Oxidative Addition Of Halogens Research Articles

Sterically Constrained Bicyclic Phosphines: A Class of Fascinating Compounds Suitable for Application in Small Molecule Activation and Coordination Chemistry.

Bicyclic phosphines with two annulated, electronically unsaturated five-membered heterocycles are available through facile routes. In most cases, their phosphorus atoms are bound to heteroatoms such as oxygen or nitrogen (PN3 or PN2 O), whereas homoleptic coordination by three sp2 -hybridized carbon atoms has been reported only recently. Steric strain causes unique reactivity. Oxidative addition of halogens, N-H or O-H bonds have afforded phosphoranes as valuable materials for secondary processes. Ring opening was identified as an important step for the understanding of these reactions and has been observed experimentally with a diphosphorus-based ring system. A PH2 derivative has been considered as a model system for small molecule activation, and hydrogen transfer to a diazo compound was observed experimentally. Several of these phosphines are excellent ligands for the coordination of transition-metal atoms. The very bulky PC3 compound has a basicity similar to that of PPh3 and may allow the synthesis of complexes with unusually low coordination numbers at the metal atoms. These phosphines found recently renewed interest as promising reagents in various secondary transformations such as the activation of σ-bonds or in coordination chemistry.

Oxidative addition of halogen across an Os-Os or Os-Sb bond: Formation of five-membered osmium-antimony carbonyl rings

Halogenation of the cluster Os3(CO)10(μ-SbPh2)2, 2, with PhICl2 or I2 affords the five-membered metallacyclic rings Os3(Cl)2(CO)10(μ-SbPh2)2, 3d and Os3(I)2(CO)10(μ-SbPh2)2, 3d-I, respectively, via oxidative addition across an OsOs bond. The reaction of 2 with SbPh2Cl or SbPh2H gives the 3,5-fused rings Os3(X)(CO)9(μ-SbPh2)3, (X = Cl, 4a; H, 4b), respectively. Halogenation of 4 with PhICl2 gives the five-membered metallacyclic rings Os3(Cl)(X)(CO)9(SbPh2Cl)(μ-SbPh2)2 (X = Cl, 5a; H, 5b) via oxidative addition across an OsSb bond. The analogous reaction with I2 also results in oxidative addition across an OsSb bond, but this is followed by displacement of SbPh2I to afford a five-membered metallacycle containing a μ-I ligand, viz., Os3(μ-I)(X)(CO)9(μ-SbPh2)2 (X = Cl, 7a, H, 7b).

ChemInform Abstract: Gold Trifluoromethyl Complexes

AbstractReview: synthesis, reactivity and applications of gold trifluoromethyl complexes; 128 efs.

Oxidative Addition of Halogens on Open Metal Sites in a Microporous Spin‐Crossover Coordination Polymer

Mixing with the guests: Exposure of the porous spin-crossover framework {Fe(pz)[PtII(CN)4]} to X2 (pz=pyrazine; X2=Cl2, Br2, and I2) leads to incorporation of the halides in the coordinatively unsaturated [PtII(CN)4]2− moieties through oxidative addition, thus affording the mixed-valence series {Fe(pz)[PtII/IV(CN)4(X)]}, which features quite distinct cooperative spin-transition properties.

Oxidative Addition of Halogens on Open Metal Sites in a Microporous Spin‐Crossover Coordination Polymer

Innige Verbindung: Die Einwirkung von X2 (Cl2, Br2, I2) auf das poröse Spin-Crossover-Material {Fe(pz)[PtII(CN)4]} (pz=Pyrazin) führt durch oxidative Addition zum Halogenid-Einbau in die koordinativ ungesättigten [PtII(CN)4]2−-Einheiten. Eine Serie gemischtvalenter {Fe(pz)[PtII/IV(CN)4(X)]}-Gerüste mit charakteristischem kooperativem Spinübergang wurde erhalten.

Reactivity of diacetylplatinum(II) complexes: Oxidative addition of halogens and hydrogen halides

Diacetylplatinum(II) complexes [Pt(COMe) 2( ▪)] ( ▪ = bpy, 3a; 4,4′- t-Bu 2-bpy, 3b), obtained by the reaction of [Pt(COMe) 2X(H)( ▪)] with NaOH in CH 2Cl 2/H 2O, were found to undergo oxidative addition reactions with halogens (Br 2, I 2) yielding the platinum(IV) complexes ( trans, OC-6-13)/( cis, OC-6-32) [Pt(COMe) 2X 2( ▪)] ( ▪ = bpy, X = Br, 4a/4b; I, 4c/ 4d; ▪ = 4,4′- t-Bu 2-bpy, X = Br, 4e/4f; I, 4g/ 4h). The diastereoselectivity of the reactions proved to be strongly dependent on the solvent. The oxidative addition of (SCN) 2 resulted in the formation of ( OC-6-13)-[Pt(COMe) 2(SCN) 2( ▪)] ( ▪ = bpy, 4i; 4,4′- t-Bu 2-bpy, 4j). In a reaction the reverse of their formation, the diacetylplatinum(II) complexes 3 underwent oxidative addition with anhydrous HX (X = Cl, Br, I), prepared in situ from Me 3SiX/H 2O, yielding diacetyl(hydrido)platinum(IV) complexes [Pt(COMe) 2X(H)( ▪)] ( ▪ = bpy, X = Cl, 5a; Br, 5b; I, 5c; ▪ = 4,4′- t-Bu 2-bpy, X = Cl, 5d; Br, 5e; I, 5f). Furthermore, diacetyldihaloplatinum complexes 4 were found to undergo reductive elimination reactions in boiling methanol yielding acetylplatinum(II) complexes [Pt(COMe)X( ▪)] ( ▪ = bpy, X = Br, 6b; I, 6c; ▪ = 4,4′- t-Bu 2-bpy, X = Br, 6e; I, 6f). All complexes were characterized by microanalysis, IR and 1H and 13C NMR spectroscopy. Additionally, the bis(thiocyanato) complex 4j was characterized by single-crystal X-ray diffraction analysis.

Group IV Imino-Semiquinone Complexes Obtained by Oxidative Addition of Halogens

An isostructural series of titanium, zirconium, and hafnium complexes, M[ap] 2L 2 (M = Ti, Zr, Hf; L = THF, pyridine), of the redox-active 4,6-di- tert-butyl-2- tert-butylamidophenolate ligand ([ap] (2-)) have been prepared. The zirconium and hafnium derivatives react readily with halogen oxidants such as XeF 2, PhICl 2, and Br 2, leading to products in which one-electron oxidation of each [ap] (2-) ligand accompanies halide addition to the metal center. Iodine proved to be too weak of an oxidant to yield the corresponding oxidative addition product, and under no conditions could halogen oxidative addition products be obtained for titanium. According to X-ray crystallographic studies, the zirconium and hafnium oxidation products are best formulated as MX 2[isq.] 2 ([isq.] (-) = 4,6-di- tert-butyl-2- tert-butylimino-semiquinonate; M = Zr, Hf; X = F, Cl, Br) species, in which the molecule is symmetric with each redox-active ligand in the semiquinone oxidation state. Temperature-dependent magnetization measurements suggest a singlet ( S = 0) ground-state for the diradical complexes with a thermally accessible triplet ( S = 1) excited state. Solution electron paramagnetic resonance (EPR) spectra are consistent with this assignment, showing both Delta m s = 1 and Delta m s = 2 transitions for the antiferromagnetically coupled electrons.

Functionalized Organotellurium Halides: Synthesis, Characterization, and Observation of Intra- and Intermolecular Secondary Bonding

Activated tellurium, but not selenium, reacts with para-substituted benzoylmethyl bromides as well as with iodoacetamide at their melting points in absence of a solvent to give bis(p-substituted benzoylmethyl)tellurium dibromides, (p-YC6H4COCH2)2TeBr2, (Y = H, Me, and MeO) and bis(acetamido)tellurium diiodide, (H2NCOCH2)2TeI2, respectively. Quick reduction of (p-YC6H4COCH2)2TeBr2, with sodium metabisulphite in a two-phase system yields crystalline (p-YC6H4COCH2)2Te. These tellurides undergo smooth oxidative addition of halogens, interhalogen ICl or a pseudohalogen (SCN)2. Intramolecular coordination of the carbonyl group in these functionalized diorganotellurium dihalides is evident from IR spectra and shorter Te···O (carbonyl) distances in comparison to the sum of van der Waals radii and completes six coordination around Te atom. Not unexpectedly, therefore, intermolecular secondary bonding effects of the type Te…O, Te···X and X···X are missing in (PhCOCH2)2TeBr2, (p-MeOC6H4COCH2)TeBr2 and (PhCOCH2)2TeI2. Instead, these compounds provide rare examples, among organotellurium compounds, of supramolecular architecture, where C–H···Br and C–H···O hydrogen bonds and π-π (phenyl ring) interactions appear to be the noncovalent intermolecular associative forces that dominate the crystal packing.

Cyclic voltammetry of heterocyclic Au(I) and Au(III) carbene complexes

Imidazolinylidene and thiazolinylidene complexes of gold in acetonitrile have been investigated by cyclic voltammetry. No Au(II) intermediate was observed during the redox reactions and Au(III) compounds form only by oxidative addition of halogens.

New C,P-Cyclometalated Compounds of Platinum(II) and Platinum(IV) Derived from Tri-o-tolylphosphine

The reaction between [trans-PtCl2(PhCN)2] (PhCN = benzonitrile) and tri-o-tolylphosphine rendered [Pt{CH2C6H4P(o-tolyl)2-C,P}(μ-Cl)]2 (1), a new C,P-cyclometalated compound of Pt(II). The treatment of 1 with AgClO4 (1: 2) in NCMe gave the mononuclear compound [Pt{CH2C6H4P(o-tolyl)2-C,P}(NCMe)2]ClO4 (2). Solutions probably containing the cation [Pt{CH2C6H4P(o-tolyl)2-C,P}(THF)2]+ (THF = tetrahydrofuran) reacted with sodium dimethyldithiocarbamate (NaS2CNMe2) and potassium ethyl xanthate (KS2COEt) in 1:1 molar ratio yielding the mononuclear complexes [Pt{CH2C6H4P(o-tolyl)2-C,P}(S2CR)] (R: NMe2 (3), OEt (4)). The molecular structure of 3 was determined by X-ray diffraction. The reactions of 3 and 4 with Cl2, Br2 and I2 gave the mononuclear Pt(IV) complexes [Pt{CH2C6H4P(o-tolyl)2-C,P}(S2CR)X2] (X: Cl, Br, I) (5−10). In each reaction a single product can be detected spectroscopically, indicating that the oxidative addition of halogens (X2) to 3 and 4 proceeds stereoselectively. The molecular structure of co...

Synthesis and electrochemistry of heterobridged gold(I) and gold(II) complexes of pyridine-2-thiolate. Crystal structures of [Au2{µ-(CH2)2PPh2}(µ-C5H4NS)] and [Au2{µ-(CH2)2PPh2}(µ-C5H4NS)Br2

The reaction of [Au2{µ-(CH2)2PPh2}2] or [Au2(µ-L–L)2][ClO4]2[L–L = dppm (Ph2PCH2PPh2) or dppe (Ph2PCH2CH2PPh2)] with [Aun(µ-C5H4NS)n] led to the heterobridged dinuclear complexes [Au2{µ-(CH2)2PPh2}(µ-C5H4NS)] or [Au2(µ-C5H4NS)(µ-L–L)]ClO4. The structure of [Au2{µ-(CH2)2PPh2}(µ-C5H4NS)] has been established by X-ray crystallography and exhibits a short intermolecular gold–gold distance of 2.8623(7)Å, whereas the shortest intermolecular distance is 3.984 Å. The complex crystallized in the monoclinic space group P21/n with a= 9.430(2), b= 8.819(2), c= 22.786(5)Å, β= 99.08(3)°, Z= 4. Cyclic voltammograms showed that this complex is irreversibly oxidised at a platinum electrode; chemical oxidation with the ferrocenium ion in the presence of halide or pseudohalide ions gave the gold(II) complexes [Au2{µ-(CH2)2PPh2}(µ-C5H4NS)X2](X = Cl, Br, I or SCN). The same derivatives can be obtained by oxidative addition of halogen and/or by subsequent substitution with other halogens or pseudohalogens. The complex [Au2{µ-(CH2)2PPh2}(µ-C5H4NS)Br2] crystallized in the triclinic space group P with a= 14.810(10), b= 14.908(10), c= 17.041(12)Å, α= 70.20(5), β= 69.77(5), γ= 89.19(5)°, Z= 6 (at –100 °C). The Au–Au bond lengths in the three independent molecules are 2.564(4), 2.548(4) and 2.547(4)Å.

ChemInform Abstract: Synthesis of o‐Nitrophenylplatinum(IV) Complexes; Crystal and Molecular Structure of Dichlorobis(2‐nitrophenyl‐C′O)platinum(IV).

AbstractThe oxidative addition of halogens or MeI to the Pt(II) complex (I) leads to the Pt(IV) trans‐complexes (II) and the cis‐complex (III).

Novel anionic gold(I) and gold(III) organocomplexes

Summary Tetrahydrothiophen (tht) and/or chloride may readily be displaced from ClAu(tht) with perhaloaryl lithium to give anionic complexes of the [R 2 Au] − or [RAuX] − type (R = C 6 F 5 or C 6 Cl 5 ; X = Cl or Br). Anionic gold(III) complexes can be prepared both by the reaction of Cl 3 Au-(tht) or K[AuCl 4 ] with LiC 6 F 5 or by the oxidative addition of halogens or (C 6 F 5 ) 2 TlBr to gold(I) complexes.

Oxidative addition of halogens and pseudohalogens to dihalo(1,10-phenanthroline)platinum(II)

Oxidative addition of halogens and pseudohalogens to dihalo(1,10-phenanthroline)platinum(II)