNCl₅]^2? was created and studied by EPR in liquid and frozen solutions. The EPR spectra are in agreement with a d¹ (S = 1/2) system. The hyperfine interactions are used to characterize the bonding properties in the molecular orbital of the unpaired electron.     

PSEUDOTETRAHEDRAL METAL (II) COMPLEXES OF TRIS- (t-BUTYL) PHOSPHINE

Abstract

The synthesis of divalent metal complexes of the type [Bu^t ₃PH] [(Bu^t ₃P)MX₃] (M = Ni; X = Cl, Br, I; M = Co; X = Br; M = Zn; X = Cl) is reported. Characterization of the solids by conductivity, magnetic susceptibility, electronic and vibrational spectral measurements indicate that the structures are similar and unchanged in solution from the solid state. On the basis of an earlier X-ray single crystal analysis of [Bu^t ₃PH] [(Bu^t ₃P)NiBr₃] and a comparison of the physical measurements for the series of complexes, the inner coordination geometry of the anions can be represented as pseudotetrahedral with C_3v local symmetry. The unexpected formation of these ionic complexes is attributed to the bulkiness of tris-(t-butyl) phosphine. The isolation and probable geometry of the anion are also discussed for an orange-brown [Bu^t ₃PH] [Ni(NCS)₃] complex.     

Magnesiumphthalocyanine: Darstellung und Eigenschaften von Halogenophthalocyaninatomagnesat, [Mg(X)Pc2−]− (X = F,Cl, Br); Kristallstruktur von Bis(triphenylphosphin)iminiumchloro(phthalocyaninato)magnesat-Aceton-Solvat

Magnesium Phthalocyanines: Synthesis and Properties of Halophthalocyaninatomagnesate, [Mg(X)Pc^2?]^? (X = F, Cl, Br); Crystal Structure of Bis(triphenylphosphine)iminiumchloro-(phthalocyaninato)magnesate Acetone Solvate Magnesium phthalocyanine reacts with excess tetra(n-butyl)ammonium- or bis(triphenylphosphine)iminiumhalide ((ⁿBu₄N)X or (PNP)X; X = F, Cl, Br) yielding halophthalocyaninatomagnesate ([Mg(X)Pc^2?]^?; X = F, Cl, Br), which crystallizes in part as a scarcely soluble (ⁿBu₄N) or (PNP) complex-salt. Single-crystal X-ray diffraction analysis of ^b(PNP)[Mg(Cl)Pc^2?] · CH₃COCH₃ reveals that the Mg atom has a tetragonal pyramidal coordination geometry with the Mg atom displaced out of the center (Ct) of the inner nitrogen atoms (N_iso) of the nonplanar Pc ligand toward the Cl atom (d(Mg? Ct) = 0.572(3) Å; d(Mg? Cl) = 2.367(2) Å). The average Mg? N_iso distance is 2.058 Å. Pairs of partially overlapping anions are present. The cation adopts a bent conformation (^b(PNP)⁺: d(P1? N(K)) = 1.568(3) Å; d(P2? N(K)) = 1.587(3) Å; ?(P1? N(K)? P2) = 141.3(2)°). Electrochemical and spectroscopic properties are discussed.     

Synthese,EPR und Röntgenkristallstrukturanalyse von mer-Trichloro(2,2′-bipyridin)nitridotechnetium(VI), einem neuen Nitridokomplex des Technetium(VI)

Synthesis, EPR and X-Ray Structure of mer-Trichloro(2,2′-bipyridine)nitridotechnetium(VI) — a new Technetium(VI) Nitrido Complex mer-Trichloro(2,2′-bipyridine)nitridotechnetium(VI) has been prepared by the reaction of (NBu₄)[TcNCl₄] with 2,2′-bipyridine in acetonitrile, whereas the same procedure gives in methanol the technetium(V) cation [TcNCl(bipy)₂]⁺. The EPR spectrum of [TcNCl₃(bipy)] suggests a meridional coordination of the three chloro ligands. [TcNCl₃(bipy)] crystallizes monoclinic in the space group P2₁/n; a = 8.572(1), b = 15.462(1), c = 10.110(1) Å, β = 104.21(1)°, Z = 4. The R value converged at 0.034 on the basis of 3 040 reflections. The technetium atom is distorted octahedrally coordinated with the chloro ligands meridionally cis with respect to the nitrido nitrogen. The Tc? N(1) bond length is 1.669(4) Å, and the Tc? N(3) bond (2.371(4) Å) is significantly lengthened due to the structural trans labilizing influence of the “N^3?” ligand.     

Condensation of CF2Br2, CF2BrCl and BrCF2CF2Br with enamines and ynamines

BrCF₂X (X : Cl, Br, BrCF₂) react wth enamines and ynamines. A radical chain mechanism is proposed. Halogen (Br or Cl) - fluorine exchange of α halodifluoromethylketones to α trifluoromethylketones using Bu₄⁺N, F^?, 3H₂O is examined.     

Formation of nitridotechnetium (VI) μ-oxo dimer complexes with EDTA and EDDA

Reactions of [⁹⁹TcNCl₄]^– with ethylenediaminetetraacetic acid (EDTA) and ethylenediamine-N, N-diacetic acid (EDDA) in a mixture of water and acetone gave Tc^VIN-EDTA and Tc^VIN-EDDA complexes. The infrared spectra of both reaction products showed the existence of the TcN and C=O groups. The elemental analysis indicated the 11 TcN-ligand ratio in the EDTA and EDDA complexes. Electrophoresis showed that the Tc^VI-EDTA complex was an anionic species in a perchlorate solution. For the Tc^VIN-EDDA complex, neutral and anionic species were formed, depending on the pH of the solution. Formation of the -oxo dimer complexes was suggested from the UV-Vis absorption spectra.     

Ruthenium(II)-Phthalocyaninate(2–): Darstellung und Eigenschaften von Acido(carbonyl)phthalocyaninato(2–)ruthenat(II), [Ru(X)(CO)Pc2−]− (X = Cl,Br, I,NCO, NCS,N3)

Ruthenium(II) Phthalocyaninates(2–): Synthesis and Properties of (Acido)(carbonyl)phthalocyaninato(2–)ruthenate(II), [Ru(X)(CO)Pc^2?]^? (X = Cl, Br, I, NCO, NCS, N₃) (ⁿBu₄N)[Ru(OH)₂Pc^2?] is reduced in acetone with carbonmonoxid to blue-violet [Ru(H₂O)(CO)Pc^2?], which yields in tetrahydrofurane with excess (ⁿBu₄N)X acido(carbonyl)phthalocyaninato(2–)ruthenate(II), [Ru(X)(CO)Pc^2?]^? (X = Cl, Br, I, NCO, NCS, N₃) isolated as red-violet, diamagnetic (ⁿBu₄N) complex salt. The UV-Vis spectra are dominated by the typical π-π* transitions of the Pc^2? ligand at approximately 15100 (B), 28300 (Q₁) und 33500 cm^?1 (Q₂), only fairly dependent of the axial ligands. v(C? O) is observed at 1927 (X = I), 1930 (Cl, Br), 1936 (N₃, NCO) 1948 cm^?1 (NCS), v(C? N) at 2208 cm^?1 (NCO), 2093 cm^?1 (NCS) and v(N? N) at 2030 cm^?1 only in the MIR spectrum. v(Ru? C) coincides in the FIR spectrum with a deformation vibration of the Pc ligand, but is detected in the resonance Raman(RR) spectrum at 516 (X = Cl), 512 (Br), 510 (N₃), 504 (I), 499 (NCO), 498 cm^?1 (NCS). v(Ru? X) is observed in the FIR spectrum at 257 (X = Cl), 191 (Br), 166 (I), 349 (N₃), 336 (NCO) and 224 cm^?1 (NCS). Only v(Ru? I) is RR-enhanced.     

Gold(I) complexes of thioamides

Summary Gold(I) forms linear [AuL₂]X complexes (X = Cl, Br, I or CIO₄) with thioacetamide and thiobenzamide, AuLX compounds with thiobenzamide (X = CI or Br),N, N-dimethylthioformamide (X = Cl, Br or 1) andN-dimethylthioacetamide (X = CI, Br or 1). Thev(AuS) vibrations are assigned in the 320-260 cm^–1 range. The i.r. spectra further suggest hydrogen bonding between the ligands and the anions. The conductivity measurements indicate dissociation of the [AuL₂]X complexes (X = halide) and coordination of X in solution.Presented in part at the XIX ICCC, Prague, 1978.     

Binary and ternary oxorhenium(V) complexes: synthesis,characterization, and crystal structure

A series of anionic five-coordinate binary oxorhenium(V) complexes with dithiolato ligands, Bu₄N[ReO(L¹)₂] (1a), Bu₄N[ReO(L²)₂] (1b), and Bu₄N[ReO(L³)₂] (1c), and a series of neutral octahedral ternary oxorhenium(V) complexes of mixed dithiolato and bipyridine ligands, [ReO(L¹)(bpy)Cl] (2a), [ReO(L²)(bpy)Cl] (2b), and [ReO(L³)(bpy)Cl] (2c) (where L¹H₂ = ethane-1,2-dithiol, L²H₂ = propane-1,3-dithiol, L³H₂ = toluene-3,4-dithiol, and bpy = 2,2′-bipyridine), were isolated and characterized by physicochemical and spectroscopic methods. The solid state structure of 1c was established by X-ray crystallography. All the mononuclear oxorhenium(V) complexes are diamagnetic. The redox behavior of all the complexes has been studied voltammetrically.     

Darstellung,Kristallstrukturen, Schwingungsspektren und Normalkoordinatenanalysen von trans-(PNP)[TcCl4(Py)2] und trans-(PNP)[TcBr4(Py)2]

Preparation, Crystal Structures, Vibrational Spectra, and Normal Coordinate Analysis of trans-(PNP)[TcCl₄(Py)₂] and trans-(PNP)[TcBr₄(Py)₂] By reaction of (PNP)₂[TcX₆] with pyridine in the presence of [BH₄]^? (PNP)[TcX₄(Py)₂], X = Cl, Br, are formed. X-ray structure determinations on single crystals of these isotypic Tc^III complexes (monoclinic, space group P2₁/n, Z = 2, for X = Cl: a = 13.676(4), b = 9.102(3), c = 17.144(2) Å, β = 91.159(1)°; for X = Br: a = 13.972(2), b = 9.146(3), c = 17.285(4) Å, β = 90.789(2)°) result in the averaged bond distances Tc? Cl: 2.386, Tc? Br: 2.519, Tc? N: 2.132(3) (X = Cl) and 2.143(4) Å (X = Br). The two pyridine rings are coplanar and vertical to the X? Tc? X-axes, forming angles of 42.28° (X = Cl) and 43.11° (X = Br). Using the molecular parameters of the X-ray structure determination and assuming D_2h point symmetry, the IR and Raman spectra are assigned by normal coordinate analysis based on a modified valence force field. Good agreement between observed and calculated frequencies is obtained with the valence force constants f_d(TcCl) = 1.45, f_d(TcBr) = 1.035, f_d(TcN) = 1.37 (X = Cl) and 1.45 mdyn/ Å (X = Br), respectively.     

Coordination Polyhedra OsXn(X = F, Cl, Br, I) in Crystal Structures

The Voronoi–Dirichlet polyhedra (VDP) and the method of intersecting spheres were used to perform crystal-chemical analysis of compounds containing complexes [Os _a X _b ] ^z–(X = F, Cl, Br, I). Atoms of Os(V) at X = F and Cl, of Os(IV) at X = Cl, Br, and of Os(III) at X = Br were found to exhibit a coordination number of 6 with respect to the halogen atoms and to form OsX₆octahedra. The coordination polyhedra of Os(III) for X = Cl, I are square pyramids OsX₄. Each Os(III) atom forms one Os–Os bond; as a consequence, the OsBr₆octahedra share a face in forming Os₂Br^3– ₉complexes, while the OsX₄pyramids (X = Cl, I) dimerize to produce [X₄Os–OsX₄]^2–ions. The influence of the valence state of the Os atoms and of the nature of the halogen atoms on the composition and structure of the complexes formed and some characteristics of the coordination sphere of Os were considered.     

Die Kristallstruktur von Tetraphenylarsonium-tetrabromooxotechnetat(V), (Ph4As)TcOBr4

The Crystal Structure of Tetraphenylarsonium-tetrabromooxotechnetate(V), (Ph₄As)TcOBr₄ (Ph₄As)TcOBr₄ has been prepared from (Bu₄N)TcO₄, HBr and (Ph₄As)Br. The crystal structure of the complex has been determined by X-ray diffraction using MoKα radiation. The crystals are tetragonal, space group P 4/n with a = 1276.6(1) pm, c = 803.2(1) pm, Z = 2. The refinement based on 1595 reflexes converged to R = 0.034. The structure consists of discrete TcOBr₄^? anions and Ph₄As⁺ cations. The technetium is coordinated in a square pyramidal environment. A C_4v symmetry was derived for the complex anion. With this, it is isomorphous to the other structurally studied (Ph₄As)TcYX₄ complexes (Y = O, N; X = Cl, Br). The Tc = O length is 161.3(9) pm with Tc? Br 246.0(1) pm     

Darstellung,Kristallstrukturen, Schwingungsspektren und Normalkoordinatenanalysen der Tetrahalogeno‐bis‐Pyridin‐Osmium(III)‐Komplexe cis‐(n‐Bu4N)[OsCl4Py2] und trans‐(n‐Bu4N)[OsX4Py2], X = Cl,Br

Synthesis, Crystal Structures, Vibrational Spectra, and Normal Coordinate Analyses of the Tetrahalogeno‐bis‐Pyridine‐Osmium(III) Complexes cis ‐( n ‐Bu₄N)[OsCl₄Py₂] and trans ‐( n ‐Bu₄N)[OsX₄Py₂], X = Cl, Br By reaction of (n‐Bu₄N)₂[OsX₆], X = Cl, Br, with pyridine and (n‐Bu₄N)[BH₄] tetrahalogeno‐bis‐pyridine‐osmium(III) complexes are formed and purified by chromatography. X‐ray structure determinations on single crystals have been performed of cis‐(n‐Bu₄N)[OsCl₄Py₂] ( 1 ) (triclinic, space group P1, a = 9.4047(9), b = 10.8424(18), c = 17.007(2) Å, α = 71.833(2), β = 81.249(10), γ = 67.209(12)°, Z = 2), trans‐(n‐Bu₄N)[OsCl₄Py₂] ( 2 ) (orthorhombic, space group P2₁2₁2₁, a = 8.7709(12), b = 20.551(4), c = 17.174(4) Å, Z = 4) and trans‐(n‐Bu₄N)[OsBr₄Py₂] ( 3 ) (triclinic, space group P1, a = 9.132(3), b = 12.053(3), c = 15.398(2) Å, α = 95.551(18), β = 94.12(2), γ = 106.529(19)°, Z = 2). Based on the molecular parameters of the X‐ray structure determinations and assuming C₂ point symmetry for the anion of 1 and D_2h point symmetry for the anions of 2 and 3 the IR and Raman spectra are assigned by normal coordinate analysis. The valence force constants of 1 are in the Cl–Os–Cl axis f_d(OsCl) = 1.58, in the asymmetrically coordinated N′–Os–Cl ^· axes f_d(OsCl ^· ) = 1.45, f_d(OsN′) = 2.48, of 2 f_d(OsCl) = 1.62, f_d(OsN) = 2.42 and of 3 f_d(OsBr) = 1.39 and f_d(OsN) = 2.34 mdyn/Å.     

Osmium(II)-Phthalocyanine: Darstellung und Eigenschaften von Di(acido)phthalocyaninatoosmaten(II)

Osmium(II) Phthalocyanines: Preparation and Properties of Di(acido)phthalocyaninatoosmates(II) “H[Os(X)₂Pc^2?]” (X = Br, Cl) reacts in basic medium or in the melt with (ⁿBu₄N)X forming less stable, diamagnetic, darkgreen (ⁿBu₄N)₂[Os(X)₂Pc^2?]. Similar dicyano and diimidazolido(Im) complexes are formed by the reaction of “H[Os(Cl)₂Pc^2?]” with excess ligand in the presence of [BH₄]^?. The cyclic voltammograms show up to three quasireversible redoxprocesses: E_1/2(I) = 0.13 V (X = CN), ?0.03 V (Im), ?0.13 V (Br) resp. ?0.18 V (Cl) is metal directed (Os^II/III), E_1/2(II) = 0.69 V (Cl), 0.71 V (Br), 0.83 V (CN), 1.02 V (Im) is ligand directed (Pc^2?/?) and E_1/2(III) = 1.17 V (Cl) resp. 1.23 V (Br) is again metal directed (Os^III/IV). Between the typical “B” (～16.2 kK) and “Q” (～29.4 kK), “N regions” (～34.1 kK) up to seven strong “extra bands” of the phthalocyanine dianion (Pc^2?) are observed in the uv-vis spectrum. Within the row CN > Im > Br > Cl, most of the bands are shifted slightly, the “extra bands” considerably more to lower energy in correlation with E_1/2(I). The vibrational spectra are typical for the Pc^2? ligand with D_4h symmetry. M.i.r. bands at 514, 909, 1 173 and 1 331 cm^?1 are specific for hexa-coordinated low spin Os^II phthalocyanines. In the resonance Raman (r.r.) spectra polarized, depolarized or anomalously polarized deformation and stretching vibrations of the Pc^2? ligand will be selectively enhanced, if the excitation frequency coincides with “extra bands”. With excitation at ～19.5 kK the intensity of the symmetrical Os? X stretching vibration at 295 cm^?1 (X = Cl), 252 cm^?1 (X = Im) and 181 cm^?1 (X = Br) is r.r. enhanced, too. The asymmetrical Os? X stretching vibration is observed in the f.i.r. spectrum at 345 cm^?1 (X = CN), 274 cm^?1 (X = Cl), 261 cm^?1 (X = Im) and 200 cm^?1 (X = Br).     

trans‐[TcNCl2(Ph3PNH)2] — Synthesis and Structure

The neutral technetium(V) phosphoraneimine complex [TcNCl₂(Ph₂PNH)₂] is formed when (Bu₄N)[TcOCl₄] reacts with Me₃SiNPPh₃ in dichloromethane. Distances of 2.078(4) and 2.102(4) Å have been found between Tc and the neutral triphenylphosphoraneimine ligands. The Tc‐N‐P angles are 133.7(3) and 134.8(3)°. The terminal nitrido ligand is formed by decomposition of an additional molecule of Me₃SiNPPh₃. The protons which are used for the protonation of the organic ligands are released during the decomposition of CH₂Cl₂. The same reaction yields the [TcNCl₄]^— anion when it is performed in acetonitrile.     

Technetium Complexes with 2‐Mercapto‐methyltetrazolate

2‐Mercapto‐methyltetrazolate, Smetetraz^–, acts as monoanionic, monodentate ligand in a number of technetium compounds. Anionic Tc^V complexes of the types [TcO(Smetetraz)₄]^– and [TcN(Smetetraz)₄]^2– are formed when (Bu₄N)[Tc^VOCl₄] or (Bu₄N)[Tc^VINCl₄], respectively, react with Na(Smetetraz). Reduction of the metal takes place in the latter case. (Bu₄N)₂[TcN(Smetetraz)₄] crystallises in the monoclinic space group Pc (a = 9.701(5), b = 17.570(5), c = 16.821(10) Å, β = 96.50(3)°, Z = 2). The Tc atom is situated 0.580(3) Å above the basal plane of a square pyramid which is formed by the sulfur atoms and the nitrido ligand as its apex. The Tc–S bond lengths lie between 2.384(3) and 2.410(3) Å. [Tc(PPh₃)(Smetetraz)₃(CH₃CN)] is formed during the reaction of [TcCl₃(PPh₃)₂(CH₃CN)] with NaSmetetraz as blue needles with co‐crystallised solvent toluene (space group C2/c, a = 24.188(4), b = 14.373(1), c = 25.617(5) Å, β = 109.48(1)°, Z = 8). The metal atom is coordinated by PPh₃ and CH₃CN in the axial position of a trigonal bipyramid. All three aryl rings are on the sterically less strained side of the plane defined by the sulfur atoms. The Tc–S bond lengths range between 2.233(2) and 2.247(2) Å.     

Manganese-Mediated Formic Acid Dehydrogenation

A robust and rapid manganese formic acid (FA) dehydrogenation catalyst is reported. The manganese is supported by the recently developed, hybrid backbone chelate ligand ^tBuPNNOP (^tBuPNNOP=2,6-(di-tert-butylphosphinito)(di-tert-butylphosphinamine)pyridine) ( 1 ) and the catalyst is readily prepared with MnBrCO₅ to form [(^tBuPNNOP)Mn(CO)₂][Br] ( 2 ). Dehydrohalogenation of 2 generated the neutral five coordinate complex (^tBuPNNOP)Mn(CO)₂ ( 3 ). Dehydrogenation of FA by 2 and 3 was found to be highly efficient, exhibiting turnover frequencies (TOFs) exceeding 8500 h⁻¹, rivaling many noble metal systems. The parent chelate, ^tBuPONOP (^tBuPONOP=2,6-bis(di-tert-butylphosphinito)pyridine) or ^tBuPNNNP (^tBuPNNNP=2,6-bis (di-tert-butylphosphinamine)pyridine), coordination complexes of Mn were synthesized, respectively affording [(^tBuPONOP)Mn(CO)₂][Br] ( 4 ) and [(^tBuPNNNP)Mn(CO)₂][Br] ( 5 ). FA dehydrogenation with the hybrid-ligand supported 2 exhibits superior catalysis to 4 and 5 .     

Darstellung,Kristallstrukturen, Schwingungsspektren und Normalkoordinatenanalyse von (n‐Bu4N)2[PtX4(ox)], X = Cl,BR

Synthesis, Crystal Structure, Vibrational Spectra, and Normal Coordinate Analysis of (n‐Bu₄N)₂[PtX₄(ox)], X = Cl, Br By oxidation of (n‐Bu₄N)₂[PtX₂(ox)], X = Cl, Br, with Cl₂ or Br₂ in dichloromethane (n‐Bu₄N)₂[PtCl₄(ox)] ( 1 ) and (n‐Bu₄N)₂[PtBr₄(ox)] ( 2 ) are formed. The crystal structure of [(C₅H₅N)₂CH₂][PtCl₄(ox)] (monoclinic, space group C2/m, a = 15.562(1), b = 13.779(1), c = 10.168(1)Å, ß = 128.099(9)°, Z = 4) reveals complex anions with nearly C_2v point symmetry. The bond lengths in the Cl′‐Pt‐O^˙ axes are Pt‐Cl′ = 2.287 and Pt‐O^˙ = 2.048 and in the Cl‐Pt‐Cl axis Pt‐Cl = 2.314Å. The oxalato ligand is nearly plane with an O‐C‐C‐O torsion angle of 0.5°. In the vibrational spectra the PtX stretching vibrations are observed at 328 and 353 ( 1 ) and 201 and 212 cm^—1 ( 2 ). The PtX′ modes appear at 360 and 343 ( 1 ) and 227 and 238 cm^—1 ( 2 ). The PtO^˙ stretching vibrations are coupled with internal modes of the oxalato ligands and appear in the range of 400—800 cm^—1. Based on the molecular parameters of the X‐ray determination ( 1 ) and estimated data ( 2 ) the IR and Raman spectra are assigned by normal coordinate analysis. The valence force constants are f_d(PtCl) = 2.08, f_d(PtCl′) = 2.29, f_d(PtBr) = 1.56, f_d(PtBr′) = 2.02 and f_d(PtO^˙) = 2.46 ( 1 ) and 2.35 mdyn/Å ( 2 ). Taking into account increments of the trans influence a good agreement between observed and calculated frequencies is achieved. The NMR shifts are δ(¹⁹⁵Pt) = 5623.0 ( 1 ) and 4536.1 ( 2 ).