Syntheses and structures of diorgano(halo- orpseudohalo-)(1,3-dithiole-2-thione-4,5-dithiolato)-stannates (1-), [Q][RSnX(dmit)] (Q=onium cation; X=halide orpseudohalide)

Ionic compounds, [Q] [R₂SnX(dmit)][dmit=1,3-dithiole-2-thione-dithiolate; Q=1,4-dimethylpyridinium or tetraalkylammonium; R=Phor alkyl; X=Cl, Br, I, NCS, NCSe, or N₃] have been obtained by (a) from R₂SnX₂ and [Q]₂[Zn(dmit)₂] in the presence of excess QX,(b) from halide exchange reactions in acetone solution between [Q] [R₂SnCl(dmit)]and a halide or pseudohalide source, or (c) by addition of QX to [R₂Sn(dmit)]. Crystalstructure determinations of [NEt₄] [Ph₂SnI(dmit)] and [1,4-Me₂pyridiniuml [Ph₂SnBr(dmit)] as well as of the mixed halides, [1a, 1b, 4a, 2] [Ph₂SnCl_nI₁₋n(dmit)] (n=0.57, 0.42 or0.22), indicated that the tin atoms have distorted trigonal bipyramidal geometries in the anions,with the X ligand and a dithiolato atom in the axial sites. The [R₂SnX(dmit)]⁻ anions remain essentially intact in organic solvents, but lose X⁻ on extractionwith H₂O to give the neutral species, R₂Sn(dmit).     

Mehrkernige Molybdän- und Wolframkomplexe mit Schwefel- und Dithiophosphinatoliganden

Polynuclear Molybdenum and Tungsten Complexes with Sulfur and Dithiophosphinato Ligands Reaction of Mo(CO)₆ and disulfane [R₂P(S)]₂S₂ (R: Et, Pr, Bu) gives disulfidobridged cluster chelates [Mo₃S₇(R₂PS₂)₃]⁺ [R₂PS₂]^? 1 , the anions of which can be easily exchanged. From 1 and Ph₃P sulfido-bridged non-electrolytes [Mo₃S₄(R₂PS₂)₄] 2 are obtained, in which two Mo are additionally bridged by one R₂PS₂^?. By treatment of 2 with S₈ or disulfane 1 is regenerated. As in the conversion 1 ? 2 the formal oxidation state of Mo remains unchanged this process can be reduced to the redox reaction S₂^2? ? 1/8 S₈ + S^2?, which takes place under maintenance of the Mo₃ skeleton. Compounds 2 are coordinatively unsaturated and give 1:1 adducts with pyridine. Under modified reaction conditions M(CO)₆ and disulfane form binuclear complexes Mo₂S₄(R₂PS₂)₂ 3 resp. W₂S₄(R₂PS₂)₂ 4 , of which only 3 undergoes further reaction with M(CO)₆ and disulfane leading to 1 . The results of structural and spectroscopic investigations are reported and discussed.     

Crystal Engineering with Oxo‐ and Cyanocarbon Anions: Synthesis and Structural Characterization of Triorganotin(IV) Pentacyanopropenides and Hexacyanoazapentadienides

The first triorganotin(IV) pentacyanopropenides, [R₃Sn(H₂O)₂][C₃(CN)₅] (R = Me ( 2 ), nBu ( 3 ), Ph ( 4 ) were prepared by treatment of Ag[C₃(CN)₅] ( 1 ) with equimolar amounts of R₃SnCl in reagent grade THF. In a similar manner, dark red [R₃Sn(H₂O)₂][N{C(CN)C(CN)₂}₂] ( 6 ) containing the hexacyanoazapentadienyl anion was prepared in 55 % yield. The molecular structure of [Ph₃Sn(H₂O)₂][C₃(CN)₅] ( 4 ) was determined by X‐ray diffraction. The crystal structure consists of separated trigonal‐bipyramidal [Ph₃Sn(H₂O)₂]⁺ cations and nearly planar [C₃(CN)₅]^– anions which are linked through O–H ··· N hydrogen bonds to give a three‐dimensional network.     

Reaktionen des Gallium‐haltigen Heterocyclus [Me2Ga{HNC(Me)}2CCN]

Reactions of the Gallium‐containing Heterocycle [Me₂Ga{HNC(Me)}₂CCN] The reaction of [Me₂Ga{HNC(Me)}₂CCN] ( 1 ) with fac‐[Mo(CO)₃(MeCN)₃] leads after addition of TMEDA to the molybdenum complex fac‐[Mo(CO)₃( 1 )(TMEDA)] ( 2 ). Under identical reaction conditions with fac‐[W(CO)₃(MeCN)₃] only the tetracarbonyle complex [W(CO)₄(TMEDA)] ( 3 ) could be isolated. Treatment of dilithiated 1 with Me₂SiCl₂ or InCl₃ initiate a fragmentation of the skeleton in 1 . Obtained were the salt [Me₂Ga(TMEDA)][Me₂GaCl₂] ( 4 ) and the indium complex [Me₂InCl(TMEDA)] ( 5 ), respectively. 2 — 5 were investigated by spectroscopical and spectrometrical methods as well as by X‐ray structure determinations. According to these 1 occupies a facial site in 2 by donation of the N‐Atom from the NC group in 1 . The molecules 2 are forming a network of hydrogen bonds. In 3 , the TMEDA ligand acts as an intramolecular chelate ligand. In the salt 4 , the cation as well as the anion are coordinated in a distorted tetrahedral environment, while in 5 a distorded trigonal‐bipyramidal coordination‐sphere is present, leading to a elongated In1‐Cl1 distance of 261.74(9) pm.     

Anionic carbonyl complexes of the group VI transition metals with sulfur containing ligands

Anionic complexes of the type [M(CO)₄(dpet)]^? (where M is Cr, Mo or W and dpet is the anion of 2-(diphenylphosphino)ethanthiol) are readily prepared by the reaction of the Tl(dpet) and [M(CO)₅X]^? anions (X = halogen). These complex anions appear to have the normal octahedral geometry with the dpet ligand coordinated through both the P and S atoms. When treated with methyl or allyl halides, neutral complexes of the type M(CO)₄(dpet—R) are formed (where R is an allyl or methyl group now bound to the sulfur atom). By treating Tl^I salts of o-aminothiophenol (atp), o-methylmercaptophenol (nmp) and methylxanthic acid (mxt), with [M(CO)₅]^? anions, the respective complexes [M(CO)₄(atp)]^?, [M(CO)₄(mmp)]^? and [M(CO)₅(mxt)]^? are formed.     

Lewis Acid-Promoted Oxidative Addition at a [Ni0(diphosphine)2] Complex: The Critical Role of a Secondary Coordination Sphere

Oxidative addition represents a critical elementary step in myriad catalytic transformations. Here, the importance of thoughtful ligand design cannot be overstated. In this work, we report the intermolecular activation of iodobenzene (PhI) at a coordinatively saturated 18-electron [Ni⁰(diphosphine)₂] complex bearing a Lewis acidic secondary coordination sphere. Whereas alkyl-substituted diphosphine complexes of Group 10 are known to be unreactive in such reactions, we show that [Ni⁰(P₂B^Cy₄)₂] (P₂B^Cy₄=1,2-bis(di(3-dicyclohexylboraneyl)-propylphosphino)ethane) is competent for room-temperature PhI cleavage to give [Ni^II(P₂B^Cy₄)(Ph)(I)]. This difference in oxidative addition reactivity has been scrutinized computationally – an outcome that is borne out in ring-opening to provide the reactive precursor – for [Ni⁰(P₂B^Cy₄)₂], a “boron-trapped” 16-electron κ¹-diphosphine Ni(0) complex. Moreover, formation of [Ni^II(P₂B^Cy₄)(Ph)(I)] is inherent to the P₂B^Cy₄ secondary coordination sphere: treatment of the Lewis adduct, [Ni⁰(P₂B^Cy₄)₂(DMAP)₈] with PhI provides [Ni^II(P₂B^Cy₄)₂(DMAP)₈(I)]I via iodine-atom abstraction and not a [Ni^II(Ph)(I)(diphosphine)] compound – an unusual secondary sphere effect. Finally, the reactivity of [Ni⁰(P₂B^Cy₄)₂] with 4-iodopyridine was surveyed, which resulted in a pyridyl-borane linked oligomer. The implications of these outcomes are discussed in the context of designing strongly donating, and yet labile diphosphine ligands for use in a critical bond activation step relevant to catalysis.     

Electrochemical Investigations Give Some Insights into the Coordination Chemistry of New Stable Iridium(+1), Iridium(0), and Iridium(−1) Complexes

The redox chemistry of the stable tetracoordinated 16 valence electron d⁸‐[Ir^+I(tropp^Ph)₂]⁺(PF₆)^? and pentacoordinated 18 valence d⁸‐[Ir^+I(tropp^Ph)₂Cl] complexes was investigated by cyclic voltammetry (tropp^Ph=dibenzotropylidenyl phosphine). The experiments were performed using a platinum microelectrode varying scan rates (100 mV/s–10 V/s) and temperatures (? 40 to 20 °C) in tetrahydrofuran, THF, or acetonitrile, ACN, as solvents. In THF, the overall two‐electron reduction of the 16 valence electron d⁸‐[Ir^+I(tropp^Ph)₂]⁺(PF₆)^? proceeds in two well separated slow heterogeneous electron transfer steps according to: d⁸‐[Ir^+I (tropp^Ph)₂]⁺+e^?→d⁹‐[Ir⁰(tropp^Ph)₂]+e^?→d¹⁰‐[Ir^?I(tropp^Ph)₂]^?, [k^s₁=2.2×10^?3 cm/s for d⁸‐Ir^+I/d⁹‐Ir⁰ and k^s₂=2.0×10^?3 cm/s for d⁹‐Ir⁰/d¹⁰‐Ir^?I]. In ACN, the two redox waves merge into one “two‐electron” wave [k^s_1,2=7.76×10^?4 cm/s for d⁸‐Ir^+I/d⁹‐Ir⁰ and d⁹‐Ir⁰/d¹⁰‐Ir^?I] most likely because the neutral [Ir⁰(tropp^Ph)₂] complex is destabilized. At low temperatures (ca. ? 40 °C) and at high scan rates (ca. 10 V/s), the two‐electon redox process is kinetically resolved. In equilibrium with the tetracoordianted complex [Ir^+I(tropp^Ph)₂]⁺ are the pentacoordinated 18 valence [Ir^+I(tropp^Ph)₂L]⁺ complexes (L=THF, ACN, Cl^?) and their electrochemical behavior was also investigated. They are irreversibly reduced at rather high negative potentials (? 1.8 to ? 2.4 V) according to an ECE mechanism 1) [Ir^+I(tropp^Ph)₂(L)]+e^?→[Ir⁰(tropp^Ph)₂(L)]; 2) [Ir⁰(tropp^Ph)₂(L)]→[Ir(tropp^Ph)₂]+L, iii) [Ir⁰(tropp^Ph)₂]+e^?→[Ir^?I(tropp^Ph)₂]^?. Since all electroactive species were isolated and structurally characterized, our measurements allow for the first time a detailed insight into some fundamental aspects of the coordination chemistry of iridium complexes in unusually low formal oxidation states.     

Synthesis and Properties of the Weakly Coordinating Anion [Me3NB12Cl11]−

The weakly coordinating anion [Me₃NB₁₂Cl₁₁]^? has been prepared by a simple two‐step procedure. The anion [Me₃NB₁₂Cl₁₁]^? is easily obtained in batches of up to 20 g by chlorination of the known [H₃NB₁₂H₁₁]^? anion with SbCl₅ at about 190 °C and subsequent N‐methylation with methyl iodide. Starting from Na[Me₃NB₁₂Cl₁₁], several synthetically useful salts with reactive cations ([NO]⁺, [Ph₃C]⁺, and [(Et₃Si)₂H]⁺) were prepared. Full spectroscopic (NMR, IR, Raman, TGA, MS) characterization and single‐crystal X‐ray diffraction studies confirmed the identity and purity of the products. The thermal, chemical, and electrochemical stability as well as the basicity of the [Me₃NB₁₂Cl₁₁]^? anion is similar to that of the structurally related weakly coordinating 1‐carba‐closo‐dodecaborate and closo‐dodecaborate anions. The facile preparation of the [Me₃NB₁₂Cl₁₁]^? anion and its ideal chemical and physical properties make it a cheap alternative to other classes of weakly coordinating anions.     

Negative ion chemical ionization mass spectrometry—binding of molecules to bromide and iodide anions

The analytical potential of negative ion chemical ionization (NICI) mass spectrometry utilizing dibromodifluoro-methane (CF₂Br₂) and iodomethane (CH₃I)/methane (CH₄) as reagent gases is examined. The NICI mass spectrum of CF₂Br₂ contains Br^?, [HBr₂]^? and [CF₂Br₃]^? anions. Weak acids (i.e. those acids with approximately ΔH°_(acid) values between 1674 and 1464 kJ mol^?1) react with Br^? to produce minor yields of the hydrogen?bonded bromide attachment [MH + Br]^? anion or are unreactive. Strong acids (i.e. those acids with approximately ΔH°_(acid) > 1464 kJ mol^?1) produce primarily [MH + Br]^? anions with a minor yield of proton transfer [M ? H]^? anion. The NICI spectrum of CH₃I/CH₄ is dominated by I^?. Weak acids react with I^? to yield minor amounts of [MH + 1]^? or are unreactive. Strong acids produce only [MH + l]^? anions. From a consideration of the gas-phase basicity of the halide anion and the binding energy of the hydrogen-bonded halide attachment adduct, thermochemical data are used as a potential guide to rationalize or predict the ions observed in NICI mass spectra.     

Substitution reactions of some polynuclear carbonyl anions

The reactions of [FeCo₃(CO)₁₂]^- and [MnFe₂(CO)₁₂]^- with a number of monodentate phosphorus donor ligands (L) are reported, and complexes of the type [FeCo₃(CO)₁₁L]^- and [MnFe₂(CO)₁₁L]^- have been isolated and characterised. Only with Ph₂PCH₂CH₂PPh₂ (DPPE) was it possible to replace more than one CO group, the complex [FeCo₃(CO)₁₀(DPPE)]^- being obtained. Protonation of the ironcobalt anions leads to the neutral hydrido clusters and is accompanied by a large kinetic isotope effect, although not as large as for [FeCo₃(CO)₁₂]^- itself. The reaction of [FeCo₃(CO)₁₂]^- with Ph₂C₂ gives [FeCo₃(CO)₁₀(Ph₂C₂)]^-.     

Synthesis and redox behaviour of the chalcogenocarbonyl dianions [(E)C(PPh(2)S)(2)](2-): formation and structures of chalcogen-chalcogen bonded dimers and a novel selone

The lithium salts of the chalcogenocarbonyl dianions [(E)C(PPh₂S)₂]^2? (E=S ( 4 b ), Se ( 4 c )) were produced through the reactions between Li₂[C(PPh₂S)₂] and elemental chalcogens in the presence of tetramethylethylenediamine (TMEDA). The solid‐state structure of {[Li(TMEDA)]₂[(Se)C(PPh₂S)₂]}—[{Li(TMEDA)}₂ 4 c ]—was shown to be bicyclic with the Li⁺ cations bis‐S,Se‐chelated by the dianionic ligand. One‐electron oxidation of the dianions 4 b and 4 c with iodine afforded the diamagnetic complexes {[Li(TMEDA)]₂[(SPh₂P)₂CEEC(PPh₂S)₂]} ([Li(TMEDA)]₂ 7 b (E=S), [Li(TMEDA)]₂ 7 c (E=Se)), which are formally dimers of the radical anions [(E)C(PPh₂S)₂]^{? .} (E=S ( 5 b ), Se ( 5 c )) with elongated central E? E bonds. Two‐electron oxidation of the selenium‐containing dianion 4 c with I₂ yielded the LiI adduct of a neutral selone {[Li(TMEDA)][I(Se)C(PPh₂S)₂]}—[{LiI(TMEDA)} 6 c ]—whereas the analogous reaction with 4 b resulted in the formation of 7 b followed by protonation to give {[Li(TMEDA)][(SPh₂P)₂CSS(H)C(PPh₂S)₂]}—[Li(TMEDA)] 8 b . Attempts to identify the transient radicals 5 b and 5 c by EPR spectroscopy in conjunction with DFT calculations of the electronic structures of these paramagnetic species and their dimers are also described. The crystal structures of [{Li(TMEDA)}₂ 4 c ], [{LiI(TMEDA)} 6 c ] ? C₇H₈, [Li(TMEDA)]₂ 7 b? (CH₂Cl₂)_0.33, [Li(THF)₂]₂ 7 b , [Li(TMEDA)]₂ 7 c , [Li(TMEDA)] 8 b? (CH₂Cl₂)₂ and [Li([12]crown‐4)₂] 8 b were determined and salient structural features are discussed.     

Periphere Anbindung von Quecksilber(II)-iodid an dreikernige Molybdän-Schwefel-Dithiophosphinatocluster: [Mo3S4(R2PS2)4HgI2] (R = Et,Pr)

Peripheral Bonding of Mercury(II) Iodide to Trinuclear Molybdenum-Sulfur-Dithiophosphinato Clusters: [Mo₃S₄(R₂PS₂)₄HgI₂] (R = Et, Pr) Reaction of Mo₃S₄(R₂PS₂)₄ 1 (a : R = Et, b : R = Pr) with HgI₂ in THF yields the diamagnetic title complexes [Mo₃S₄(R₂PS₂)₄HgI₂] 3 . The crystal structure of [ 3a (H₂O)] · 2 CH₂Cl₂ shows the complexes to consist of a triangular array of Mo atoms which are bridged by μ₂? S atoms and capped by a μ₃? S atom. Each of the Mo atoms is chelated by a dithiophosphinato ligand Et₂PS₂^? and in addition two Mo atoms are bridged by a Et₂PS₂^? ligand while the H₂O molecule is bonded weakly to the third Mo atom. Thus, all Mo atoms reveal a distorted octahedral coordination sphere. HgI₂ is ?peripherally”? bonded to the cluster via two S atoms, one of which belongs to a chelating ligand and the other one to the bridging ligand. Space group P1 , lattice constants a = 12.157(2), b = 15.284(3), c = 16.049(3) Å, α = 115.56(1), β = 107.35(1), and γ = 94.62(1)°; Z = 2, d_calc = 2.23 mg/mm³; 4 236 observed reflections, R = 0.068. In organic solvents complexes 3 are strong electrolytes. VT-³¹P NMR data suggest a stepwise dissociation of 3 with formation of [Mo₃S₄(R₂PS₂)₃] ⁺[(R₂PS₂)HgI₂]^? and elimination of the bridging ligand from the cluster.     

Halide Abstraction by Na[B{C6H3(CF3)2‐3,5}4]: Synthesis and Structural Characterization of the Rhodium(I) Cations [(η6‐arene)Rh(PPh3)2]+ (Arene = benzene,toluene)

Halide abstraction from [(Ph₃P)₂Rh(μ‐Cl)]₂ by the sodium salt of the weakly coordinating [BAr^f₄]^? anion [Ar^f = C₆H₃(CF₃)₂‐3,5] in the presence of excess arene offers a convenient, high‐yielding route to the half‐sandwich cations [(arene)Rh(PPh₃)₂]⁺[BAr^f₄]^? [arene = benzene ( 1 ), toluene ( 2 )]. Crystalline samples of 1 and 2 are isomorphous [a = 13.1270(2), b = 15.3030(2), c = 17.5760(3) Å, α = 74.620(1), β = 81.533(1), γ = 88.540(1)° for 1 ] and feature the arene ligand bound to the rhodium atom in η⁶ fashion.     

Metall-Schwefelstickstoff-Verbindungen. 19. Neue Komplexe von CuI mit dem S3N−-Chelatliganden Darstellung und Struktur von [Ph4As][Cu(S3N)(CN)], [(Ph3P)2N][Cu(S3N)(S7N)] und [Ph4As]2[(S3N)Cu(S2O3)Cu(S3N)]

Metal Sulfur-Nitrogen Compounds. 19. Novel Complexes of Cu^I with the S₃N^? Chelate Ligand. Preparation and Structure of [Ph₄As][Cu(S₃N)(CN)], [(Ph₃P)₂N][Cu(S₃N)(S₇N)], and [Ph₄As]₂[(S₃N)Cu(S₂O₃)Cu(S₃N)] In alkaline media S₇NH reacts with Cu salts to yield different products. With Cu(CN) the ion [Cu(S₃N)(CN)]^? is formed, which was isolated as the [Ph₄As]⁺ salt. The crystals are monoclinic, space group P2₁/c, a = 10.499(5), b = 13.418(6), c = 18.032(8) Å, β = 91.84°(3), Z = 4. Besides the known complex ions [Cu(S₃N)₂]^? and [Cu(S₃N)Cl]^? still some more may be obtained when CuCl₂ is reacted with S₇NH: Under special conditions the S₇N ring is partly preserved, and [Cu(S₃N)(S₇N)]^? is formed. Its sparingly soluble [(Ph₃P)₂N]⁺ salt is monoclinic, space group P2₁/n, a = 9.335(6), b = 30.984(11), c = 15.108(8) Å, β = 102.87°(4), Z = 4. Using a longer reaction time a dinuclear complex [(S₃N)Cu(S₂O₃)Cu(S₃N)]^{? ?} results from the reaction of CuCl₂ with S₇NH. The two Cu atoms are bridged by an S atom of the S₂O₃^{? ?} anion. The [Ph₄As]⁺ salt of the dinuclear complex anion is triclinic, space group P1 , a = 11.226(6), b = 12.423(6), c = 19.000(10) Å, β = 76.47°(4), β = 83.98°(4), γ = 84.71°(4), Z = 2. In all these compounds the coordination of Cu^I is trigonal-planar, the S₃N^? chelate group coordinates the Cu in the usual way by two S atoms.     

Halide Abstraction from Organic Solvents in Reactions of a Copper(I) Alkoxide: Synthesis and Crystal Structures of [Cu5(dppm)(dppm−)2(OtBu)Cl2] and [Cu3(dppm)3Br2][CuBr2]

The synthesis and structures of the two Cu^I halide complexes [Cu₅(dppm)(dppm^?)₂(O^tBu)Cl₂] and [Cu₃(dppm)₃Br₂][CuBr₂] (dppm = Ph₂PCH₂PPh₂, dppm^? = [Ph₂PCHPPh₂]^?) are reported. The compounds were obtained by treating reaction mixtures of [CuO^tBu] and dppm with dichloromethane or dibromomethane.     

Zur Strukturchemie der Alkyl- und Arylhalogenoarsenate(III), [Me2As2Cl5]–, [RAsCl3]–, [R2As2Br6]2– (R = Me,Et, Ph) und [Ph2AsX2]– (X = Cl,Br)

Structural Chemistry of the Alkyl- and Arylhaloarsenates(III) [Me₂As₂Cl₅]^–, [RAsCl₃]^–, [R₂As₂Br₆]^2– (R = Me, Et, Ph) and [Ph₂AsX₂]^– (X = Cl, Br) The alkyl- and arylhaloarsenates(III) [Ph₄P][Me₂As₂Cl₅] ( 1 ), [Ph₄P][RAsCl₃] (R = Me, Et, Ph, 2 – 4 ), [Me₃PhN][PhAsCl₃] ( 5 ), [Ph₄P]₂[R₂As₂Br₆] (R = Me, Et, Ph, 6 – 8 ), [n-Pr₄N][Ph₂AsCl₂] ( 9 ) and [n-Bu₄N][Ph₂AsBr₂] ( 10 ) have been prepared and their structures established by X-ray diffraction. In contrast to the chloroarsenates(III) 2 – 5 , which all contain isolated ψ-trigonal bipyramidal anions [RAsCl₃]^–, the analogous bromoarsenates(III) 6 – 8 exhibit dimeric structures. Whereas the trans sited As–Cl distances in 2 and 3 are very similar a pronounced degree of asymmetry is apparent for the Cl–As–Cl three-centre bonds in 4 and 5 [2.396(1) and 2.602(1) Å in 5]. In 6 and 7 C_i symmetry related RAsBr₂ units are connected through long As…Br bonds [2.926(1) and 3.116(2) Å in 6 ]. The bromophenylarsenate(III) anion of 8 which contains two effectively undistorted ψ-trigonal bipyramids [PhAsBr₃]^– associated by weak As…Br interactions [3.117(2) Å]. In view of its very long bridging As…Cl distances the [Me₂As₂Cl₅]^– anion in 1 can, as 6 an 7 , be regarded as two MeAsCl₂ molecules weakly linked through a chloride ion.     

Salts of HCN‐Cyanide Aggregates: [CN(HCN)2]− and [CN(HCN)3]−

Although pure hydrogen cyanide can spontaneously polymerize or even explode, when initiated by small amounts of bases (e.g. CN^?), the reaction of liquid HCN with [WCC]CN (WCC=weakly coordinating cation=Ph₄P, Ph₃PNPPh₃=PNP) was investigated. Depending on the cation, it was possible to extract salts containing the formal dihydrogen tricyanide [CN(HCN)₂]^? and trihydrogen tetracyanide ions [CN(HCN)₃]^? from liquid HCN when a fast crystallization was carried out at low temperatures. X‐ray structure elucidation revealed hydrogen‐bridged linear [CN(HCN)₂]^? and Y‐shaped [CN(HCN)₃]^? molecular ions in the crystal. Both anions can be considered members of highly labile cyanide‐HCN solvates of the type [CN(HCN)_n]^? (n=1, 2, 3 …) as well as formal polypseudohalide ions.     

Some observations on the systems Co2(CO)8/sodium amalgam and Hg[Co(CO)4]2/sodium amalgam,and the effect of added LiBr

Co₂(CO)₈ and Hg[Co(CO)₄]₂ react sodium amalgam and/or mercury in ethereal solvents to give a variety of products. On treatment with aqueous M(o-phen)₃Cl₂(M  Fe, Ni), the anions [Co(CO)₄^?, [Co₃(CO)₁₀]^?, {Hg[Co(CO)₄]₃}^? and {Hg[Co(CO)₄]₂Cl}^? could be isolated as their [M(o-phen)₃]²⁺ salts. The effect of LiBr on the reacting systems was also investigated and the anion {Hg[Co(CO)₄]₂Br}^? isolated.     

Synthesis and structure of the platinum complexes [Bu4N]+[PtBr5(DMSO)]?, [Ph4P]+[PtBr5(DMSO)]?, and [Ph3(n-Am)P]+[PtBr5(DMSO)]?

The complexes [Bu₄N]₂⁺[PtBr₆]²⁻ (I), [Ph₄P]₂⁺[PtBr₆]²⁻ (II), and [Ph₃(n-Am)P]₂⁺ (III) are synthesized by the reactions of tetrabutylammonium bromide, tetraphenylphosphonium bromide, and triphenyl(n-amyl)-tetraphenylphosphonium bromide, respectively, with potassium hexabromoplatinate (mole ratio 2: 1). After recrystallization from dimethyl sulfoxide, complexes I, II, and III transform into [Bu₄N]⁺[PtBr₅(DMSO)]⁻ (IV), [Ph₄P]⁺[PtBr₅(DMSO)]⁻ (V), and [Ph₃(n-Am)P]⁺[PtBr₅(DMSO)]⁻ (VI). According to the X-ray diffraction data, the cations of complexes IV–VI have a slightly distorted tetrahedral structure. The N-C and P-C bond lengths are 1.492(7)–1.533(6) and 1.782(10)–1.805(10) ?, respectively. The platinum atoms in the mononuclear anions are hexacoordinated. The dimethyl sulfoxide ligands are coordinated with the Pt atom through the sulfur atom (Pt-S 2.3280(18)–2.3389(11) ?). The Pt-Br bond lengths are 2.4330(6)–2.4724(6) ?.     

Anionic Gold(I) Complexes—Twelve‐ and Ten‐Vertex Monocarba‐closo‐borate Anions with Carbon–Gold σ Bonds

The anionic gold(I) complexes [1‐(Ph₃PAu)‐closo‐1‐CB₁₁H₁₁]^? ( 1 ), [1‐(Ph₃PAu)‐closo‐1‐CB₉H₉]^? ( 2 ), and [2‐(Ph₃PAu)‐closo‐2‐CB₉H₉]^? ( 3 ) with gold–carbon 2c–2e σ bonds have been prepared from [AuCl(PPh₃)] and the respective carba‐closo‐borate dianion. The anions have been isolated as their Cs⁺ salts and the corresponding [Et₄N]⁺ salts were obtained by salt metathesis reactions. The salt Cs‐ 3 isomerizes in the solid state and in solution at elevated temperatures to Cs‐ 2 with ΔH_iso=(?75±5) kJ mol^?1 (solid state) and ΔH^≠=(118±10) kJ mol^?1 (solution). The compounds were characterized by vibrational and multi‐NMR spectroscopies, mass spectrometry, elemental analysis, and differential scanning calorimetry. The crystal structures of [Et₄N]‐ 1 , [Et₄N]‐ 2 , and [Et₄N]‐ 3 were determined. The bonding parameters, NMR chemical shifts, and the isomerization enthalpy of Cs‐ 3 to Cs‐ 2 are compared to theoretical data.