Synthesis and Crystal Structure of a Polymeric Heteronuclear Complex of Cadmium(II) and Silver(I)

A polymeric complex of Cd(II) and Ag(I) bridged by thiocyanate and ethylenediamine, [Cd(en)_1.5Ag(SCN)₃], has been prepared and its structure determined by X-ray diffraction methods. The complex crystallizes in space group P2₁/n with a =7.456(1), b =9.915(2), c =19.822(2)Å, β =98.94(1)°. The Cd(II) atom is octahedrally coordinated by three SCN^- anions and two en molecules, while the Ag(I) atom is tetrahedraly coordinated by four SCN^- anions. Both SCN^- anions and en molecules act as bridging ligands and link Ag(I) and Cd(II) atoms to form a three-dimensional polymeric structure. The distance between Ag(I) and the atom S of a 1,1,3-µ3-SCN^- anion is much longer than that between Ag(I) and the atom S of a 1,3-µ-SCN^- anion. The short Ag-Ag distance of 3.133 Å and small Ag-S-Ag angle of 70.92° strongly suggests the existence of an Ag-Ag bonding interaction in the complex.     

A Structurally Characterized Cobalt(I) σ‐Alkane Complex

A cobalt σ‐alkane complex, [Co(Cy₂P(CH₂)₄PCy₂)(norbornane)][BAr^F₄], was synthesized by a single‐crystal to single‐crystal solid/gas hydrogenation from a norbornadiene precursor, and its structure was determined by X‐ray crystallography. Magnetic data show this complex to be a triplet. Periodic DFT and electronic structure analyses revealed weak C?H→Co σ‐interactions, augmented by dispersive stabilization between the alkane ligand and the anion microenvironment. The calculations are most consistent with a η¹:η¹‐alkane binding mode.     

Zur Reaktion der Alkin‐Kupfer(I)‐Komplexe [CuCl(S‐Alkin)] und [Cu2Br2(S‐Alkin)(dms)] (S‐Alkin = 3,3,6,6‐Tetramethyl‐1‐thia‐4‐cycloheptin,dms = Dimethylsulfid) mit den Lithiumorganylen Phenyllithium und Fluorenyllithium

Organometallic Compounds of Copper. XX On the Reaction of the Alkyne Copper(I) Complexes [CuCl(S‐Alkyne)] and [Cu₂Br₂(S‐Alkyne)(dms)] (S‐Alkyne = 3,3,6,6‐Tetramethyl‐1‐thiacyclohept‐4‐yne; dms = Dimethylsulfide) with the Lithiumorganyls Phenyllithium und Fluorenyllithium The alkyne copper(I) bromide complex [Cu₂Br₂(S‐Alkyne)(dms)] ( 3 b ) (S‐Alkyne = 3,3,6,6‐tetramethyl‐1‐thiacyclohept‐4‐yne; dms = dimethylsulfide) reacts with phenyllithium to form a tetranuclear copper(I) complex of the composition [Cu₄(C₆H₅)₂(S‐Alkenyl)₂] ( 7 ) in low yield (4%). The reaction of the alkyne copper(I) chloride complex [CuCl(S‐Alkyne)] ( 2 a ) with fluorenyllithium in tetrahydrofuran (thf) affords a lithium cuprate of the composition [Li(thf)₄]⁺ [Cu₂(fluorenyl)₃(S‐Alkyne)₂]^– ( 8 ) (yield 32%). The structures of both new complexes 7 and 8 were determined by X–ray diffraction.     

Trichloropalladate(II) Complexes with Pyridine Ligands – Molecular Structure and Conformational Analysis of [K(18C6)][PdCl3(py)]

[K(18C6)]₂[Pd₂Cl₆] ( 1 ) (18C6 = 18‐crown‐6) was found to react with pyridines in a strictly stoichiometric ratio 1 : 2 in methylene chloride or nitromethane to yield trichloropalladate(II) complexes [K(18C6)][PdCl₃(py*)] (py* = py, 2a ; 4‐Bnpy, 2b ; 4‐tBupy, 2c ; Bn = benzyl; tBu = tert‐butyl). The reaction of 1 with pyrimidine (pyrm) in a 1 : 1 ratio led to the formation of the pyrimidine‐bridged bis(trichloropalladate) complex [K(18C6)]₂[(PdCl₃)₂(μ‐pyrm)] ( 3 ). The identities of the complexes were confirmed by means of NMR spectroscopy (¹H, ¹³C) and microanalysis. The X‐ray structure analysis of 2a reveals square‐planar coordination of the Pd atom in the [PdCl₃(py)]^? anion. The pyridine plane forms with the complex plane an angle of 55.8(2)°. In the [K(18C6)]⁺ cation the K⁺ lies outside the mean plane of the crown ether (defined by the 6 O atoms) by 0.816(1) Å. There are tight K···Cl contacts between the cation and the anion (K···Cl1 3.340(2) Å, K···Cl2 3.166(2) Å). To gain an insight into the conformation of the [PdCl₃(py)]^? anion, DFT calculations were performed showing that the equilibrium structure ( 6eq ) has an angle between the pyridine ligand and the complex plane of 35.3°. Rotation of the pyridine ligand around the Pd–N vector exhibited two transition states where the pyridine ligand lies either in the complex plane ( 6TS _pla, 0.87 kcal/mol above 6eq ) or is perpendicular to it ( 6TS _per, 3.76 kcal/mol above 6eq ). Based on an energy decomposition analysis the conformation of the anion is discussed in terms of repulsive steric interactions and of stabilizing σ and π orbital interactions between the PdCl₃^? moiety and the pyridine ligand.     

Synthesis Characterization,X‐ray Structures,and Solution Studies of Dinuclear Zinc(II) Complexes of Acyclic Schiff Base Ligands

Dizinc(II) complexes of two acyclic Schiff‐base ligands L1 ^– and L2 ^– were synthesized by Schiff base condensation of 2‐[3‐(2‐formylphenoxy)‐2‐hydroxypropoxy]benzaldehyde ( PL ) with 1,2‐diaminopropane and 1,2‐diaminoethane, respectively, in the presence of zinc(II) salts. The isolation of a selection of 2:1 (metal:ligand) complexes of zinc(II) was carried out and conductance measurements, IR, UV/Vis absorption, and fluorescence emission spectroscopy, as well as X‐ray diffraction were employed to probe the nature of the respective complexes in both solid and solution states. The molecular structure of [Zn₂ L1 (NO₃)₃] ( 1 ) complex consists of two six‐coordinate atoms, which are bridged by the deprotonated hydroxy group and one 1,3‐bridging nitrate anion. The structure of [Zn₂ L2 (NO₃)(H₂O)₂](NO₃)₂ · CH₃OH ( 3 ) consists of a dizinc cation and two nitrate anions as counterions. In compound 3 , each zinc atom is bound to water instead of a terminal nitrate anion in a distorted octahedral arrangement. The intermetallic separation distance of Zn ··· Zn in 3 (3.376 Å) is slightly smaller than 1 (3.403 Å) and is similar to that found in zinc phosphotriesterase (3.5 Å). The π–π interactions between the benzene rings of adjacent molecules in 3 are stronger than in 1 .     

Stabilization of Discrete [Cu(C2O4)2(H2O)2]2— Dianions in the Solid State by an Extensive Hydrogen Bonded Network

The dominant species in aqueous copper(II) solutions containing a high concentration of oxalate (ox) is trans‐[Cu(ox)₂(H₂O)₂]^2—, yet the ability of the oxalate anion to bridge metal ions means that very few examples of this isolated anion are seen in solid state structures. The structure of [pipH₂]²⁺[Cu(ox)₂(H₂O)₂]^2— · 2H₂O (pip = piperazine) ( 1 ) comprises discrete ions held in a complex 3‐dimensional hydrogen bonded network.     

Crystal Structure and IR Spectrum of Diaqua(o‐phenanthroline) bis(saccharinato)lead(II)

The crystal structure of [Pb(sac)₂ophen(H₂O)₂] (sac = saccharinate anion; ophen = 1,10‐phenanthroline) has been solved by single X‐ray diffractometry. It crystallizes in the monoclinic space group C2/c with Z = 4. The Pb^II atom presents the coordination number eight with unusual coordination of the ligand atoms between square‐antiprism and dodecahedron. The saccharinate anion acts as a bidentate ligand. The i. r. spectrum of the complex has been analyzed in detail and assigned on the basis of the structural peculiarities.     

Opening up the Valence Shell: A T‐Shaped Iron(I) Metalloradical and Its Potential for Atom Abstraction

A thermally stable, T‐shaped, d⁷ high‐spin iron(I) complex was obtained by reduction of a PNP‐supported ferrous chloride. Paramagnetic NMR spectroscopy combined with DFT modeling was used to analyze the electronic structure of the coordinatively highly unsaturated complex. The metalloradical character of the compound was demonstrated by the formation of a benzophenone ketyl radical complex upon addition of benzophenone. Furthermore, the compound displays a rich chemistry as an oxygen‐atom abstractor from epoxides, yielding a dinuclear, diferrous [Fe₂O] complex.     

Multivalent Complex Salts of Copper: Synthesis and X‐Ray Structural Analysis of [CuII(en)3][CuI4{(NNNPh)2C6H4}3] (en = ethylendiamine), an anionic Tris‐1,3‐bis(phenyltriazenide)benzene Complex of Tetrakis‐Copper(I)

An ethanolic solution of CuCl / ethylendiamine reacts with 1.3‐bis‐ (phenyltriazene)benzene in THF leading to the deprotonation of the bis triazene ligand to give orange crystals of [Cu^II(en)₃][Cu^I₄{(NNN‐Ph)₂C₆H₄}₃], an example of a rare complex salt of copper with mixed valence states. In the anion complex [Cu^I₄{(NNNPh)₂C₆H₄}₃]^2? the copper(I) ions are disposed linearly as single, bridged pairs in the two extremes of an axis, each of them presenting a trigonal bipyramidal alike coordination arrangement.     

Synthesis of Zwitterionic Cobaltocenium Borate and Borata‐alkene Derivatives from a Borole‐Radical Anion

Chemical single‐electron reduction of 1‐mesityl‐2,3,4,5‐tetraphenylborole ( 3 ) gave a stable radical anion [CoCp*₂][ 3 ] as shown in earlier investigations. Herein, we present the reaction of [CoCp*₂][ 3 ] with the 2,2,6,6‐tetramethylpiperidine‐N‐oxyl radical (TEMPO), a common radical trap. Instead of radical recombination, the reaction proceeds through a redox pathway involving oxidation of the borole radical anion combined with reduction of TEMPO. This electron‐transfer process is accompanied by a deprotonation reaction of the cobaltocenium counterion by the base TEMPO^? to give TEMPO‐H and a neutral cobalt(I) fulvene complex ( 7 ). The latter was not observed directly during the reaction, because it instantaneously reacts as a nucleophile attacking at the boron center of the in situ generated borole 3 to give the borate 6 . However, 7 was synthesized independently by deprotonation of [CoCp*₂][PF₆]. In addition, the obtained zwitterionic cobaltocenium borate 6 undergoes a photolytic rearrangement to form the borata‐alkene derivative 9 that thermally transforms to the chiral cobaltocenium borate 12 . Our investigations are based on spectroscopic evidence, X‐ray crystallography, elemental analysis, as well as DFT calculations.     

Structure and Magnetic Properties of Mononuclear Copper(II) Complexes with 2,2‐Bipyrimidine, 2,3‐Bis(2‐pyridyl)pyrazine,and 4‐Terpyridone Based Ligands

Four new complexes of [Cu(bpm)(ox)(H₂O)] ( 1 ), [Cu(tpd)(dca)(H₂O)] ( 2 ), [Cu(bppz)(N₃)₂] ( 3 ), and [Cu(bpm)₂(μ_1,3‐N₃)(N₃)] ( 4 ) (bpm = 2,2′‐bipyrimidine, bppz = 2,3‐bis(2‐pyridyl)pyrazine, tpd = 4‐terpyridone, dca = dicyanamide, ox = oxalate) have been prepared and characterized by X‐ray single‐crystal analysis and variable‐temperature magnetic measurements. Compounds 1–4 are essentially mononuclear Cu(II) complexes. However, in complex 1 , Cu(II) it was found that intermolecular hydrogen bonding through between H₂O and ox formed 1‐D chain structure. In complex 2 it was found that the hydrogen bonding between H₂O and tpd of the next molecule led to for a binuclear Cu(II) complex. In complex 3 , two nitrogen atoms, one of the pyridyl group of bppz and one of N₃^? ligands, are weakly coordinated to neighbor Cu(II) ion thus leading to formation of a 1‐D chain structure. In complex 4 , one nitrogen atom of terminated N₃^? is weakly coordinated to the neighbor Cu(II) site to form a 1‐D polymeric structure. The magnetic susceptibility measurements indicate that complex 1 and 4 exhibit a weak antiferromagnetic interaction whereas a ferromagnetic coupling has been established for complexes 2 and 3 .     

ESI‐MS studies of palladium (II) complexes with 1‐(p‐toluenesulfonyl)cytosine/cytosinato ligands

The mononuclear complex Pd(1‐TosC‐N3)₂Cl₂ (2) containing 1‐(p‐toluenesulfonyl)cytosine (1) as a ligand, as well as dinuclear complexes Pd₂(1‐TosC^?‐N3,N4)₄ (3) and Pd₂(1‐TosC^?‐N3,N4)₂DMSO₂Cl₂ (4) containing the ligand anion (1‐TosC^?), was mass analyzed by electrospray ionization ion trap MS/MS and high resolution MS. Complexes 3 and 4 were obtained by recrystallization of 2 from DMF and DMSO, respectively. The behavior of complex 2 in different solutions was monitored by electrospray ionization mass spectrometry (ESI‐MS). Under the applied ESI‐MS conditions, complex 2 in methanol reorganized itself dominantly as new complex 3 and the solvent did not coordinate the formed species. In H₂O/DMSO, CH₃CN/DMSO and CH₃OH/DMSO solutions, complex 2 formed several new species with solvent molecules involved in their structure, e.g. complex 4 was formed as the major product. The newly formed species were also examined by LC‐MS‐DAD, confirming the solvent induced reorganization and the solution instability of complex 2. Copyright © 2009 John Wiley & Sons, Ltd.     

Syntheses,Structures, and Properties of the Complexes [Ag(N∧S)n](X), N∧S = 1‐Methyl‐2‐(alkylthiomethyl)‐1H‐benzimidazoles,X = PF6 (n = 2) or PO2F2 (n = 1)

The complexes [Ag(η²‐N∧S)₂](PF₆), N∧S = 1‐methyl‐2‐(methylthiomethyl)‐1H‐benzimidazole, mmb (complex 1 ) or 1‐methyl‐2‐(tert‐butylthiomethyl)‐1H‐benzimidazole, mtb (complex 2 ), and [Ag(μ,η²‐mmb)(μ,η²‐O₂PF₂)] (complex 3 ) were synthesized and characterized by X‐ray crystallography. Long Ag–S (ca. 2.70 Å) and shorter Ag–N bonds (ca. 2.23 Å) are part of characteristically distorted tetrahedral coordination arrangements at the silver(I) ions in 1 and 2 . Unexpectedly, the comparison with the copper analogue [Cu(η²‐mmb)₂](PF₆) reveals a more tetrahedral and less linear coordination arrangement for the corresponding silver species. Compound 3 as obtained by hydrolysis of the PF₆ ion or by the use of AgPO₂F₂ exhibits bridging mmb and η²‐difluorophosphate ligands in a chain‐type structure.     

Mimicking Class I b Mn2‐Ribonucleotide Reductase: A MnII2 Complex and Its Reaction with Superoxide

A fascinating discovery in the chemistry of ribonucleotide reductases (RNRs) has been the identification of a dimanganese (Mn₂) active site in class I b RNRs that requires superoxide anion (O₂^.?), rather than dioxygen (O₂), to access a high‐valent Mn₂ oxidant. Complex 1 ([Mn₂(O₂CCH₃)(N‐Et‐HPTB)](ClO₄)₂, N‐Et‐HPTB=N,N,N′,N′‐tetrakis(2‐(1‐ethylbenzimidazolyl))‐2‐hydroxy‐1,3‐diaminopropane) was synthesised in high yield (90 %). 1 was reacted with O₂^.? at ?40 °C resulting in the formation of a metastable species ( 2 ). 2 displayed electronic absorption features (λ_max=460, 610 nm) typical of a Mn‐peroxide species and a 29‐line EPR signal typical of a Mn^IIMn^III entity. Mn K‐edge X‐ray absorption near‐edge spectroscopy (XANES) suggested a formal oxidation state change of Mn^II₂ in 1 to Mn^IIMn^III for 2 . Electrospray ionisation mass spectrometry (ESI‐MS) suggested 2 to be a Mn^IIMn^III‐peroxide complex. 2 was capable of oxidizing ferrocene and weak O?H bonds upon activation with proton donors. Our findings provide support for the postulated mechanism of O₂^.? activation at class I b Mn₂ RNRs.     

Coordination Chemistry of Acrylamide: 1. Cobalt(II) Chloride Complexes with Acrylamide – Synthesis and Crystal Structures

The molecular structures of blue dichloro‐tetrakis(acrylamide) cobalt(II), [Co{O‐OC(NH₂)CH=CH₂}₄Cl₂] ( 1 ) and pink hexakis(acrylamide)cobalt(II) tetrachlorocobaltate(II), [Co{O‐OC‐(NH₂)CH=CH₂}₆][CoCl₄] ( 2 ), characterized by single X‐ray diffraction, IR spectroscopy and elemental analyses, are described. The coordination of Co^II in 1 involves a tetragonally distorted octahedral structure with four O‐donor atoms of acrylamide in the equatorial positions and two chloride ions in the apical positions. The second complex 2 in ionic form contains Co^II cations surrounded by an octahedral array of O‐coordinated acrylamide ligands, accompanied by a [CoCl₄]^2? anion.     

A Novel Organosulfonate Cadmium(II) Complex with Graphite‐like 2D Layer Linked by Hydrogen Bonds

A novel mixed‐ligand complex, [Cd(im)₆][Cd(im)₃(H₂O)₃]₂(ans)₆ · 8H₂O ( 1 ), was obtained from the reaction ofCd(OAc)₂ · 2H₂O, imidazole (im) and sodium 4‐aminonaphthalene‐1‐sulfonate tetrahydrate (Na‐ans) in a mixed solvent at 25 °C. The complex was characterized by elemental analysis, IR spectroscopy, and X‐ray single crystal diffraction. There are two kinds of cations constructed by Cd^II atoms with a octahedral coordination arrangement in 1 . The Cd^II atom is bonded by six nitrogen atoms from six im ligands in the first cation, and the second central Cd^II atom is bonded by three nitrogen atoms of im molecules and three oxygen atoms belonging to water molecules. The ans anion acts as a counterion to balance the charge, and the adjacent anions are reversed but non‐parallel interlinked by N–H ··· O(S) hydrogen bonds into graphite‐like 2D sheet viewed from the c axis. The anionic channels along the [110] direction are filled with the cations, and the two kinds of cations are alternatingly arranged in the channels. The hydrogen‐bonding interactions together with the ionic bonds stabilize the crystal structure. The thermostability of the complex was investigated by TG and DSC.     

Crystal structure of the complex of 1,10-diaza-18-crown-6 with the potassium salt of N-(Diisopropoxyphosphoryl)thiobenzamide

The crystal structure of the complex of 1,10-diaza-18-crown-6 with the potassium salt of N-(diiso-propoxyphosphoryl)thiobenzamide (I) was investigated by the XRD method (CAD-4 automatic diffractometer, γCuK_α; space group P2₁/n, a = 12.218(2), b = 16.976(3), c = 15.706(2) å, Β = 93.72(1)?, Z = 4. The structure was solved by direct methods and refined by the full-matrix least-squares procedure anisotropically to R = 0.058 for all 3330 correct independent reflections. Complex I is a guest-host type complex (composition 1:1:1), whose individual molecule consists of two different hosts (azacrown ether and organophosphorus anion) and their common guest — heptacoordinated cation K⁺. The coordination sphere of K⁺ involves one phosphoryl oxygen atom of the anion of complex I. The azacrown ether atoms and the K⁺ cation in the crystal structure of complex I are disordered at two positions.     

Stabilization of an Intramolecularly Coordinated Stannylidenium Cation

The treatment of trans‐{[2, 6‐(Me₂NCH₂)₂C₆H₃]SnI}₂PtI₂ with Na(pyt) (pyt = 2‐mercaptopyridine) yielded the unprecedented complex {{[2, 6‐(Me₂NCH₂)₂C₆H₃]Sn}Pt(μ‐pyt)₂I} ( 1 ), where a Sn←N coordinated stannylidenium (LSn^II)⁺ fragment donates a to a [Pt^II(pyt)₂I]^– anion. Compound 1 was characterized by NMR spectroscopy and molecular structure was determined by X‐ray diffraction analysis. The bonding situation in 1 was analyzed by DFT studies.     

(PPh4)2[Cl2Re(N3S2)(μ‐NSN)(μ‐N≡ReCl3)]2 – ein Rhenium(VII)‐Komplex mit einer Nitrido‐, einer Dinitridosulfato(II)‐ und einer Rhena‐3,5‐dithia‐2,4,6‐triazino‐Funktion

(PPh₄)₂[Cl₂Re(N₃S₂)(μ‐NSN)(μ‐N≡ReCl₃)]₂ – a Rhenium(VII) Complex with a Nitrido, a Dinitridosulfato(II), and a Rhena‐3,5‐dithia‐2,4,6‐triazino Function The title compound has been prepared from PPh₄[Re^VIICl₄(NSCl)₂] with N(SiMe₃)₃ in dichloromethane solution to give red‐brown single crystals, which were suitable for a crystal structure determination. As a by‐product PPh₄[ReNCl₄] is formed. (PPh₄)₂[Cl₂Re^VII(N₃S₂)(μ‐NSN)(μ‐N≡Re^VIICl₃)]₂ ( 1 ): Space group P2₁/c, Z = 2, lattice dimensions at –80 °C: a = 1280.8(2), b = 1017.5(1), c = 2467.8(3) pm, β = 95.04(1)°, R = 0.049. The complex anion of 1 consists of a planar ReN₃S₂‐heterocycle which is connected with the second rhenium atom by a μ‐nitrido bridge as well as by a μ‐dinitridosulfato(II) ligand to form a planar Re₂(N)(NSN) six‐membered heterocycle. This [Cl₂Re(N₃S₂)(μ‐NSN)(μ‐N≡ReCl₃)]^– unit dimerizes via one of the N‐atoms of the (NSN)^4– ligand to give a centrosymmetric Re₂N₂ four‐membered ring.     

Synthesis and Structural Study of Copper(I) or Silver(I) Complexes of 2,11‐Dithia‐4,5,6,7,8,9‐Hexahydro[3.3]paracyclophanes

The complexes of 2,11‐dithia‐4,5,6,7,8,9‐hexahydro[3.3]paracyclophane (dthhpcp) with Cu(I), i.e. [Cu₂I₂(dthhpcp)₂]·2H₂O 1 , or with Ag(I), i.e. [Ag(dthhpcp)(NO₃)]thf 2 and [Ag(dthpcp)(CF₃COO)] 3 , were prepared for structural study by single‐crystal X‐ray diffraction analysis. For these three complexes, dthhpcp serves as a bridging group in the polymeric structure through bridging sulfur atoms via metal, while the bonding of anion with the second metal atom forms the multi‐diminished structures. Complex 1 is a novel two‐dimensional coordination polymer composed of Cu₆ motifs, in which Cu₂I₂ formed a square planar unit to link the dthhpcp molecule. The two oxygen atoms of the nitrate anion as a bridge for two Ag atoms in complex 2 provides a three‐dimensional channel framework of silver(I) with a tetrahydrofuran molecule as a guest inside the open cavities. In contrast, the analogous reaction with silver triflouroacetate gave a complex 3 , which is composed of infinite linear chains of‐Ag‐dthhpcp‐Ag‐dthhpcp‐ along the a axis. Unit cell data: complex 1 , orthorhombic system, space group P2(1)2(1)2(1), a = 19.2982(11) Å b = 16.5661(10) Å, c = 25.3006(15) Å, β = 90°, Z = 8; complex 2 , orthorhombic system, space group Pna2(1), a = 8.8595(6) Å, b = 12.6901(9) Å, c = 19.8449(14) Å, β = 90°, Z = 4; complex 3 , monoclinic system, space group P2(1)/n, a = 8.845(3) Å, b = 20.841(6) Å, c = 11.061(3) Å, β = 107.832(6)°, Z = 4.