Magnetostructural examination of Mn(III) complexes [Mn(cyclam)X2]+ with strong axial ligands

Three novel Mn(III) cyclam complexes, [Mn(cyclam)(NCBH₃)₂](CF₃SO₃), [Mn(cyclam)(NCBPh₃)₂](CF₃SO₃), and [Mn(cyclam)(NCSe)₂](CF₃SO₃) · H₂O, have been synthesized. These complexes are in the high-spin state between 4 and 350 K, and show large zero-field splittings. The crystal structure of [Mn(cyclam)(NCBH₃)₂](CF₃SO₃) was determined where the axial elongation of Mn–N bonds is found to be the largest among the homologue complexes. Ligand field in the [Mn(cyclam)X₂]⁺ complex series was examined by angular-overlap model calculation.     

Kinetics and mechanism of reaction of trans-(diaqua)(N,N′-ethylene-bis-salicylidenimine) chromium(iii) with sulfur(iv): The labilizing effect of coordinated sulfite

The reaction of trans-[Cr(Salen)(OH₂)₂]⁺ with aqueous sulfite yields trans-[Cr(Salen)(OH₂)(OSO₂(SINGLEBOND)O)]⁻ (O-bonded isomer). The rate and activation parameter data for the formation of the sulfito complex are consistent with a mechanism involving rate-limiting addition of SO₂ to the Cr^III(SINGLEBOND)OH bond. The complex ions, trans-[(OH₂)Cr(Salen)(OSO₂(SINGLEBOND)O)]⁻, and trans-[(OH)Cr(Salen)(OSO₂(SINGLEBOND)O)]²⁻, undergo reversible anation by NCS⁻, N₃⁻, imidazole, and pyridine resulting in the formation of trans-[XCr(Salen)(OSO₂(SINGLEBOND)O)]^(N+1)−(n=1 for X=N₃⁻,NCS⁻, and 0 for X=imidazole and pyridine) predominantly via dissociative interchange mechanism. The labilizing action of the coordinated sulfite on the trans-Cr^III-X bond in trans-[XCr(Salen)(OSO₂)]⁽ⁿ⁺¹⁾⁻ follows the sequence: NCS⁻pyridine ca. N₃⁻ ca. imidazole. Data analysis indicated that the coordinated sulfite has little trans activating influence. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 373–384, 1998     

Adducts of coordination compounds-XIII. Nitrates,hydrogen and silver dinitrates,and polysilver nitrates of trans-dihalotetrakispyridinerhodium(III) and iridium(III) ions

The synthesis and characterization, chiefly as salts of the anions [X(ONO₂)₂]⁻ (X = H⁺ or Ag⁺) (by analysis, X-ray powder photography, vibrational spectra and thermogravimetry) of adducts of the nitrates trans-[M(L)₄X₂](NO₃) (M =Rh or Ir; L = pyridine, perdeuteriopyridine or 4-methylpyridine; X = Cl or Br) with hydrogen nitrate and silver nitrate are described.     

Trifluoromethyl and mixed hydrido trifluoromethyl complexes of iridium(III) as potential precursors of an iridium(I) trifluoromethyl complex

Abstraction of iodide from Ir(CF₃)ClI(CO)(PPh₃)₂ (1) by AgSbF₆ in the presence of acetonitrile yields the cationic complex [Ir(CF₃)Cl(MeCN)(CO)(PPh₃)₂]⁺ [SbF₆]⁻ (2). The acetonitrile group of 2 is readily displaced, and 2 reacts with para-tolyl isocyanide to yield [Ir(CF₃)Cl(CN-p-tolyl)(CO)(PPh₃)₂]⁺ [SbF₆]⁻ (3). The addition of NaOMe to 3 results in the methoxyester complex Ir(CF₃)(COOMe)Cl(CN-p-tolyl) (PPh₃)₂ (4). The acetonitrile ligand of 2 is also displaced by anions, including H⁻. Thus, 2 reacts with LiEt₃BH to give Ir(CF₃)HCl(CO)(PPh₃)₂ (5), in which the hydrido and trifluoromethyl ligands are mutually trans. In contrast, the addition of excess NaBH₄ to 2 affords the novel dihydrido complex trans-Ir(CF3)H₂(CO)(PPh₃)₂ (6). Investigations into the potential use of 5 and 6 as precursors of an iridium(I) complex such as Ir(CF₃)(CO)(PPh₃)₂ are also described.     

Chirale Halbsandwich‐Pentamethylcyclopentadienyl‐Rhodium(III)‐ und Iridium(III)‐Komplexe mit Schiff‐Basen aus Salicylaldehyd und α‐Aminosäureestern [1]

Chiral Half‐sandwich Pentamethylcyclopentadienyl Rhodium(III) and Iridium(III) Complexes with Schiff Bases from Salicylaldehyde and α‐Amino Acid Esters [1] A series of diastereoisomeric half‐sandwich complexes with Schiff bases from salicylaldehyde and L‐α‐amino acid esters including chiral metal atoms, [(η⁵‐C₅H₅)(Cl)M(N,O‐Schiff base)], has been obtained from chloro bridged complexes [(η⁵‐C₅Me₅)(Cl)M(μ‐Cl)]₂ (M = Rh, Ir). Abstraction of chloride from these complexes with Ag[BF₄] or Ag[SO₃CF₃] affords the highly sensitive compounds [(η⁵‐C₅Me₅)M(N,O‐Schiff base]⁺X^? (M = Rh, Ir; X = BF₄, CF₃SO₃) to which PPh₃ can be added under formation of [(η⁵‐C₅Me₅)M(PPh₃)(N,O‐Schiff base)]⁺X^?. The diastereoisomeric ratio of the complexes ( 1 ‐ 7 and 11 ‐ 12 ) has been determined from NMR spectra.     

Stability of AgIII towards Halides in Organosilver(III) Complexes

The involvement of silver in two-electron Ag^I/Ag^III processes is currently emerging. However, the range of stability of the required and uncommon Ag^III species is virtually unknown. Here, the stability of Ag^III towards the whole set of halide ligands in the organosilver(III) complex frame [(CF₃)₃AgX]⁻ (X=F, Cl, Br, I, At) is theoretically analyzed. The results obtained depend on a single factor: the nature of X. Even the softest and least electronegative halides (I and At) are found to form reasonably stable Ag^III−X bonds. Our estimates were confirmed by experiment. The whole series of nonradiative halide complexes [PPh₄][(CF₃)₃AgX] (X=F, Cl, Br, I) has been experimentally prepared and all its constituents have been isolated in pure form. The pseudohalides [PPh₄][(CF₃)₃AgCN] and [PPh₄][(CF₃)₃Ag(N₃)] have also been isolated, the latter being the first silver(III) azido complex. Except for the iodo compound, all the crystal and molecular structures have been established by single-crystal X-ray diffraction methods. The decomposition paths of the [(CF₃)₃AgX]⁻ entities at the unimolecular level have been examined in the gas phase by multistage mass spectrometry (MSⁿ). The experimental detection of the two series of mixed complexes [CF₃AgX]⁻ and [FAgX]⁻ arising from the corresponding parent species [(CF₃)₃AgX]⁻ demonstrate that the Ag−X bond is particularly robust. Our experimental observations are rationalized with the aid of theoretical methods. Smooth variation with the electronegativity of X is also observed in the thermolyses of bulk samples. The thermal stability in the solid state gradually decreases from X=F (145 °C, dec.) to X=I (78 °C, dec.) The experimentally established compatibility of Ag^III with the heaviest halides is of particular relevance to silver-mediated or silver-catalyzed processes.     

Syntheses,characterisation and solid state thermal studies of 1-(2-aminoethyl)piperidine (L), 1-(2-aminoethyl)pyrrolidine (L′) and 4-(2-aminoethyl)morpholine (L″) complexes of nickel(II): X-ray single crystal structure analyses of trans-[NiL2(CH3CN)2](ClO4)2, trans-[NiL2(NCS)2] and trans-[NiL″2(NCS)2]

Reactions of nickel(II) salts with substituted ethane-1,2-diamine where one of the amine nitrogens is a part of a flexible cyclic ring, e.g. 1-(2-aminoethyl)piperidine (L), 1-(2-aminoethyl)pyrrolidine (L′) and 4-(2-aminoethyl)morpholine (L″) produce a number of complexes of the type: (i) Ni(AA)₂X₂ (where X=CF₃CO₂ ⁻, SCN⁻ and NO₂ ⁻; AA represents L/L′/L″); (ii) Ni(AA)₂(CH₃CN)₂X₂ (X=ClO₄ ⁻ and NO₃ ⁻); (iii) Ni(AA)₂(H₂O)₂X₂ (X=CF₃SO₃ ⁻, Cl⁻, Br⁻ and I⁻); and (iv) Ni(AA)₂(H₂O)₄X₂ (X=0.5SO₄ ²⁻, 0.5SeO₄ ²⁻ and CF₃SO₃ ⁻). The complexes possess octahedral geometry. The major complexes upon desolvation retain trans-geometry, some of which are cis with respect to the counter-anion and a few of them are square planar. X-ray single crystal structure analyses of trans-[NiL₂(CH₃CN)₂](ClO₄)₂, trans-[NiL₂(NCS)₂] (violet) and trans-[NiL″₂(NCS)₂] (sky-blue) have been done. The violet and sky-blue thiocyanato species have blue and green coloured isomers, respectively, and these pairs of isomers are proposed to be conformational isomers. Solid state thermal investigation of the complexes has been carried out. The complexes show thermochromism due to deaquation–anation/deaquation reaction/change of conformation. Only [NiL₂](ClO₄)₂, [NiL′₂(CF₃CO₂)₂] and [NiL″₂(NO₂)₂] undergo thermally induced phase transition. The effect of flexible ring size on diamine has been discussed.     

Reaktive hydrido-iridium(III)-komplexe mit den schwach koordinierten anionen BF4−, CF3SO3− und C4F9SO3−

Oxidative addition of HBF₄, CF₃SO₃H and C₄F₉SO₃H to trans-(Ph₃P)₂Ir(L)Cl (L = CO, N₂) gives the highly reactive irridium(III) complexes (Ph₃P)₂Ir(L)(Cl)(H)(X) (X = BF₄, CF₃SO₃, C₄F₉SO₃), in which the anion X can be easily substituted by σ- and π-donors. In the dinitrogen complex (Ph₃P)₂Ir(N₂)(Cl)(H)(FBF₃) (2a) both the N₂ and BF₄ ligands are replaced by valinate, diethyldithiocarbamate or tertiary phosphines, respectively. 2a catalyzes the hydrogenation of cyclohexene and the isomerisation of 1,5-cyclooctadiene.     

Catalytic and Stoichiometric Baeyer–Villiger Oxidation Mediated by Nonheme Peroxo-Diiron(III), Acylperoxo,and Iodosylbenzene Iron(III) Intermediates

In this paper we describe a detailed mechanistic studies on the [Fe^II(PBO)₂(CF₃SO₃)₂] (1), [Fe^II(PBT)₂(CF₃SO₃)₂] (2), and [Fe^II(PBI)₃](CF₃SO₃)₂ (3)-catalyzed (PBO = 2-(2′-pyridyl)benzoxazole, PBT = 2-(2′-pyridyl)benzthiazole, PBI = 2-(2′-pyridyl)benzimidazole) Baeyer–Villiger oxidation of cycloketones by dioxygen with cooxidation of aldehydes and peroxycarboxylic acids, including the kinetics on the reactivity of (μ-1,2-peroxo)diiron(III), acylperoxo- and iodosylbenzene-iron(III) species as key intermediates.     

Crystal structure,electrochemical and photochemical studies of the trans-[Fe(cyclam)(NO)Cl]Cl2 complex (cyclam = 1,4,8,11-tetraazacyclotetradecane)

The trans-[Fe(cyclam)(NO)Cl]Cl₂ complex was synthesized by the reaction of cis-[Fe(cyclam)Cl₂]Cl with NO gas. The X-ray structure of the complex showed that the [Fe–NO] moiety is linear, consistent with the NO⁺ character of the nitric oxide ligand. This suggestion was reinforced by the IR data, which showed the νNO at 1888 cm⁻¹. The cyclic voltammogram of the trans-[Fe(cyclam)(NO)Cl]²⁺ complex presented three electrochemical processes at −0.70, 0.08 and 0.40 V versus Ag/AgCl. The first and last redox processes are centered at the NO ligand, whereas the second is characteristic of the generated aqua species, trans-[Fe(cyclam)Cl(H₂O)]²⁺. Upon irradiation at 330 nm, pH 3.4, the title complex releases the NO moiety with the concomitant generation of the trans-[Fe(cyclam)(H₂O)Cl]⁺ complex as suggested by electronic and IR spectroscopy as well as by cyclic voltammetry technique.     

Synthesis and variable coordination modes of a bis-thiophene-appended macrocycle in complex with cobalt(III)

The bis-thiophene appended cyclam derivative L³ (trans-6,13-dimethyl-6,13-bis(thiophene-3′-ylmethylamino)-1,4,8,11-tetraazacyclotetradecane) has been synthesised, characterised and complexed with Co^III. The crystal structure of the diprotonated ligand as its cyanoborohydride salt [H₂L³][NCBH₃]₂ is reported. Variable coordination modes to Co^III have been identified that find the ligand binding either as a tetradentate (cyclam-like) macrocycle in the structurally characterised complexes trans-[CoL³Cl₂]Cl and trans-[CoL³(NCBH₃)(OH)]Cl or as a hexadentate in [CoL³]Cl₃ where both functionalised exocyclic amines coordinate in trans coordination sites. In this case, we have found that the structure of the hexadentate coordinated complex [CoL³]³⁺ is significantly tetragonally elongated due to steric effects of the thiophene rings and this also leads to a very large 500 mV anodic shift in the Co^III/II redox potential relative to the unsubstituted hexaamine complex of Co^III.     

Synthesis and multinuclear NMR investigation on gold(III)-triphenylphosphine-pentafluorophenyl-arylazoimidazole

Reaction of [Au(C₆F₅)(PPh₃)(OSO₂CF₃)₂] with RaaiR′ in dichloromethane medium followed ligand addition leads to [Au(PPh₃)(C₆F₅)(RaaiR′)](OSO₂CF₃)₂ where RaaiR′ = p-R-C₆H₄-N=N-C₃H₂-NN-1-R′ (I–III), abbreviated as N, N′-chelator, where N(imidazole) and N(azo) represent N and N′, respectively; R = H (a), Me (b), Cl (c) and R′ = Me (I), CH₂CH₃ (II), CH₂Ph (III), PPh₃ is triphenylphosphine, OSO₂CF₃ is the triflate anion. The maximum molecular peak of the corresponding molecule is observed in the ESI mass spectrum. IR spectra of the complexes show -C=N- and -N=N- stretching near at ∼1590 and 1370 cm⁻¹ and at ∼1100, 755, 695, 545, and 505 cm⁻¹ due to the presence of triphenylphosphine and pentafluoropheny ring. The ¹H NMR spectral measurements suggest methylene (-CH₂-) in RaaiEt that gives a complex AB type multiplet with coupling constant of av. 6.6 Hz while in RaaiCH₂Ph it shows AB type quartets with coupling constant of av. 6.2 Hz. Considering all the moitie there are a lot of different carbon atoms in the molecule which gives a lot of eleven different peaks in the ¹³C {¹H}NMR spectrum. In the ¹H-¹H COSY NMR spectrum of the present complexes and contour peaks in the ¹H-¹³C HMQC NMR spectrum in the present complexes, assign the solution structure and stereo-retentive transformation in each step. The article is published in the original.     

Structural control in palladium(II)-catalyzed enantioselective allylic alkylation by new chiral phosphine-phosphite and pyridine-phosphite ligands

The ligands 6-[(diphenylphosphanyl)methoxy]-4,8-di-tert-butyl-2,10-dimethoxy-5,7-dioxa-6-phosphadibenzo[a,c]cycloheptene, 1, (S)-4-[(diphenylphosphanyl)methoxy]-3,5-dioxa-4-phosphacyclohepta[2,1-a;3,4a′]dinaphthalene, (S)-2, and (S)-4-[(diphenylphosphanyl)methoxy]-2,6-bis-trimethylsilanyl-3,5-dioxa-4-phosphacyclohepta[2,1-a;3,4-a′]dinaphthalene, (S)-3, (S)-2-(3,5-dioxa-4-phosphacyclohepta[2,1-a;3,4-a′]dinaphthalen-4-yloxymethyl)pyridine, (S)-4, and (S)-2-(3,5-dioxa-4-phosphacyclohepta[2,1-a;3,4-a′]dinaphthalen-4-yloxy)pyridine, (S)-5, have been easily prepared.The cationic complexes [Pd(η³-C₃H₅)(L-L′)]CF₃SO₃ (L–L′=1–(S)-5) and [Pd(η³-PhCHCHCHPh)(L–L′)]CF₃SO₃ (L–L′=(S)-2–(S)-4) were synthesized by conventional methods starting from the complexes [Pd(η³-C₃H₅)Cl]₂ and [Pd(η³-PhCHCHCHPh)Cl]₂, respectively. The behavior in solution of all the π-allyl- and π-phenylallyl-(L–L′)palladium derivatives 6–14 was studied by ¹H, ³¹P{¹H}, ¹³C{¹H} NMR and 2D-NOESY spectroscopy. As concerns the ligands (S)-4 and (S)-5, a satisfactory analysis of the structures in solution was possible only for palladium–allyl complexes [Pd(η³-C₃H₅)((S)-4)]CF₃SO₃, 11, and [Pd(η³-C₃H₅)((S)-5)]CF₃SO₃, 12, since the corresponding species [Pd(η³-PhCHCHCHPh)((S)-4)]CF₃SO₃, 13, and [Pd(η³-PhCHCHCHPh)((S)-5)]CF₃SO₃, 14, revealed low stability in solution for a long time. The new ligands (S)-2–(S)-5 were tested in the palladium-catalyzed enantioselective substitution of (1,3-diphenyl-1,2-propenyl)acetate by dimethylmalonate. The precatalyst [Pd(η³-C₃H₅)((S)-2)]CF₃SO₃ afforded the allyl substituted product in good yield (95%) and acceptable enantioselectivities (71% e.e. in the S form). A similar result was achieved with the precatalyst [Pd(η³-C₃H₅)((S)-3)]CF₃SO₃. The nucleophilic attack of the malonate occurred preferentially at allylic carbon far from the binaphthalene moiety, namely trans to the phosphite group. When the complexes containing ligands (S)-4 and (S)-5 were used as precatalysts, the product was obtained as a racemic mixture in high yield. The number of the configurational isomers of the Pd-allyl intermediates present in solution in the allylic alkylation and the relative concentrations are considered a determining factor for the enantioselectivity of the process.     

Synthesis and reactions of trans-dicarbonyl bis-[1,2-bis(dimethylphosphino)ethane] vanadium(O): X-ray crystal structures of trans-V(CO)2(dmpe)2 [cis-V(CO)2(dmpe)2(CH3CN)]BPh4 and cis-V(CO)2(dmpe)2(O2CEt)

Interaction of trans-VCl₂(dmpe)₂ with sodium amalgam in tetrahydrofuran under CO gives trans-V(CO)₂(dmpe)₂. The latter is oxidized by Ag⁺ in acetonitrile to give [cis-V(CO)₂(dmpe)₂(CH₃CN)]⁺, isolated as the tetraphenylborate. Interactions with acids (HX) gives neutral complexes of the type V(CO)₂(dmpe)₂X (X = Cl, MeCO₂, EtCO₂, CF₃CO₂, PhPO₂H or NH₂SO₃); the chloride can be exchanged with N₃⁻ or CN⁻ in methanol. X-ray structural studies confirm the trans stereochemistry for V(CO)₂(dmpe)₂ and the seven-coordination of V^I in both [V(CO)₂(dmpe)₂(CH₃CN)][BPh₄] and V(CO)₂(dmpe)₂(O₂CEt), which have a pseudo octahedral geometry with the two carbonyls occupying a “split” axial site. ⁵¹V NMR and other spectra are reported.     

Syntheses of (imidazole)pentaamminemetal(III) and μ-imidazolatodecaamminedimetal(III) complexes from trifluoromethanesulfonato precursors

The [M(NH₃)₅(imidH)]³⁺ complex ions (M = Co, Rh or Ir; imidH = imidazole) can be readily prepared by reaction of [M(NH₃)₅(OSO₂CF₃)]²⁺ ions with imidazole in sulfolane. Subsequent reaction of [M′(NH₃)₅(OSO₂CF₃)]²⁺ with [M(NH₃)₅(imidH)]³⁺ in sulfolane in the presence of a non-coordinating base permits synthesis of the binuclear imidazolate-bridged complexes [(NH₃)₅M(imid)M′(NH₃)₅]⁵⁺ (M = M′= Co or Rh; M = Co, M′ = Rh), characterized by spectroscopic, chromatographic and voltammetric methods, and by reactivity.     

Gold(I) and gold(III) ortho-nitrophenyl complexes. Crystal and molecular structure of ortho-nitrophenyltriphenylarsinegold(I)

The reaction between [Au(o-C₆H₄NO₂)Cl]⁻ and tetrahydrothiophene (tht) in the presence of NaClO₄ give a solution (probably containing [Au(o-C₆H₄NO₂)(tht)]) that can be used to prepare neutral [Au(o-C₆H₄NO₂)L_n] (L = AsPh₃, n = 1; L = SbPh₃, n = 2; L = 1,10-phenanthroline, n = 1) or anionic [Au(o-C₆H₄-NO₂(CN)]⁻ complexes. Treatment of [Au(o-C₆H₄NO₂)(PPh₃)] with chlorine or PhICl₂ gives trans- or cis-[Au(o-C₆H₄NO₂)Cl₂(PPh₃)]. Isomerizations occur when the cis-isomer is treated with concentrated solutions of chlorine or when the trans-isomer is heated.An X-ray diffraction study of [Au(o-C₆H₄NO₂)(AsPh₃)] has revealed an almost linear coordination around the gold atom (AsAuC mean value 177(2)°). The AuO distance is too long (mean value 2.80(3) Å) for intramolecular coordination.     

Substitution reactions of trans-[PdXPh(SbPh3)2J (X=Cl or Br) with nitrogen,phosphines and arsenic donor ligands. Crystal structures of trans-[PdClPh(PPh3)2], [PdClPh(bipy)], [PdClPh(dppm)]2, and [PdBrPh(dppm)]2

Exchange reactions of trans-[PdXPh(SbPh₃)₂] (1) (X=Cl or Br) with ligands L in refluxing dichloromethane give the palladium phenyl complexes [PdXPhL₂] (X=Cl, L=PPh₃, AsPh₃, L₂=2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine (dmbipy), 1,10-phenanthroline (phen); X=Br, L=PPh₃, L₂=bipy). Treatment of the complexes with bis(diphenylphosphino)methane (dppm) in refluxing dichloromethane gives [PdXPh(dppm]₂. These complexes have been characterised by microanalysis, IR and ¹H NMR spectroscopic data together with single crystal X-ray determinations of the phenyl palladium complexes, trans-[PdClPh(PPh₃)₂], [PdClPh(bipy)], [PdClPh(dppm)]₂, and [PdBrPh(dppm)]₂.     

Organonitrile complexes of iron(II) and Ruthenium(II): X-ray crystal structure of trans-[Fe(NCMe)2(dmpe)2](BPh4)2

The interaction of FeCl₂(dmpe)₂ [dmpe = 1,2-bis(dimethylphosphino)ethane] with RCN (R = Me or Et) gives the partially substituted complex trans-[FeCl(NCR)(dmpe)₂]Cl at room temperature, but in refluxing RCN in the presence of NaBPh₄ the product is trans-[Fe(NCR)₂(dmpe)₂](BPh₄)₂. The X-ray crystal structure of the acetonitrile complex has been determined. No reaction is observed between RuCl₂(dmpe)₂ and MeCN, although the disubstituted complex can be made in a similar way to the iron analogue. The interaction of trans-[M(NCMe)₂(dmpe)₂][BPh₄)₂ (M = Fe or Ru) with H₂ leads to the amine complexes trans-[M(H₂NEt)₂(dmpe)₂](BPh₄)₂. Although the ethylamine can be removed on refluxing in MeCN the complexes do not act as catalysts. Addition of MeCN to FeCl₂(PMe₃)₂ yields only the complex [FeCl(NCMe)(PMe₃)₂]Cl; RuCl₂(PMe₃)₄ reacts in refluxing MeCN in the presence of NaBPh₄ to give trans-[Ru(NCMe)₂(PMe₃)₄](BPh₄)₂.     

Synthesis and characterization of Ru(III), Rh(III), Pt(IV) and Ir(III) thiosemicarbazone complexes

Ru(III), Rh(III), Pt(IV) and Ir(III) complexes of 2-furfural thiosemicarbazone as ligand have been synthesised. These complexes have the composition [M(ligand)₂X₂]X (M = Ru(III) Rh(III) and Ir(III) X = Cl and Br) and [Pt(ligand)₂ X₂] X₂ (X = Cl, Br and 1/2SO₄). The deprotonated ligand forms the complexes of the formulae M(ligand-H)₃ and Pt(ligand-H)₃Cl. All these complexes have been characterized by elemental analysis, magnetic measurements, electronic and infrared spectral studies. All the complexes are six-coordinate octahedral.     

An Organogold(III) Difluoride with a trans Arrangement

The trans isomer of the organogold(III) difluoride complex [PPh₄][(CF₃)₂AuF₂] has been obtained in a stereoselective way and in excellent yield by reaction of [PPh₄][CF₃AuCF₃] with XeF₂ under mild conditions. The compound is both thermally stable and reactive. Thus, the fluoride ligands are stereospecifically replaced by any heavier halide or by cyanide, the cyanide affording [PPh₄][trans‐(CF₃)₂Au(CN)₂]. The organogold fluoride complexes [CF₃AuF_x]^? (x=1, 2, 3) have been experimentally detected to arise upon collision‐induced dissociation of the [trans‐(CF₃)₂AuF₂]^? anion in the gas phase. Their structures have been calculated by DFT methods. In the isomeric forms identified for the open‐shell species [CF₃AuF₂]^?, the spin density residing on the metal center is found to strongly depend on the precise stereochemistry. Based on crystallographic evidence, it is concluded that Auⁱⁱⁱ and Agⁱⁱⁱ have similar covalent radii, at least in their most common square‐planar geometry.