Synthese,Struktur und Photolyse von Isocyanatokomplexen des Rheniums

Synthesis, Structure, and Photolysis of Isocyanato Complexes of Rhenium The Re^III isocyanato complex Re(NCO)₃(PMe₂Ph)₃ yields from the reaction of ReCl₃(PMe₂Ph)₃ with an excess of NaOCN in EtOH. It crystallizes in the triclinic space group P 1 with a = 991.8(6), b = 1180.7(6), c = 1348.8(5) pm, α = 89.85(1)°, β = 94.12(1), γ = 111.56(1)°, Z = 2. In the mononuclear complex with an octahedral coordination of the Re atoms the phosphine and isocyanato ligands exhibit a meridional arrangement. By using a deficient amount of NaOCN the mono isocyanato complex Re(NCO)Cl₂(PMe₂Ph)₃ is formed, and part of the educt is transformed to its isomer [(Me₂PhP)₃Re(μ-Cl)₃Re(PMe₂Ph)₃]Cl₃. The mono isocyanato complex forms monoclinic crystals with the space group P2₁/n and a = 1467.5(7), b = 1310.6(7), c = 1603.2(8) pm, β = 112.08(1)°, Z = 4. The isocyanato ligand is in trans position to a Cl atom, and the phosphine ligands are coordinated in a meridional arrangement. [(Me₂PhP)₃Re(μ-Cl)₃Re(PMe₂Ph)₃]Cl₃ · 2 EtOH crystallizes in the hexagonal space group P6₃/m with a = 1332.6(2), c = 2300.1(7) pm, Z = 2. The dinuclear complex cation occupies with its center a special position with the symmetry C_3h. Photolysis of Re(NCO)Cl₂(PMe₂Ph)₃ results in the cleavage of the isocyanato ligand with release of CO and formation of the nitrido complex ReNCl₂(PMe₂Ph)₃. The reaction of ReNCl₂(PMe₂Ph)₃ with NaOCN affords the complex ReN(NCO)₂(PMe₂Ph)₃. It crystallizes in the space group P2₁/n with a = 943.0(3), b = 2635.2(4), c = 1212.6(5) pm, β = 109.88(1)°, Z = 4. In this nitrido complex, like in the educt, the phosphine ligands form a meridional arrangement. The nitrido ligand is in trans position to an isocyanato group. The distance Re≡N is 165.9(6) pm.     

Anhydrous Nitrates and Nitrosonium Nitratometallates of Manganese and Cobalt,M(NO3)2, NO[Mn(NO3)3], and (NO)2[Co(NO3)4]: Synthesis and Crystal Structure

Crystalline NO[Mn(NO₃)₃] ( I ) and (NO)₂[Co(NO₃)₄] ( II ) were synthesized by reaction of the corresponding metal and a liquid N₂O₄/ethylacetate mixture. I is orthorhombic, Pca2₁, a = 9.414(2), b = 15.929(3), c = 10.180(2) Å, Z = 4, R₁ = 0.0286. II is monoclinic, C2/c, a = 14.463(3), b = 19.154(4), c = 13.724(3) Å, β = 120.90(3), Z = 12, R₁ = 0.0890. Structure I consists of [Mn(NO₃)₃]^– sheets with NO⁺ cations between them. Two types of Mn atoms have CN_Mn = 7 and 8. Structure II is ionic containing isolated [Co(NO₃)₄]‐anions and NO⁺ cations with CN_Co = 8. Crystals of Mn(NO₃)₂ ( III ) and Co(NO₃)₂ ( IV ) were obtained by concentration of metal nitrate hydrate solutions in 100% HNO₃ in a desiccator with P₂O₅. III is cubic, Pa 3, a = 7.527(2) Å, Z = 4, R₁ = 0.0987. IV is trigonal, R 3, a = 10.500(2), c = 12.837(3) Å, Z = 12, R₁ = 0.0354. The three dimensional structure III is isotypic to the strontium and barium dinitrates. Structure IV contains a three dimensional network of interconnected Co(NO₃)_6/3 units with a distorted octahedral coordination environment of Co atoms. General correlations between central atom coordination and coordination modes of NO₃ groups are discussed.     

Coinage Metal Complexes of Bis(quinoline-2-ylmethyl)phenylphosphine-Simple Reactions Can Lead to Unprecedented Results

The different coordination behavior of the flexible yet sterically demanding, hemilabile P,N ligand bis(quinoline-2-ylmethyl)phenylphosphine ( bqmpp ) towards selected Cu^I, Ag^I and Au^I species is described. The resulting X-ray crystal structures reveal interesting coordination geometries. With [Cu(MeCN)₄]BF₄, compound 1 [Cu₂(bqmpp)₂](BF₄)₂ is obtained, wherein the copper(I) atoms display a distorted square planar and square pyramidal geometry. The steric demand and π-stacking of the ligand allow for a short Cu⋅⋅⋅Cu distance (2.588(9) Å). Cu^I complex 2 [Cu₄Cl₃(bqmpp)₂]BF₄ contains a rarely observed Cu₄Cl₃ cluster, probably enabled by dichloromethane as the chloride source. In the cluster, even shorter Cu⋅⋅⋅Cu distances (2.447(1) Å) are present. The reaction of Ag[SbF₆] with the ligand leads to a dinuclear compound ( 3 ) in solution as confirmed by ³¹P{¹H} NMR spectroscopy. During crystallization, instead of the expected phosphine complex 3 , a tris(quinoline-2-ylmethyl)bisphenyl-phosphine ( tqmbp ) compound [Ag₂(tqmbp)₂](SbF₆)₂ 4 is formed by elimination of quinaldine. The Au(I) compound [Au₂(bqmpp)₂]PF₆ ( 5 ) is prepared as expected and shows a linear arrangement of two phosphine ligands around Au^I.     

Three rare heteromultinuclear 3d-4f salamo-like complexes constructed from auxiliary ligand 4,4′-bipy: Syntheses,structural characterizations,fluorescence and antimicobial properties

Three rare heteromultinuclear complexes, _∞[NiL(4,4′-bipy)Pr (NO₃)₃]·(CH₃)₂CHOH ( 1 ), [{CuLSm (NO₃)₃}₂(4,4′-bipy)]·CH₃OH ( 2 ) and [{CuL (CH₃CH₂OH)Eu (NO₃)₃] ( 3 ) with a symmetrical salamo-like hexadentate ligand H₂L have been synthesized, and characterized by FT-IR, UV–vis and X-ray crystallography. Complex 1 is a 1D coordination polymer constructed from heterobimetallic [Ni(L)Pr (NO₃)₃] units which are connected by the exo-dentate ligand 4,4′-bipy bearing nitrogen-donor atoms. Complex 2 is a heterotetranuclear dimer based on [Cu(L)Sm (NO₃)₃] moieties which are linked through the exo-dentate 4,4′-bipy hasing nitrogen-donor atoms. Complex 3 is a heterodinuclear structure, Cu (II) atom is five-coordinate possessing a distorted square pyramidal geometry, and Eu (III) atom is a deca-coordinate adopting a distorted bicapped square antiprism. In addition, fluorescence and antimicobial properties of the ligand H₂L and its complexes 1 – 3 have also been discussed.     

Tripodal Thiols as Ligands for Molecular Magnets: Very Strong Antiferromagnetic Exchange Interactions in Vanadium(III) Clusters

The synthesis, structural and magnetic characterisation of [V^III₃O(tmme)₂(diimine)₂Cl] [diimine=2,2′‐bipyridine ( 1 ) or 1,10‐phenanthroline ( 2 )] and (HNEt₃)₂[V^III₄O(tmme)₄] ( 3 ) is reported, in which H₃tmme is tris(mercaptomethyl)ethane, MeC(CH₂SH)₃, the thiol analogue of the famous tripodal alcohol ligands typified by H₃thme [tris(hydroxymethyl)ethane, MeC(CH₂OH)₃]. Complexes 1 and 3 have “T‐shaped” and square topologies, respectively, and the latter is centred on a rare example of a square‐planar oxide. The tri‐thiolate ligands bind the periphery of the clusters and provide such strong antiferromagnetic exchange pathways that in both cases only a single total spin state is occupied up to room temperature, in the absence of metal–metal bonding. Magnetic data, electronic structure calculations and electrochemical data are reported.     

The Complexed 1,3‐Diphospha‐2‐Arsaallyl Radical and Its Cationic and Anionic Derivatives

Photolysis of [Cp*As{W(CO)₅}₂] ( 1 a ) in the presence of Mes*P?PMes* (Mes*=2,4,6‐tri‐tert‐butylphenyl) leads to the novel 1,3‐diphospha‐2‐arsaallyl radical [(CO)₅W(μ,η²:η¹‐P₂AsMes*₂)W(CO)₄] ( 2 a ). The frontier orbitals of the radical 2 a are indicative of a stable π‐allylic system that is only marginally influenced by the d orbitals of the two tungsten atoms. The SOMO and the corresponding spin density distribution of the radical 2 a show that the unpaired electron is preferentially located at the two equivalent terminal phosphorus atoms, which has been confirmed by EPR spectroscopy. The protonated derivative of 2 a , the complex [(CO)₅W(μ,η²:η¹‐P₂As(H)Mes*₂)W(CO)₄] ( 6 a ) is formed during chromatographic workup, whereas the additional products [Mes*P?PMes*{W(CO)₅}] as the Z‐isomer ( 3 ) and the E‐isomer ( 4 ), and [As₂{W(CO)₅}₃] ( 5 ) are produced as a result of a decomposition reaction of radical 2 a . Reduction of radical 2 a yields the stable anion [(CO)₅W(μ,η²:η¹‐P₂AsMes*₂)W(CO)₄]^? in 7 a , whereas upon oxidation the corresponding cationic complex [(CO)₅W(μ,η²:η¹‐P₂AsMes*₂)W(CO)₄][SbF₆] ( 8 a ) is formed, which is only stable at low temperatures in solution. Compounds 2 a , 7 a , and 8 a represent the hitherto elusive complexed redox congeners of the diphospha‐arsa‐allyl system. The analogous oxidation of the triphosphaallyl radical [(CO)₅W(μ,η²:η¹‐ P₃Mes*₂)W(CO)₄] ( 2 b ) also leads to an allyl cation, which decomposes under CH activation to the phosphine derivative [(CO)₅W{μ,η²:η¹‐P₃(Mes*)(C₅H₂tBu₂C(CH₃)₂CH₂)}W(CO)₄] ( 9 ), in which a CH bond of a methyl group of the Mes* substituent has been activated. All new products have been characterized by NMR spectrometry and IR spectroscopy, and compounds 2 a , 3 , 6 a , 7 a , and 9 by X‐ray diffraction analysis.     

Trifluoromethylsulfonyl-Based Salts of BEDT-TTF: Crystal and Electronic Structures and Physical Properties11

Three 2 : 1 salts of the organic donor molecule bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) with trifluoromethylsulfonyl-based anions N(SO₂CF₃)₂⁻, CH(SO₂CF₃)₂⁻ and C(SO₂CF₃)₃⁻ were prepared by electrocrystallization. These salts were characterized by single-crystal X-ray diffraction, electron spin resonance (ESR) spectroscopy, electrical resistivity measurements and electronic band structure calculations. (ET)₂N(SO₂CF₃)₂ is a two-dimensional (2D) metal, but its ESR spin susceptibility above 150 K shows a weakly semiconducting behavior, presumably because during ESR measurements the sample cooling rate is slow hence allowing the disordered anions to readjust their positions. (ET)₂CH (SO₂CF₃)₂ is a 2D metal and undergoes a metal-to-insulator (MI) transition at 110 K due probably to a geometry change of the donor molecule layers. (ET)₂C(SO₂CF₃)₃ is a one-dimensional (1D) metal and undergoes an MI between 180 and 240 K, which is expected to be of charge density wave type.     

Synthese und Struktur der Platin(O)-Verbindungen [(dipb)Pt]2(COD) und (dipb)3Pt2 sowie des clusters Hg6[Pt(dipb)]4 (dipb = (i-Pr)2P(CH2)4P(i-Pr)2)

Synthesis and Structure of the Platinum(0) Compounds [(dipb)Pt]₂(COD) and (dipb)₃Pt₂ and of the Cluster Hg₆[Pt(dipb)]₄ (dipb = (i-Pr)₂P(CH₂)₄P(i-Pr)₂) The reduction of (dipb)PtCl₂ with Na/Hg yields (dipb)Pt as an intermediate which reacts with the amalgam to form the cluster Hg₆[Pt(dipb)]₄ ( 3 ) or decomposes to (dipb)₃Pt₂ ( 2 ) and Pt. In the presence of COD [(dipb)Pt]₂(COD) ( 1 ) is obtained. 1 crystallizes monoclinicly in the space group P2₁/c with a = 1596.1(4), b = 996.5(2), c = 1550.4(3) pm, β = 113.65(2)°, Z = 2. In the dinuclear complex two (dipb)Pt units are bridged by a 1,2-η²-5,6-η² bonded COD ligand. Whereby the C = C double bonds are lengthened to 145 pm. 2 forms triclinic crystals with the space group P1 and a = 1002.0(2), b = 1635.9(3), c = 868.2(2) pm, α = 94.70(2)°, β = 94.45(2)°, σ = 87.95(1)°, Z = 1. In 2 two (dipb)Pt moieties are connected by a μ-dipb ligand in a centrosymmetrical arrangement. 3 is monoclinic with the space group C2/c and a = 1273.8(3), b = 4869.2(6), c = 1660.2(3) pm, β = 95.16(2)°, Z = 4. The clusters Hg₆[Pt(dipb)]₄ have the symmetry C₂. Central unit is a Hg₆ octahedron of which four faces are occupied by Pt(dipb) groups. The bonding in the cluster is discussed on the basis of eight Pt? Hg two center bonds of 267.6 pm and two Pt? Hg? Pt three center bonds with Pt? Hg = 288.0 pm.     

Dibutyltin-3-hydroxyflavone titrates a dissociable component (cofactor) of mitochondrial ATP synthase: An energy-transfer component linked to the ubiquinone pool

Dibutyltin-3-hydroxyflavone, Bu₂Sn(of), is a new fluorescence probe inhibitor of F₁F₀-ATPase and oxidative phosphorylation which inhibits by titration of an unidentified component of F₀. Its site of action is closely related to that of the trialkyltins and of venturicidin. This F₀ component is part of a pool of this component which is present in the heart mitochondrial inner membrane at levels of 5–7 nmol (mg protein)^?1 [18 ± 3 Bu₂Sn(of) sites per mol F₁F₀-ATPase]. However, ATPase activity in submitochondrial particles is near maximally inhibited by titration of approx. three Bu₂Sn(of) sites per mol F₁F₀-ATPase. Over 60% (60–80%) of the Bu₂Sn(of) interaction sites can be lost during the purification of F₁F₀-ATPase from submitochondrial particles. The number of Bu₂Sn(of) interaction sites in various F₁F₀-ATPase preparations is variable. The high numbers of Bu₂Sn(of) sites per mol F₁F₀-ATPase for heart mitochondria (18–21) and submitochondrial particles (15–19.5) decline in ATP synthase (11–15) to the low values obtained in Complex V (7–10.5) and the minimal values observed in highly purified F₁F₀?ATPase (3.5–5.6), thus indicating a variable dissociable component or cofactor of ATP synthase. The Bu₂Sn(of) interaction site, a component of ATP synthase, is responsive to the redox status of the respiratory chain and the interaction with Bu₂Sn(of) is with the reduced form of this component. Fluorescence titration studies show that this component is in redox equilibrium with the ubiquinone pool of the respiratory chain. It is proposed that this redox component serves as an inhibitor titratable cofactor pool which cycles through an F₀ interaction site (or sites) via a system which serves as an energy-transfer link between the respiratory chain and ATP synthase.     

Synthesis and Characterization of New M‐Triazole Complexes (M = Co,Cu, Zn)

Three new complexes with the ligand 3,5‐diamino‐1,2,4‐triazole (Hdatrz), [Co₃(μ₂‐Hdatrz)₆(H₂O)₆]·(NO₃)₈·4H₂O ( 1 ), [Cu₃(μ₂‐Hdatrz)₄(μ₂‐Cl)₂(H₂O)₂Cl₂]·Cl₂·4H₂O·2C₂H₅OH ( 2 ) and {[Zn₂(μ₂‐SO₄) (μ₃‐datrz)₂]·2H₂O}_n ( 3 ) have been synthesized and structurally characterized. Complex 1 has a linear trinuclear mixed‐valence cobalt structure with six neutral triazole ligands in the N(1), N(2)‐bridging mode. The central cobalt atom, Co(1), is coordinated to six nitrogen atoms (octahedral) whereas the terminal cobalt atom, Co(2), is coordinated to an N₃O₃ moiety (octahedral). In complex 1 , the uudd cyclic water clusters, nitrate anions and the trimeric cations are linked to a supramolecular structure. Complex 2 features a linear trinuclear copper(II) core, with four N(1), N(2)‐bridging triazole ligands and two chlorido bridges. The central copper atom is coordinated to an N₄Cl₂ moiety (octahedral) whereas the terminal copper is coordinated to an N₂Cl₂O moiety (square‐pyramidal). In complex 2 , tetrahedral hydrogen bonding interactions play an important role to form a supramolecular network. Complex 3 exhibits a polymeric structure, with N(1), N(2), N(4)‐bridging triazolate ligands and sulfate bridges, in which zinc is coordinated to an N₃O moiety (tetrahedral). In complex 3 , water molecules and sulfate anions construct the sulfate‐water supramolecular chain with hydrogen bonding interactions. In addition, the complexes were investigated by elemental analyses, IR spectroscopic, and thermogravimetric measurements.     

Tricarbonyl Complexes of Rhenium(I) with Acetylpyridine Benzoylhydrazone and Related Ligands

Novel rhenium(I) tricarbonyl complexes have been prepared by reactions of (Et₄N)₂[Re(CO)₃Br₃] with acetylpyridine benzoylhydrazone, Hapbhyd, di(2‐pyridyl)ketone benzoylhydrazone, Hpy₂bhyd, bis(2‐pyridine)ketone, py₂CO, and pyridinealdehyde terephtalaldehydebishydrazone, pytehyd. The ligands remain protonated when no supporting base is added and the following complexes have been isolated: [Re(CO)₃Br(Hapbhyd)], [Re(CO)₃Br(Hpy₂bhyd‐py, hyd)], [Re(CO)₃Br(Hpy₂bhyd‐py¹, py²)], [Re(CO)₃Br(py₂CO‐N, N)] and [Re(CO)₃Br(pytehyd)]. Addition of triethyl amine results in deprotonation of Hapbhyd and the formation of [Re(CO)₃(OH₂)(apbhyd)], whereas Hpy₂bhyd is hydrolysed and a rhenium complex with the monoanionic bis(2‐pyridyl)hydroxymethanolato ligand, {py₂C(OH)O}^‐, is formed. The same compound, [Re(CO)₃{py₂C(OH)O}], is obtained when triethyl amine and water are added to a mixture of (Et₄N)₂[Re(CO)₃Br₃] and py₂CO. The air‐stable products have been studied by spectroscopic methods and X‐ray crystallography.     

Zur Reaktion eines Bis(amino)germylens mit Germaniumaziden: Abfangreaktionen von instabilen Germa-Iminen

Reaction of a Cyclic Bis(amino)germylene with Germaniumazides: Trapping-Reactions of Unstable Germa-Imines . The cyclic bis(amino)germylene 1 reacts with different germaniumazides of the type Me₂Si(NtBu)₂Ge(R)N₃ (R = Me ( 2 ), tBu ( 3 ), N(SiMe₃)₂ ( 4 ), R = N₃ ( 5 )). With the exception of 4 all azides lose dinitrogen when treated with 1 and the Ge^II center coordinates the α-nitrogen of the azide group. It seems to be reasonable to assume a transient germaimine (nitride) which is trapped by further reaction with the azide molecules 2 and 5 or by reaction with the solvent pyridine ( 3 ). In the case of 2 the germatetrazole [Me₂Si(NtBu)₂]GeN₄[Ge(NtBu)₂SiMe₂]₂ ( 6 ) is formed, the tetrazole nitrogens being exclusively substituted by germanium atoms (point symmetry of the molecule C_s(m)). When 1 is treated with 5 a tris(germa)amine [Me₂Si(NtBu)₂Ge(N₃)]₃N ( 8 ) is formed, which has an azide group attached to each Ge-atom. X-ray analysis reveals that the nine nitrogen atoms of the azide groups are coplanar with the trigonal planar Ge₃N moiety (crystallographic symmetry: 3/m). The reaction of 1 with 3 is very surprising: the pyridine in the product Me₂Si(NtBu)₂Ge(C₅H₄N)? N(H)Ge(tBu)(NtBu)₂SiMe₂ ( 7 ) is bonded via an α-carbon atom while the remaining hydrogen has added to the nitride-nitrogen. 6 crystallizes in the monoclinic system space group C2/m, a = 24.306(9), b = 10.933(6), c = 19.420(9) Å, β = 91.81(2)° and Z = 4. 7 crystallizes in the hexagonal system space group P6₃/m with a = b = 16.73(1), c = 11.006(8) Å, γ = 120° and Z = 2, and 8 crystallizes in the monoclinic system space group P2₁/n, a = 11.341(6), b = 26.086(9), c = 13.244(7) Å, β = 98. I2(2)° mit Z = 4.     

Supramolecular Complexes Based on [M(CN)8]4– (M = Mo,W) and Aliphatic Amine CuII Tectons

Three heterometallic supramolecular complexes [Cu₂(pn)₄(Mo(CN)₈)·4H₂O] (pn = diaminopropane) ( 1 ), [Cu₂(pn)₄(W(CN)₈)·4H₂O] ( 2 ) and [Cu₂(1,2‐pn)₄(H₂O) (W(CN)₈)·3H₂O] ( 3 ) have been synthesized and structurally characterized by single‐crystal X‐ray diffraction studies. Complexes 1 – 3 exhibit three different networks. In 1 , the copper(II) ion is pentacoordinate with a distorted square‐pyramidal arrangement and the network is formed by the incorporation of coordinative linkage between the μ₂ bridge of [Mo(CN)₈]^4– and copper(II) ions and hydrogen‐bonding interactions. In 2 , the copper(II) ion exhibits a distorted square‐pyramidal arrangement and the network is formed by the hydrogen bonded trinuclear complexesof [Cu₂(pn)₂(W(CN)₈)]. In 3 , the copper(II) ions show twodifferent distorted octahedral arrangements. The network structure of 3 is formed by the hydrogen‐bonded complex chains of [Cu₂(1,2‐pn)₂(W(CN)₈)].     

Spatiotemporal Studies of the One-Dimensional Coordination Polymer [Fe(ebtz)2(C2H5CN)2](BF4)2: Tug of War between the Nitrile Reorientation Versus Crystal Lattice as a Tool for Tuning the Spin Crossover Properties**

Reaction of 1,2-di(tetrazol-2-yl)ethane (ebtz) with Fe(BF₄)₂⋅6 H₂O in different nitriles yields one-dimensional coordination polymers [Fe(ebtz)₂(RCN)₂](BF₄)₂⋅nRCN (n=2 for R=CH₃ ( 1 ) and n=0 for R=C₂H₅ ( 2 ) C₃H₇ ( 3 ), C₃H₅ ( 4 ), CH₂Cl ( 5 )) exhibiting spin crossover (SCO). SCO in 1 and 3 – 5 is complete and occurs above 160 K. In 2 , it is shifted to lower temperatures and is accompanied by wide hysteresis (T_1/2^↓=78 K, T_1/2^↑=123 K) and proceeds extremely slowly. Isothermal (80 K) time-resolved single-crystal X-ray diffraction studies revealed a complex nature for the HS→LS transition in 2 . An initial, slow stage is associated with shrinkage of polymeric chains and with reduction of volume at 77 % (in relation to the difference between cell volumes V_HS−V_LS) whereas only 16 % of iron(II) ions change spin state. In the second stage, an abrupt SCO occurs, associated with breathing of the crystal lattice along the direction of the Fe–nitrile bonds, while the nitriles reorient. HS→LS switching triggered by light (808 nm) reveals the coupling of spin state and nitrile orientation. The importance of this coupling was confirmed by studies of [Fe(ebtz)₂(C₂H₅CN/C₃H₇CN)₂](BF₄)₂ mixed crystals ( 2 a , 2 b ), showing a shift of T_1/2 to higher values and narrowing of the hysteresis loop concomitant with an increase of the fraction of butyronitrile. This increase reduces the capability of nitrile molecules to reorient. Density functional theory (DFT) studies of models of 1 – 5 suggest a particular possibility of 2 to adopt a low (140–145°) value of its Fe-N-C(propionitrile) angle.     

Diboron Bonds Between BX3 (X=H,F, CH3) and BYZ2 (Y=H,F; Z=CO,N2, CNH)

The ability of B atoms on two different molecules to engage with one another in a noncovalent diboron bond is studied by ab initio calculations. Due to electron donation from its substituents, the trivalent B atom of BYZ₂ (Z=CO, N₂, and CNH; Y=H and F) has the ability to in turn donate charge to the B of a BX₃ molecule (X=H, F, and CH₃), thus forming a B⋅⋅⋅B diboron bond. These bonds are of two different strengths and character. BH(CO)₂ and BH(CNH)₂, and their fluorosubstituted analogues BF(CO)₂ and BF(CNH)₂, engage in a typical noncovalent bond with B(CH₃)₃ and BF₃, with interaction energies in the 3–8 kcal/mol range. Certain other combinations result in a much stronger diboron bond, in the 26–44 kcal/mol range, and with a high degree of covalent character. Bonds of this type occur when BH₃ is added to BH(CO)₂, BH(CNH)₂, BH(N₂)₂, and BF(CO)₂, or in the complexes of BH(N₂)₂ with B(CH₃)₃ and BF₃. The weaker noncovalent bonds are held together by roughly equal electrostatic and dispersion components, complemented by smaller polarization energy, while polarization is primarily responsible for the stronger ones.     

Synthese und Koordinationsverhalten von (Ph3SnO)3As. Die Kristallstrukturen von (Ph3SnO)3As und [{(Ph3SnO)3As}Fe(CO)4]

Synthesis and Coordination Behaviour of (Ph₃SnO)₃As. The Crystal Structures of (Ph₃SnO)₃As and [{(Ph₃SnO)₃As}Fe(CO)₄] (Ph₃SnO)₃As ( 1 ) was obtained from the reaction of Ph₃SnOH with As₂O₃ in a dichloromethane/water mixture as solvent. Upon recrystallization from DMF 1 forms orthorhombic crystals, space group P2₁2₁2₁, with a = 977.3(2), b = 1903.5(3) and c = 2600.9(5) pm (at 220 K). In 1 the As atom is bound to three OSnPh₃ groups with As–O distances of 171.9(3)–174.9(3) pm. Reaction of 1 with Fe₂(CO)₉ gives [{(Ph₃SnO)₃As}Fe(CO)₄] ( 2 ). 2 crystallizes monoclinic, space group P2₁/n with a = 2242.3(5), b = 1112.6(2), c = 2353.0(5) pm and β = 111,46(2)° (at 220 K). In 2 the iron atom exhibits a trigonal bipyramidal coordination with the (Ph₃SnO)₃As ligand in an axial position. The Fe–As bond length is 230.5(1) pm.     

Proton‐Assisted Hydrogen Activation on Polyhedral Cations

The treatment of [1,1‐(PR₃)₂‐3‐(Py)‐closo‐1,2‐RhSB₉H₈] (PR₃=PMe₃ ( 2 ) or PPh₃ and PMe₃ ( 3 ); Py=pyridine) with triflic acid (TfOH) affords [1,3‐μ‐(H)‐1,1‐(PR₃)₂‐3‐(Py)‐1,2‐RhSB₉H₈]⁺ (PR₃=PMe₃ ( 4 ) or PMe₃ and PPh₃ ( 5 )). These products result from the protonation of the 11‐vertex closo‐cages along the Rh(1)? B(3) edge. These unusual cationic rhodathiaboranes are stable in solution and in the solid state and they have been fully characterized by multinuclear NMR spectroscopy. In addition, compound 5 was characterized by single‐crystal X‐ray diffraction. One remarkable feature in these structures is the presence of three {Rh(PPh₃)(PMe₃)}‐to‐{ηⁿ‐SB₉H₈(Py)} (n=4 or 5) conformers in the unit cell, thus giving an uncommon case of conformational isomerism. [1,1‐(PPh₃)₂‐3‐(Py)‐closo‐1,2‐RhSB₉H₈] ( 1 ), that is, the bis‐PPh₃‐ligated analogue of compounds 2 and 3 , is also protonated by TfOH, but, in marked contrast, the resulting cation, [1,3‐μ‐(H)‐1,1‐(PPh₃)₂‐3‐(Py)‐1,2‐RhSB₉H₈]⁺ ( 6 ), is attacked by a triflate anion with the release of a PPh₃ ligand and the formation of [8,8‐(OTf)(PPh₃)‐9‐(Py)‐nido‐8,7‐RhSB₉H₉] ( 9 ). The result is an equilibrium that involves cationic species 6 , neutral OTf‐ligated compound 9 , and [HPPh₃]⁺, which is formed upon protonation of the released PPh₃ ligand. The resulting ionic system reacts readily with H₂ to give cationic species [8,8,8‐(H)(PPh₃)₂‐9‐(Py)‐nido‐8,7‐RhSB₉H₉]⁺ ( 7 ). This reactivity is markedly higher than that previously found for compound 1 and it introduces a new example of proton‐assisted H₂ activation that occurs on a polyhedral boron‐containing compound.     

Neue Oxonium-Bromochalkogenate(IV) — Darstellung,Struktur und Eigenschaften von [H3O][TeBr5] · 3C4H8O2 und [H3O]2[SeBr6]

New Oxonium Bromochalcogenates(IV) — Synthesis, Structure, and Properties of [H₃O][TeBr₅] · 3 C₄H₈O₂ and [H₃O]₂[SeBr₆] Dark red crystals of the composition [H₃O][TeBr₅] · 3 C₄H₈O₂ ( 1 ) were isolated from a saturated solution of TeBr₄ in 1,4-dioxane containing a small amount of water. In this compound (space group P2₁/m, a = 8.922(4) Å, b = 13.204(7) Å, c = 9.853(5) Å, β = 91.82(4)° at 150 K) a square pyramidal [TeBr₅]^? anion has been isolated for the first time. The coordination sphere of the anion is completed to a distorted octahedron by weak interaction with a dioxane molecule of the cationic system. The [H₃O]⁺ cations are connected to chains by dioxane molecules. At room temperature the compound is stable only in its mother liquor. Crystalline [H₃O]₂[SeBr₆] ( 2 ) (space group Fm3m, a = 10.421(1) Å at 170 K) is a bromoselenous acid of high symmetry. The [H₃O]⁺ ion is only weakly coordinated by Br atoms of the anion. The anions are isolated octahedral [SeBr₆]^2? units. The structure is isotypic to the K₂[PtCl₆] structure. Despite being a halogenochalcogen(IV) acid, 2 exhibits a remarkable thermal stability. Both oxonium compounds were characterized by single-crystal X-ray structure analyses. Vibrational spectra of 2 are reported.     

Reaktionen von π-Organokomplexen des Nickels mit tertiären Phosphanen

Reactions of π-Organonickel Complexes with Tertiary Phosphanes In a hexane solution Ni(C₅H₅)₂ reacts with PBu₃ or Ph₂PBu forming the nickel(O) complexes Ni(PBu3)₄ or Ni(Ph₂PBu)₄ (A). Under the same conditions only one cyclopentadienyl ligand is substituted by PhPBu₂ and the nickel(I) compound (C₅H₅)Ni (PhPBu₂)₂ (B) is obtained. Products of the reactions between B and α,α′-dipyridyl, hydrogen chlorid in ether, or Ni(PhPBu₂),Cl₂ are Ni(dipy)₂, [PhPHBu₂]₂[NiCl₄], or (C₅H₅) Ni(PhPBu₂)₂Cl. By the reaction with HgCl₂ a cyclopentadienyl compound of an unknown structur is formed. The compound Ni(PhPBu₂)₄ which is analogous to A is synthesized by the reduction of bis(acety1acetonato)-nickel with Et₂AlOEt in the presence of PhPBu₂ or by the reaction of bis (cyclooctadiene-1,5)-nickel with PhPBu₂.     

Pyrazine-2,3-dicarboxylate-bridged polymeric and dinuclear complexes involving decameric water clusters

Two copper(II) complexes of pyrazine-2,3-dicarboxylate (H₂pzdc) with 2-aminopyridine (apy), {(Hapy)₂[Cu(μ-pzdc)₂]} _n (1) and 1,10-phenanthroline (phen), [Cu₂(μ-pzdc)(phen)₄][N(CN)₂]₂?·9H₂O (2) have been synthesized and structurally characterized. Complex 1 consists of a pyrazine-2,3-dicarboxylate bridging across a double chain, while 2 exists as a dinuclear complex in which two Cu(II) ions are bridged by pzdc via different coordination modes. One Cu(II) ion in the binuclear complex is a distorted octahedron, while the other Cu(II) is a distorted trigonal bipyramid. A chair-like decameric water cluster composed of two pentamers and a shared-edge tetramer is detected, which further associate into a 1-D tape with dicyanamide anions by hydrogen bonds.