The [Ag{Se2C2(CN)2}(Se6)]3−, [Sb{Se2C2(CN)2}2]3−, and [As(Se)3(CH2CN)]2− Anions: Facile Formation of the Maleonitrilediselenolate (mns) Ligand, [Se2C2(CN)2]2−

An unusual route to the maleonitrilediselenolate (mns) ligand has been discovered with the isolation of compounds that contain this ligand bound to silver (structure shown on the right) or antimony. The formation of the [As(Se)₃(CH₂CN)]²⁻ anion along with possible pathways to the mns ligands is discussed.     

Anionische Nickel-Pseudohalogenid-Komplexe der Typen [Ni{N(CN)2}3]− und [Ni{N(CN)2}2(NCS)2]2−

Anionie Nickel Pseudohalide Complexes of the Types [Ni{N(CN)₂}₃]^? and [Ni{N(CN)₂}₂(NCS)₂]^2? The preparation of a new type of anionic pseudohalide complexes of nickel [Ni{N(CN)₂}₃]^? and of mixed thiocyanate-dicyanamide complexes [Ni{N(CN)₂}₂(NCS)₂]^2? is reported. The structures of the complexes are discussed on the basis of IR- and magnetic measurements. The new compounds are representing polymer octahedral complexes with a bridging function of the dicyanamide ligands.     

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.     

Manganese(II) Complexes with Bridging Selenidoarsenate(III) Anions [AsSe2(Se2)]3− and [(AsSe2)2(μ‐Se2)]4−

Solvothermal reaction of [MnCl₂(terpy)] with elemental As and Se at a 1:1:2 molar ratio in H₂O/trien (10:1) at 150 °C affords the linear trimanganese(II) complex [{Mn(terpy)}₃(μ‐AsSe₄)₂] ( 1 ). The tridentate [AsSe₂(Se₂)]^3? anions of 1 chelate the terminal {Mn(terpy)}²⁺ fragments and bridge these through their remaining Se atom to the central {Mn(terpy)}²⁺ moiety. Weak interactions of Mn1···Se and Mn3···Se bonds with length 2.914(7) and 3.000(7) Å link the molecules of 1 into infinite chains. Treatment of [MnCl₂(cyclam)]Cl with As and Se at a 1:1:2 molar ratio in superheated H₂O/CH₃OH (1:1) at 150 °C yields the dinuclear complex [{Mn(cyclam)}₂ (μ‐As₂Se₆)] ( 2 ), whose novel [(AsSe₂)₂(μ‐Se₂)]^4? ligands bridge the Mn^II atoms in a μ‐1κ²Se¹, Se²: 2κ²Se⁵,Se⁶ manner.     

Dinuclear Manganese(II) Complexes with Bridging Selenidodiarsenate Anions [As2Se4]4−, [As2Se5]4− and [As2Se6]2−

Solvothermal reaction of [MnCl₂(amine)] (amine = terpy and tren) with elemental As and Se at a 1:1:2 molar ratio in H₂O/tren (10:1) affords the dimanganese(II) complexes [{Mn(terpy)}₂(μ‐As₂Se₄)] ( 1 ) and [{Mn(tren)}₂(μ‐As₂Se₅)] ( 2 ) respectively. The tetradentate [As₂Se₄]^4? bridging ligands in 1 contain a central As–As bond and exhibit approximately C_2h symmetry. Pairs of gauche sited Se atoms participate in five‐membered As₂Se₂Mn chelate rings. In contrast, two AsSe₃ pyramids share a common corner in the [As₂Se₅]^4? ligands of 2 and each coordinates an [Mn(tren)]²⁺ fragment through a single terminal Se atom. Such dinuclear complexes are linked into tetranuclear moieties through weak Se···Mn interactions of length 3.026(3) Å involving one of these terminal Se atoms. At a 1:3:6 molar ratio, solvothermal reaction of [MnCl₂(tren)] with As and Se leads to formation of a second dinuclear complex [{Mn(tren)}₂(μ‐As₂Se₆)₂] ( 3 ), which contains two bridging bidentate [As₂Se₆]^2? ligands. These are cyclic with an As₂Se₄ ring and can be regarded as being derived from [As₂Se₅]^4? anions by formation of two Se‐Se bonds to an additional Se atom.     

Zum IR-Spektrum des Nitrosodicyanmethanid-Ions [ONC(CN)2]−

The infrared spectrum of [ONC(CN)₂]^? is described and an assignment is given. In order to facilitate this assignment, ₁₅N is used. Complexes, formed by this anion, are also investigated by means of IR spectroscopy. The shift of the bands of the anion are reported and a discussion concerning the bonding relations of the complexes is given. Some remarkable isotopic effects are mentioned.     

Palladium(II) and Platinum(II) Complexes with Bisphosphanes, [S2C=C(CN)2]2– and [Se2C=C(CN)2]2– as Chelating Ligands

The palladium(II) and platin(II) 1, 1‐dicyanoethylene‐2, 2‐dithiolates [(L–L)M{S₂C=C(CN)₂}] (M = Pd: L–L = dppm, dppe, dcpe, dpmb; M = Pt: dppe, dcpe, dpmb) were prepared either from[(L–L)MCl₂] and K₂[S₂C=C(CN)₂] or from [(PPh₃)₂M{S₂C=C(CN)₂}] and the bisphosphane. Moreover, [(dppe)Pt{S₂C=C(CN)₂}]was obtained from [(1, 5‐C₈H₁₂)Pt{S₂C=C(CN)₂}] and dppeby ligand exchange. The 1, 1‐dicyanoethylene‐2, 2‐diselenolates[(dppe)M{Se₂C=C(CN)₂}] (M = Pd, Pt) were prepared from[(dppe)MCl₂] and K₂[Se₂C=C(CN)₂]. The oxidation potentials of the square‐planar palladium and platinum complexes were determined by cyclic voltammetry. The reaction of [(dcpe)Pd(S₂C=O)] with TCNE led to a ligand fragment exchange and gave the 1, 1‐dicyanoethylene‐2, 2‐dithiolate [(dcpe)Pd{S₂C=C(CN)₂}] in good yield.     

Synthesis and characterization of the silver maleonitrilediselenolates and silver maleonitriledithiolates [K([2.2.2]-cryptand)]4[Ag4(Se2C2(CN)2)4], [Na([2.2.2]-cryptand)]4[Ag4(S2C2(CN)2)4].0.33MeCN, [NBu4]4[Ag4(S2C2(CN)2)4], [K([2.2.2]-cryptand)]3[Ag(Se2C2(CN)2)2].2MeCN, and [Na([2.2.2]-cryptand)]3[Ag(S2C2(CN)2)2

Reaction of AgBF(4), KNH(2), K(2)Se, Se, and [2.2.2]-cryptand in acetonitrile yields [K([2.2.2]-cryptand)](4)[Ag(4)(Se(2)C(2)(CN)(2))(4)] (1). In the unit cell of 1 there are four [K([2.2.2]-cryptand)](+) units and a tetrahedral Ag(4) anionic core coordinated in mu(1)-Se, mu(2)-Se fashion by each of four mns ligands (mns = maleonitrilediselenolate, [Se(2)C(2)(CN)(2)](2)(-)). Reaction of AgNO(3), Na(2)(mnt) (mnt = maleonitriledithiolate, [S(2)C(2)(CN)(2)](2)(-)), and [2.2.2]-cryptand in acetonitrile yields [Na([2.2.2]-cryptand)](4)[Ag(4)(mnt)(4)].0.33MeCN (2). The Ag(4) anion of 2 is analogous to that in 1. Reaction of AgNO(3), Na(2)(mnt), and [NBu(4)]Br in acetonitrile yields [NBu(4)](4)[Ag(4)(mnt)(4)] (3). The anion of 3 also comprises an Ag(4) core coordinated by four mnt ligands, but the Ag(4) core is diamond-shaped rather than tetrahedral. Reaction of [K([2.2.2]-cryptand)](3)[Ag(mns)(Se(6))] with KNH(2) and [2.2.2]-cryptand in acetonitrile yields [K([2.2.2]-cryptand)](3)[Ag(mns)(2)].2MeCN (4). The anion of 4 comprises an Ag center coordinated by two mns ligands in a tetrahedral arrangement. Reaction of AgNO(3), 2 equiv of Na(2)(mnt), and [2.2.2]-cryptand in acetonitrile yields [Na([2.2.2]-cryptand)](3)[Ag(mnt)(2)] (5). The anion of 5 is analogous to that of 4. Electronic absorption and infrared spectra of each complex show behavior characteristic of metal-maleonitriledichalcogenates. Crystal data (153 K): 1, P2/n, Z = 2, a = 18.362(2) A, b = 16.500(1) A, c = 19.673(2) A, beta = 94.67(1) degrees, V = 5941(1) A(3); 2, P4, Z = 4, a= 27.039(4) A, c = 15.358(3) A, V = 11229(3) A(3); 3, P2(1)/c, Z = 6, a = 15.689(3) A, b = 51.924(11) A, c = 17.393(4) A, beta = 93.51(1) degrees, V = 14142(5) A(3); 4, P2(1)/c, Z = 4, a = 13.997(1) A, b = 21.866(2) A, c = 28.281(2) A, beta = 97.72(1) degrees, V = 8578(1) A(3); 5, P2/n, Z = 2, a = 11.547(2) A, b = 11.766(2) A, c = 27.774(6) A, beta = 91.85(3) degrees, V = 3772(1) A(3).     

Pseudoelementverbindungen. II. Quantenchemische Untersuchungen an pseudoelementmodifizierten Nitrit-Ionen [EO2−nYn]− (E = N,C(CN); Y = C(CN)2)

Pseudoelement Compounds. II. Quantum Chemical Studies on Pseudoelement Modified Nitrite Ions [EO_2?nY_n]^? (E = N, C(CN); Y = C(CN)₂) The electronic structure and the ambidence of pseudochalcogen modified nitrite ions are discussed on the basis of a quantum chemical MNDO study in connection with structural, ESCA and ¹³C NMR data.     

The Hexacyanodiborane(6) Dianion [B2(CN)6]2−

Diborane(6) dianions with substituents that are bonded to boron via carbon are very reactive and therefore only a few examples are known. Diborane(6) derivatives are the simplest catenated boron compounds with an electron‐precise B–B σ‐bond that are of fundamental interest and of relevance for material applications. The homoleptic hexacyanodiborane(6) dianion [B₂(CN)₆]²⁻ that is chemically very robust is reported. The dianion is air‐stable and resistant against boiling water and anhydrous hydrogen fluoride. Its salts are thermally highly stable, for example, decomposition of (H₃O)₂[B₂(CN)₆] starts at 200 °C. The [B₂(CN)₆]²⁻ dianion is readily accessible starting from 1) B(CN)₃²⁻ and an oxidant, 2) [BF(CN)₃]⁻ and a reductant, or 3) by the reaction of B(CN)₃²⁻ with [BHal(CN)₃]⁻ (Hal=F, Br). The latter reaction was found to proceed via a triply negatively charged transition state according to an S_N2 mechanism.