Conversion of alkynes and nitriles into organo and organonitrogenated species at group VI and VII dinitrogen-binding metal centers. Synthesis of some vinylidene and alkynyl complexes of rhenium

Summary The reactions of phenylacetylene and other alkynes [HCCCH₂OH, HCC(CH₂)₂OH, HCCCH₂CMe ₂CH₂COCH₃, HCCSiMe ₃ andMeCCSiMe ₃], in the presence of acetonitrile or benzonitrile, with the following complexes have been investigated usually at room temperature:trans-[Mo(N₂)₂ L ₄] (L=PMe ₂ Ph),cis-[Mo(N₂)₂(PMePh ₂)₄],cis-[W(N₂)₂ L ₄],trans-[ReCl(N₂)L ₄],mer-[ReCl(N₂)(PPh ₃)L₃] {L=P(OMe)₃}, [ReCl₂(N₂COPh)L₃] and [(⁵-MeC₅H₄)Mn(CO)₂(NCMe)]. Cyclic trimerization was the main reaction detected for phenylacetylene (except for the Mn complex), although dimers, products of hydrogenation and species derived from alkyne/nitrile coupling were also formed in smaller amounts; for the Mo- or W-systems, the total yields were below ca. 40% relative to the metal, but the Re-systems exhibited a modest catalytic activity. The other alkynes underwent, also in low yields, mainly dimerization, cyclic or linear trimerization, apart from, to a smaller extent, coupling reactions with the nitriles or hydrogenation. The alkynyl complexes [ReCl(CCPh) {P(O) (OMe)₂}(PPh ₃)L₂] and [ReCl(CCPh) {P(O)(OMe)₂}(NCMe)₂ L] were prepared by reaction ofmer-[ReCl(N₂)(PPh ₃)L₃] withPhCCH, in the absence and in the presence of NCMe, respectively, whereas the benzonitrile/dinitrogen complex [ReCl(N₂)(CNPh)L₃] was obtained either by reaction of that N₂-complex with NCPh or by the reaction of [ReCl₂(N₂COPh)L₃] with NCPh in the presence of NaOMe. The vinylidene compoundtrans-[Re(CNMe)(C=CHPh)(dppe)₂][BF₄] (dppe=Ph ₂PCH₂CH₂PPh ₂) was formed by reaction oftrans-[ReCl(CNMe)(dppe)₂] withPhCCH, in the presence of Tl[BF₄], which did not lead to the formation of detectable amounts of any alkyne-derived organic product.

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Umsetzung von Alkinen und Nitrilen zu Organo- und Organostickstoff-Spezies an distickstoffbindende Metallzentren der VI. und VII. Gruppe. Synthese einiger Vinyliden-und Alkinyl-Komplexe des Rhenium

Zusammenfassung Die Reaktionen von Phenylacetylen und anderen Alkinen [HCCCH₂OH, HCC(CH₂)₂OH, HCCCH₂CMe₂CH₂COCH₃, HCCSiMe₃ und MeCCSiMe₃] in Gegenwart von Acetonitril oder Benzonitril mit den folgenden Komplexen wurde wie üblich bei Raumtemperatur untersucht:trans-[Mo(N₂)₂ L ₄] (L=PMePh),cis-[Mo(N₂)₂(PMePh ₂)₄],cis-[W(N₂)₂ L ₄],trans-[ReCl(N₂)L ₄],mer-[ReCl(N₂)(PPh ₃)L₃] {L=P(OMe)₃}, [ReCl₂(N₂COPh)L₃] und [(⁵-MeC₅H₄)-Mn(CO)₂(NCMe)]. Die Hauptreaktion für Phenylacetylen war stets die cyclische Trimerisierung (mit Ausnahme des Mn-Komplexes), obwohl auch Hydrogenierungsprodukte und Spezies aus einer Alkin/Nitril-Kupplung in kleineren Mengen aufgefunden wurden; für die Mo- oder W-Systeme waren die Ausbeuten unter etwa 40% relativ zum Metall, die Re-Systeme zeigten eine schwache katalytische Aktivität. Die anderen Alkine gingen (auch in niedrigen Ausbeuten) hauptsächlich Dimerisierung, cyclische oder lineare Trimerisierung neben (in noch geringerem Maßstab) Kupplungs-reaktionen mit den Nitrilen oder Hydrogenierung ein. Die Alkinylkomplexe [ReCl(CCPh)-{P(O)(OMe)₂}(PPh ₃)L₂] und [ReCl(CCPh) {P(O)(OMe)₂}(NCMe)₂ L] wurden aus der Reaktion vonmer-[ReCl(N₂)(PPh ₃)L₃] mitPhCCH sowohl in Abwesenheit als auch in Gegenwart von NCMe gebildet, wohingegen der Benzonitril/Distickstoff-Komplex [ReCl(N₂)(NCPh)L₃] entweder aus der Reaktion dieses N₂-Komplexes mit NCPh oder über die Reaktion von [ReCl₂(N₂COPh)L₃] mit NCPh in Gegenwart von NaOMe gebildet wurde. Die Vinylidenverbindungtrans-[Re(CNMe)(C=CHPh)(dppe)₂] [BF₄] (dppe=Ph ₂PCH₂CH₂PPh ₂) wurde in der Reaktion vontrans-[ReCl(CNMe)-(dppe)₂] mitPhCCH in der Gegenwart von Tl[BF₄] gebildet, wobei keine detektierbaren Mengen irgendeines von Alkin abgeleiteten organischen Produkts entstanden.

     

Crystal Structures of Two Monomeric Copper(II) Carboxylates with 2-Aminopyridine

The crystal structures of two monomeric copper(II) carboxylates with 2-aminopyridine have been determined by X-ray diffraction. The hexanoate complex crystallizes as its acetonitrile solvate [Cu(C₆H₁₁O₂)₂(C₅H₆N₂)₂ · CH₃CN] in the triclinic space group P-1 with a = 8.1020(6), b = 13.7106(9), c = 13.7673(9) Å, = 113.79(1), = 103.86(1), and = 94.38(4). The heptanoate compound shows an unsolvated structure [Cu(C₇H₁₃O₂)₂(C₅H₆N₂)₂] and also crystallizes in the triclinic space group P-1 with the following cell parameters: a = 8.4487(9), b = 12.238(1), c = 13.504(2) Å, = 87.034(9), = 77.489(9), and = 71.41(1)^°. Both compounds contain the CuO₄N₂ chromophore, with ligands arranged around the copper center in a cis mode. 2-Aminopyridine is coordinated through the endocyclic nitrogen atom. The ortho position of the amino group, with respect to the pyridine nitrogen atom, allows the formation of both, intra-and intermolecular hydrogen bonds.     

Photoredox Reactions Occurring in Methanolic Solutions of Iron(III) Azido Complexes with <Emphasis Type="Italic">N,N</Emphasis>′-Ethylenebis (salicylaldiminato) <Emphasis Type="Italic">Schiff</Emphasis> Base Derivatives

Summary. Photoredox reactions occurring in irradiated methanolic solutions of trans-[Fe(N ₂ O ₂ ) (CH₃OH)N₃], where N ₂ O ₂ ^2– are tetradentate open-chain N ₂ O ₂ -Schiff base N,N-ethylenebis(R-salicylaldiminato) or N,N-1-methylethylenebis(R-salicylaldiminato) ligands denoted as R-salen and R-sal(Me)en, respectively (R=H, 5-Cl, 5-Br, 4-OCH₃), have been investigated and their mechanism has been proposed. The complexes are redox stable in the dark. Ultraviolet and/or visible irradiation of methanolic solutions of the complexes induces photoreduction of Fe(III) to Fe(II). As an intermediate, CH₂OH radicals were identified by EPR spin trapping technique. The final product of the photooxidation coupled with the photoreduction of Fe(III) is formaldehyde. The efficiency of the photoredox processes is strongly wavelength dependent and influenced by the peripheral groups R of the tetradentate ligands. Differences between the course of photochemical changes induced by 254nm radiation and the other wavelengths of incident radiation is rationalized by involving azide anions photoreactivity in observed redox changes.     

Syntheses,Spectra, Thermal Studies and Crystal Structures of Vitamin B13 Complexes of Nickel(II) with N,N,N′,N′‐Tetramethylethylenediamine and 2,2‐Dimethylpropane‐1,3‐diamine

Two nickel(II) complexes of vitamin B13 (H₃Or) with N,N,N′,N′‐tetramethylethylenediamine (tmen) and 2,2‐dimethylpropane‐1,3‐diamine (dmpen) were synthesized and characterized by means of elemental and thermal analyses, magnetic susceptibility, and IR and UV/Vis spectroscopic studies. The crystal structures of mer‐[Ni(HOr)(H₂O)₂(tmen)] · H₂O ( 1 ) and [Ni(HOr)(dmpen)₂] ( 2 ) were determined by using single‐crystal X‐ray diffraction. In the complexes, which crystallize in the triclinic system (space group for 1 ) and the monoclinic system (space group P2₁/c for 2 ), the Ni^II ions exhibit a distorted octahedral coordination. Ni^II ions are chelated by the deprotonated nitrogen atom of the pyrimidine ring and the oxygen atom of the carboxylate group, the distorted octahedral coordination completed by one tmen and two aqua ligands for 1 or two dmpen ligands for 2 .     

1D and 2D Systems Derived from Polynuclear [ ML(N 3) 2] n ( M?=?Zn(II) or Cd(II) and L is 2-Picoline- N-oxide or 4-Methylpyrimidine)

Summary. Four new polynuclear complexes: [Zn(2picNO)(N₃)₂]_n, [Zn(4Mepym)(N₃)₂]_n, [Cd(2picNO)(N₃)₂]_n, and [Cd(4Mepym)(N₃)₂]_n (2picNO=2-picoline-N-oxide and 4Mepym=4-methylpyrimidine) have been synthesized and characterized by single-crystal X-ray diffraction. The structures of the zinc(II) complexes feature five-coordinate zinc atoms, (-1,1) azido bridges, monodentate organic ligands, and 1D chains. The cadmium(II) azide complexes contain distorted octahedral metal atoms linked by alternate di-(-1,1) and di-(-1,3) azido bridges in cis arrangement and these chains are connected by 2picNO bridges giving a honeycomb 2D framework or by 4Mepym bridges forming extended 2D network structure.     

Thermal analysis of thione compounds

The thermal behavior of thiourea (Tu), N-methylthiourea (MeTu), N, N-dimethylthiourea (Me₂Tu) and N, N, N, N-tetramethylthiourea (Me₄Tu) was investigated by means of conventional thermal analysis in O₂ and N₂ and IR spectroscopy of the residues on heating in air at various temperatures.At ordinary pressure, the compounds are thermally stable up to the melting points. After melting, they show high vapor pressure, combustion in O₂ atmosphere and isomerization to ammonium thiocyanate, with the exception of Me₄Tu.Financially supported by the Italian MURST.     

Formation of a Hydroxo-bridged Dinuclear Ru(III)/Ru(III) Complex from <Emphasis Type="Italic">N</Emphasis>-Methylimidazole and [Ru<Emphasis Type="Italic">Cp</Emphasis>(CH<Subscript>3</Subscript>CN)<Subscript>3</Subscript>]<Superscript>+</Superscript>

Summary. The reaction of [RuCp(CH₃CN)₃]PF₆ with 1 equiv of N-Me-imidazole results in the quantitative formation of [RuCp(¹N-N-Me-imidazole)(CH₃CN)₂]PF₆ (1) featuring a ¹N rather than a ¹C bound N-Me-imidazole ligand. According to DFT/B3LYP calculations, ¹N coordination of N-Me-imidazole is preferred over ¹C coordination by 25.5kJ/mol. Upon exposure to air 1 reacts with oxygen and water to afford the novel hydroxo-bridged dinuclear complex of [Ru₂Cp₂(¹N-N-Me-imidazole)₂(-OH)₂](PF₆)₂ (2) featuring a metal-metal single bond. The dimeric nature of 2 was confirmed by a single-crystal X-ray structure analysis.     

Thermal Studies of Cobalt(II), Nickel(II) and Copper(II) Complexes of 4-(Sulfonylazido Phenylazo) Pyrazolones

The thermal decompositions of cobalt(II), nickel(II) and copper(II) complexes of4-(3'-sulfonylazido-6'-methoxyphenylazo)-1-phenyl-3-methyl-2-pyrazolin-5-one H(D¹–SO₂N₃) and 4-(4'-sulfonylazido phenylazo)-3-phenyl-3-methyl-2-pyrazolin-5-one H(D²–SO₂N₃) were studied by thermogravimetry. The decomposition in all cases takes place along two stages. The first stage is due to the elimination of water and nitrogen molecules with the formation of tetracoordinate complexes containing nitrene reactive species[M(DSO₂N:)₂]. The second stage represents the decomposition of the material to the metal oxide. The kinetics of the decomposition were examined by using Coats–Redfern, the decomposition in all complexes was found to be first order for the first and second stages. The activation energies and other activation parameters (H^* and S^* and G^*) were computed and related to the bonding and stereochemistry of the complexes.This revised version was published online in November 2005 with corrections to the Cover Date.     

Hydrolysis of the Peptide Bond in N-Acetylated L-Methionylglycine Catalyzed by Various Palladium(II) Complexes: Dependence of the Hydrolytic Reactions on the Nature of the Chelate Ligand in cis-[Pd( L)(H 2O) 2] 21 Complexes

Summary. Hydrolytic reactions between various palladium(II) complexes of the type cis-[Pd(L)(H₂O)₂]²⁺ in which L is ethylenediamine (en), 1,2-propylenediamine (1,2-pn), isobutylenediamine (ibn), 1,2-diaminocyclohexane (1,2-dach), N-methylethylenediamine (Meen), N,N,N,N-tetramethylethylenediamine (Me₄en), S-methyl L-cysteine (MeS-L-HCys), L-methionine (L-HMet), and 2,5-dithiahexane (dth) and dipeptide N-acetylated L-methionylglycine (MeCOMet-Gly) were studied by ¹H NMR spectroscopy. The reactions were carried out in the pH range 2.0–2.5 and at 50°C. In all these reactions, palladium(II) complex bound to a methionine residue effects the regioselective cleavage of the amide bond involving the carboxylic group of methionine. We found that the rate of hydrolysis and mechanism of this reaction are strongly dependent from the nature of the chelate ligand L in palladium(II) complexes of the type cis-[Pd(L)(H₂O)₂]²⁺.     

Tetrabutylammonium Salts of Ruthenium(II) Nitroso Complexes

The paper describes synthesis of (nBu₄N)₂[RuNOCl₅](I), (nBu₄N)₂[RuNOCl₄OH](II), (nBu₄N)₂×[RuNOCl₄OH]·6H₂O (III), and (nBu₄N)₂[RuNOCl₅]· 2(nBu₄N)₂[RuNOCl₄(H₂O)]·2H₂O (IV). The complexes were studied by IR spectroscopy and powder Xray and crystal Xray analyses. The structures are built up of [RuNOCl₅]^2- (I, IV), [RuNOCl₄OH]^2- (II, III), and [RuNOCl₄(H₂O)]^- (IV) complex anions, (nBu₄N)⁺ cations, and crystal water molecules (III, IV). The substances are moderately soluble in water; highly soluble in polar organic solvents, such as acetone, ethanol, chloroform, methylene chloride; and almost insoluble in carbon tetrachloride and toluene. Under storage in light, the compounds decompose from the surface; in darkness I and II are stable, whereas III and IV can lose part of the crystal water.     

Reactions of N-phenyl-o-semiquinonediimine complexes of nickel and platinum with carbonyl-containing low-valence iron and rhenium compounds

The reactions of o-semiquinonediimine complexes M[o-(NH)(NPh)C₆H₄]₂ (M = Ni (1) or Pt (2)) with carbonyl-containing iron and rhenium compounds were studied. The reactions of complexes 1 or 2 with Fe(CO)₅ afforded the Fe₂(CO)₆[-(NH)(NPh)C₆H₄] complex (3) containing the bridging N-phenyl-o-phenylenediamide ligand in high yield. The reaction of the Re(CO)₂(NO)Cl₂(thf) complex with complex 2 gave rise to the unusual mononuclear rhenium(iii) complex, viz., Re(Ph)[-¹-o-(NH)(NHPh)C₆H₄](CO)(NO)Cl₂ (4), no changes in the geometry of N-phenyl-o-phenylenediamine bound to the Re(NO)(CO)₂Cl₂ fragment being observed. The reaction of complex 2 with the Re(CO)₅Cl complex, which has been preliminarily treated with silver triflate, afforded the heterometallic complex (CO)Pt[-N,N-o-(N)(NPh)C₆H₄]₂ReCl[(NH)(NPh)C₆H₄]. The structures of the resulting complexes were established by X-ray diffraction analysis.     

Anion‐controlled Syntheses and Crystal Structures of a Pair of Novel Azide‐bridged Copper(II) Complexes Constructed from 4‐Chloro‐2‐[(2‐dimethylaminoethylimino)methyl]phenol

A pair of novel azide‐bridged polynuclear copper(II) complexes, [CuL(μ_1,1‐N₃)]_n ( 1 ) and [Cu₄L₂(CH₃COO)₂(μ_1,1‐N₃)₄] ( 2 ) (L = 4‐chloro‐2‐[(2‐dimethylaminoethylimino)methyl]phenolate), have been obtained from the same Schiff base ligand and an identical synthetic procedure using anions of the metal salts as the only independent variable. Complex 1 was synthesized using copper(II) nitrate, while complex 2 was synthesized using the copper(II) acetate as the salt. Both of the complexes show novel supramolecular structures in their crystals as elucidated by X‐ray analyses. The polynuclear complex 1 contains [CuL(μ_1,1‐N₃)]_n units as the building blocks, crystallizes in the Pbca space group. The tetra‐nuclear complex 2 contains [Cu₄L₂(CH₃COO)₂(μ_1,1‐N₃)₄] units as the building blocks, crystallizes in the space group.     

N‐Methylimidazolkomplexe des Berylliums: [Be(Me‐Im)4]I2 und [Be3(μ‐OH)3(Me‐Im)6]Cl3

Tetra(N‐methylimidazole)‐beryllium‐di‐iodide, [Be(Me‐Im)₄]I₂ ( 1 ), was prepared from beryllium powder and iodine in N‐methylimidazole suspension to give yellow single crystal plates, which were characterized by X‐ray diffraction and IR spectroscopy. Compound 1 crystallizes tetragonally in the space group I 2d with four formula units per unit cell. Lattice dimensions at 100(2) K: a = b = 1784.9(1), c = 696.2(1) pm, R₁ = 0.0238. The structure consists of homoleptic dications [Be(Me‐Im)₄]²⁺ with short Be–N distances of 170.3(3) pm and iodide ions with weak interionic C–H ··· I contacts. Experiments to yield crystalline products from reactions of N‐methylimidazole with BeCl₂ and (Ph₄P)₂[Be₂Cl₆], respectively, in dichloromethane solutions were unsuccessful. However, single crystals of [Be₃(μ‐OH)₃(Me‐Im)₆]Cl₃ ( 2 ) were obtained from these solutions in the presence of moisture air. According to X‐ray diffraction studies, two different crystal individuals ( 2a and 2b ) result, depending on the starting materials BeCl₂ and (Ph₄P)₂[Be₂Cl₆], respectively [ 2a : Space group P2₁/n, Z = 4; 2b : Space group P , Z = 2]. As a side‐product from the reaction of N‐methylimidazole with (Ph₄P)₂[Be₂Cl₆] single crystals of (Ph₄P)Cl·CH₂Cl₂ ( 3 ) were identified crystallographically (P2₁/n, Z = 4) which are isotypical with the corresponding known bromide (Ph₄P)Br·CH₂Cl₂.     

The designed synthesis and crystallographic characterization of three novel heterotrimetallic linear complexes of [Et4N][(Ph3P)2{M′S2 MS2Fe}Cl2] (M=Mo,M′=Ag;M=W,M′=Cu,Ag)

The complexes [Et₄N][(Ph₃P)₂{MS₂ MS₂Fe}Cl₂] (M=Mo,M=Ag;M=W,M=Cu, Ag) have been obtained by reaction of [Et₄N]₂[S₂ MS₂FeCl₂] (M=Mo, W) with Cu(PPh₃)₃Cl or Ag(PPh₃)₃NO₃ in MeCN/CH₂Cl₂, respectively. Crystal data for [Et₄N][(PPh₃)₂ {AgS₂MoS₂Fe}Cl₂] (I): triclinic, P (No. 2),Z=2,a=13.41(1)Å,b=15.54(1)Å,c=12.30(1)Å, =105.24(6)°, =94.63(7)°, =101.38(6)°, andV=2399(4)ų. The bond lengths of Mo-Fe bond and the Mo-Ag distance are 2.756(2)Å and 3.033(2)Å, respectively. Crystal data for [Et₄N][(PPh₃)₂ {AgS₂WS₂Fe}Cl₂] (II): triclinic, P (No. 2),Z=2,a=13.457(5))Å,b=15.601(6)Å,c=12.338(4)Å, =105.20(3)°, =94.61(4)°, =101.43(4)°, andV=2426(2)ų. The bond length of W-Fe bond and the W-Ag distance are 2.786(2)Å and 3.076(1)Å, respectively. Crystal data for [Et₄N][(PPh₃)₂ {CuS₂WS₂Fe}Cl₂] (III): triclinic, P (No. 2),Z=2,a=13.498(5)Å,b=15.372(4)Å,c=12.340(4)Å, =105.54(2)°, =93.32(3)°, =101.40(3)°, andV=2401(1)ų. The bond lengths of W-Fe bond and the W-Cu bond are 2.800(1)Å and 2.851(1)Å, respectively.     

Three New 1D Polymeric Zinc(II) and Cadmium(II) Azido Complexes Containing Noncoordinated Pyridine-<Emphasis Type="Italic">N</Emphasis>-oxide or 3-Picoline-<Emphasis Type="Italic">N</Emphasis>-oxide

Summary. The interaction of pyridine-N-oxide (pyNO) and 3-picoline-N-oxide (3picNO) with zinc(II) and cadmium(II) azides afforded complexes with empirical formulae Zn(N₃)₂(pyNO)(H₂O)₂, Zn(N₃)₂(3picNO)₂(H₂O)₂ and Cd(N₃)₂(3picNO)₂(H₂O)₂. The IR spectra of these complexes are measured and discussed. X-Ray single crystal diffraction showed for the first complex, which should be formulated as {[Zn(N₃)₂(H₂O)₂](pyNO)}_n, to consist of 1D chains of trans-[Zn(N₃)₂(H₂O)₂]_n, double end-on (-1,1) azido bridges and noncoordinated pyNO molecules. The other two complexes are isomorphous containing 1D trans-[M(N₃)₂(H₂O)₂]_n, double (-1,1) azido bridges, and hydrogen bonded noncoordinated 3picNO molecules. Each pyridine-N-oxide molecule forms three hydrogen bonds, whereas the 3-picoline-N-oxides form two hydrogen bonds. The metal centers exhibit distorted octahedral geometry.Received March 5, 2003; accepted May 15, 2003 Published online September 11,2003     

Interligand interactions involved in the molecular recognition between copper(II) complexes and adenine or related purines

The available crystal structure information in the CSD database on ternary species prepared by the reaction of diverse copper(II) complexes (CuL) and purine, adenine and guanine or related purine derivatives is considered in order to deepen the intra-molecular interligand interactions affecting the molecular recognition patterns of the ‘metal complex + purine nucleobase’ and closely related systems. The degree of protonation and the possibilities of different tautomeric forms in the purine-like moieties are taken into account. The main conclusion is a general trend to form a CuN(purine-like) coordination bond which can be reinforced by an intra-molecular interligand H-bonding interaction. NH(purines)A (O or Cl acceptor) or NH(amino ligand L)O6(oxo-purines) are commonly observed. In addition, selected examples revealed that the presence of a variety of non-coordinating groups in L or in the purine-like nucleobases can significantly influence the structurally observed molecular recognition pattern. Moreover, examples are known where binuclear cores of the types Cu^II₂(μ₂-N3,N9-adeninate)₄(aqua)₂ or Cu^I₂(μ₂-N3,N9-adeninate)₂(aqua)₂ recognise CuL chelates by means of the expectable pattern (CuN7 coordination bond + N6HO(L) interaction).