Amparo Caubet

Copper complexes with a pyrazole derivative ligand. Crystal structure of tetrakis{[(3,5-bis(pyridin-2-yl)pyrazolate)-(aqua)copper(II) nitrate monohydrate}

Abstract Reaction of the pyrazole-derived ligand 3,5-bis(pyridin-2-yl)pyrazole (bpypz) with Cu(NO3)2, CuCl2 and CuBr2 yields polynuclear copper(II) compounds with remarkable structural and magnetic properties. The magnetic behaviour was studied by fitting the experimental data with a dimer and tetramer magnetic model. Strong antiferromagnetic exchange interactions were found in all cases. The molecular structure of the nitrate compound was solved by X-ray diffraction methods. The compound is tetranuclear, orthorhombic, space group Fddd, a = 18.572(4), b = 23.816(8), c = 27.337(9) A, V= 12092 A3, Z = 8.

Assembly of cyclopalladated units: synthesis, characterisation, X-ray crystal structure and study of the reactivity of the tetrametallic cyclopalladated complex [Pd{C6H4CHN(C6H42-O)}]4·2CHCl3

The reaction of the equimolar amounts of the Schiff base C 6 H 4 CHN(C 6 H 4 2-OH) ( 1 ) and palladium(II) acetate in refluxing methanol for 2 h produces [Pd{C 6 H 4 CHN(C 6 H 4 2-O)}] 4 ( 2 )·2CHCl 3 . The X-ray crystal structure of 2 ·2CHCl 3 reveals that it contains a central non-planar eight-membered ring “Pd 4 O 4 ” formed by the self-assembly of four cyclopalladated fragments in which the ligand behaves as a [C, N, O] 2− terdentate ligand and the oxygen atoms act as bridges between the monomeric units. The reaction of 2 with triphenylphosphine or 1,1′-bis(diphenylphosphino)ferrocene (dppf) produces the opening of the central “Pd 4 O 4 ” core and the formation of the monomeric derivative [Pd{C 6 H 4 CHN(C 6 H 4 2-O)}(PPh 3 )] ( 3 )·CH 2 Cl 2 and the trimetallic complex [{Pd[C 6 H 4 CHN(C 6 H 4 2-O)]} 2 (μ-dppf)] ( 4 ), respectively. In 3 and 4 , the ligand also behaves as a dianionic and terdentate [C, N, O] 2− group, thus indicating that the PdO bond exhibits remarkable stability. The X-ray crystal structure of 3 ·CH 2 Cl 2 confirmed the mode of binding of the Schiff base and a trans arrangement between the imine nitrogen and the PPh 3 ligand. A comparative study of the spectrochemical properties of compounds 2 – 4 is also reported.

Methionine and histidine Pd(II) and Pt(II) complexes: Crystal structures and spectroscopic properties

X-ray crystal structures and properties of the two Pd(II) complexes, [Pd(L-methionine)Cl2] and [Pd(L-histidine)Cl2] and the properties of the corresponding complexes of Pt(II) are described. The amino acids are bound to the metal ion by N (from the NH2 group) and by S in the case of the methionine, or N (from the imidazolic group) in the case of the histidine. Reactions of these compounds with nucleotides have been studied and found to yield several ternary compounds with 5′-GMP and 5′-IMP. In all cases, the Cl− ion has been replaced by one molecule of nucleotide. The metal ion seems to be coordinated to the N(7) atom of the 5′-GMP purine ring and to the N(7) or N(3) of the 5′-IMP purine ring.

Cobalt(II) complexes with pyrazole-derived ligands: crystal structure of {bis[3-phenyl-5-(2-pyridyl) pyrazole]aquachlorocobalt(II)}chloride monohydrate

Abstract The synthesis of the new pyrazole-derived ligands 3-phenyl-5-(2-pyridyl) pyrazole (HL0) and 3-phenyl-5-(6-methyl-(2-pyridyl))pyrazole (HL1) and their Co(II) complexes is reported. Elemental analyses, conductivity measurements and IR and UV–Vis spectroscopies defined all complexes. 1H and 13C NMR spectroscopies were also used in the characterization of ligands. The crystal and molecular structures of [Co(HL0)2Cl(H2O)]Cl·H2O, consisting of discrete ions and water molecules linked by hydrogen bonds, are also reported. The hexacoordinated metal atom is bonded to two pyridinic nitrogens, two pyrazolic nitrogens (one of each nitrogen belonging to two different ligands), one chlorine atom and one water molecule, forming a distorted octahedral environment. The ligands are not exactly planar and the arrangement of ligands is cis, with a dihedral angle between the two mean planes of ligands of 89.21(6)°. The degree of distortion from regular octahedral geometry is compared to that of closely related structures.

Mixed bridged, dinuclear copper(II) complexes with dinucleating, pyrazole derived ligands

Abstract Mixed μ-OH or μ-halide, μ-pyrazolato dinuclear copper(II) complexes of 3,5-bis(pyridin-2-yl)pyrazole (HL), 3-(6-methylpyridin-2-yl)-5-(pyridin-2-yl)pyrazole (HL1) and 3,5-bis(6-methylpyridin-2-yl)pyrazole (HL2) have been synthesized and characterized. Their spectral and magnetic behaviour are also reported. The μ-OH compounds behave as a Curie-Weiss paramagnet, while the μ-halide complexes exhibit strong antiferromagnetic interactions.

Platinum(II) and Palladium(II) Compounds Containing Chiral Thioimines

A comparative study of the reactivity of the optically pure thioimine: (SC)-(−)-C6H5−CH=N−CH(CO2Me)−CH2−CH2− SMe (1) versus platinum(II) and palladium(II) salts is reported. The reaction of 1 with cis-[PtCl2(dmso)2] leads to the cycloplatinated derivative (SC,RS)-(+)-[Pt{C6H4−CH=N−CH(CO2Me)−CH2−CH2−SMe}Cl] (3a). The absolute configuration of 3a has been established unambiguously by X-ray diffraction: orthorhombic, with a = 8.979 (4), b = 9.605(9), c = 18.205(6) A, α = β = γ = 90.0°, space group P212121. Compound 3a contains a [6.5.6] tricyclic system generated by the fusion of a phenyl ring, a five-membered platinacycle and a six-membered chelate ring formed by the coordination of the nitrogen and sulfur to the platinum. When 1 was treated with Na2[PdCl4] in methanol at room temperature a (7.9:1) mixture of the two diastereomers {(SC,RS)-5a and (SC,SS)-5b} of cis-[Pd{C6H5−CH=N−CH(CO2Me)−CH2−CH2−SMe}Cl2] (5) was formed. However, when the reaction was performed in the presence of sodium acetate, the activation of the σ(C−H) bond took place giving the cyclopalladated complex: (SC,RS)-(+)-[Pd{C6H4−CH=N−CH(CO2Me)−CH2− CH2−SMe}}Cl] (6a). In 6a, the ligand acts as a monoanionic (C,N,S)− terdentate group. The study of the reactivity of 3a and 6a with PPh3 is also reported.

Palladium (II) and platinum (II) compounds containing bi- and terdentate ferrocenyl ligands. X-ray crystal structure of cis-[Pd{(η5-C5H5)Fe{(η5-C5H4)–CHN–CH2–CH2–N(CH3)2]}Cl2]

The synthesis, characterization and study of the three ferrocenyl Schiff bases: [(η 5 -C 5 H 5 )Fe{(η 5 -C 5 H 4 )–CHN–CH 2 –CH 2 –N(CH 3 ) 2 }] ( 1a ), [(η 5 -C 5 H 5 )Fe{(η 5 -C 5 H 4 )–CHN–CH 2 –CH 2 –S–CH 2 –CH 3 }] ( 1b ) and [(η 5 -C 5 H 5 )Fe{(η 5 -C 5 H 4 )–CHN–CH(COOCH 3 )–CH 2 –CH 2 –S–CH 3 }] ( 1c ) are reported. Reactivity studies of these substrates versus palladium (II) and platinum (II) salts have allowed us to isolate and characterize different sorts of complex. The coordination complexes: cis -[M(ligand)Cl 2 ] {where M=Pd ( 2a – 2c ) or Pt ( 3a – 3c )} were prepared by treatment of the corresponding ligand and Na 2 [PdCl 4 ] (for 2a – 2c ) or cis -[PtCl 2 (dmso) 2 ] (for 3a – 3c ) in methanol. In compounds 2 , 3a – c the ligand acts as a neutral bidentate group. The cyclopalladated complex: [Pd{(η 5 -C 5 H 5 )Fe[(η 5 -C 5 H 3 )–CHN–CH 2 –CH 2 –N(CH 3 ) 2 ]}Cl] ( 4a ) can be isolated by reaction of stoichiometric amounts of 1a , Na 2 [PdCl 4 ] and Na(CH 3 COO) · 3H 2 O in methanol for 8 days. In complex 4a the ligand acts as a monoanionic (C, N, N′) − terdentate group. The reaction of compound 4a with an equimolar amount of PPh 3 produces [Pd{(η 5 -C 5 H 5 )Fe[(η 5 -C 5 H 3 )–CHN–CH 2 –CH 2 –N(CH 3 ) 2 ]}Cl(PPh 3 )], in which the ligand acts as a monoanionic (C, N) − bidentate ligand. All the compounds included in this study have been characterized by infrared and NMR spectroscopy and complex 2a has also been characterized structurally: monoclinic, P 2 1 / m , with a =6.034(2) A, b =14.502(2) A, c =10.236(2) A and β =104.61(2)°. The crystal structure of complex 2a reveals that the imine adopts the Z -form.

Palladium(II) and Platinum(II) Polyamine Complexes: X‐Ray Crystal Structures of (SP‐4‐2)‐Chloro{N‐[(3‐amino‐κN)propyl]propane‐1,3‐diamine‐κN,κN′}palladium(1+) Tetrachloropalladate (2–) (2 : 1) and (R,S)‐Tetrachloro[μ‐(spermine)]dipalladium(II) (={μ‐{N,N′‐Bis[(3‐amino‐κN)propyl]butane‐1,4‐diamine‐κN:κN′}}tetrachlorodipalladium)

The reactivity of the polyamines L, i.e., N-(3-aminopropyl)propane-1,3-diamine (1), spermidine (=N-(3-aminopropyl)butane-1,4-diamine; 2), and spermine (=N,N′-bis(3-aminopropyl)butane-1,4-diamine; 3) vs. palladium(II) and platinum(II) salts is studied. These reactions allowed us to prepare and characterize a wide variety of PdII and PtII complexes containing the polyamines. Compounds of the general formula [MCl(L)]2[MCl4] (L=1; 1a: M=Pd; 1b: M=Pt) or [MCl(L)]Cl (L=1; 1′a: M=Pd; 1′b: M=Pt) were isolated after treatment of K2[MCl4] or cis-[MCl2(dmso)2] respectively, with 1. The reaction of K2[MCl4] with 2 led to [MCl(L)]2[MCl4] (L=2; 2a: M=Pd; 2b: M=Pt), while that with 3 gave the neutral dinuclear compounds [M2Cl4(L)] (L=3; 3a: M=Pd; 3b: M=Pt). A comparative study of the results obtained in these reactions allowed us to evaluate the influence of i) the number of N-atoms in the polyamine, ii) their basicity, and iii) the palladium or platinum salt, upon the nature of the final product. Compounds 1a and (R,S)-3a were characterized by their X-ray crystal-structure analysis. Both exhibited the monoclinic crystal system, 1a the space group P21/c, and 3a the space group P21/n.

Easy access to diastereomerically pure platinacycles

The synthesis of the first examples of diastereomerically pure platinacycles having simultaneously a chiral carbon and a sigma[Pt-C(sp(2), ferrocene)] bond is described.

Synthesis, characterisation and study of the reactivity of the first platinum(II) complex having a [C(sp2, ferrocene), N, N']-terdentate ligand

The study of the reactivity of [(η5-C5H5)Fe{(η5-C5H4)–CHN–(CH2)3–NMe2}] (1) with cis-[PtCl2(dmso)2] is reported. These studies have allowed the isolation and characterisation of two isomeric forms of cis-[Pt{(η5-C5H5)Fe[(η5-C5H4)–CHN–(CH2)3–NMe2])}Cl2] (2a and 2b), which differ in the conformation of the ligand [syn-(Z) in 2a and anti-(E) in 2b], and the first platinacycle containing a terdentate [C(sp2, ferrocene),N,N′]− ligand: [Pt{[(η5-C5H3)–CHN–(CH2)3–NMe2]Fe(η5-C5H5)}Cl] (3). The relative importance of the factors governing the formation of 3 is discussed. The X-ray crystal structures of 2a and 3 are described and confirm the mode of binding of the ligand to the platinum(II). The study of the reactivity of 3 with PPh3 or CH3I is also reported.