Preparation,NMR studies and crystal structure of mononuclear and dinuclear Pd(II) and Pt(II) complexes that contain 1,2-bis[3-(3,5-dimethyl-1-pyrazolyl)-2-thiapropyl]benzene

The reaction between 1,2-bis[3-(3,5-dimethyl-1-pyrazolyl)-2-thiapropyl]benzene (bddf) and [MCl₂(CH₃CN)₂] (M = Pd(II), Pt(II)) in a 1:1 M/L ratio in CH₂Cl₂ or acetonitrile solution, respectively, gave the complexes trans-[MCl₂(bddf)] (M = Pd(II) (1), Pt(II) (4)), and in a 2:1 M/L ratio led to [M₂Cl₄(bddf)] (M = Pd(II) (2), Pt(II) (5)). Treatment of 1 and 4 with AgBF₄ and NaBPh₄, respectively, gave the compounds [Pd(bddf)](BF₄)₂ (3) and [Pt(bddf)](BPh₄)₂ (6). When complexes 3 and 6 were heated under reflux in a solution of Et₄NBr in CH₂Cl₂/CH₃OH (1:1) for 24 h, analogous complexes to 1 and 4 with bromides instead of chlorides bonded to the metallic centre were obtained. These complexes were characterised by elemental analyses, conductivity measurements, infrared, ¹H, ¹H{¹⁹⁵Pt}, ¹³C{¹H}, ¹⁹⁵Pt{¹H} NMR, HSQC and NOESY spectroscopies. The X-ray crystal structure of the complex [Pd(bddf)](BF₄)₂ · H₂O has been determined. The metal atom is tetracoordinated by the two azine nitrogen atoms of the pyrazole rings and two thioether groups.     

Coordination properties of N2S (1,5-bis(3,5-dimethyl-1-pyrazolyl)-3-thiapentane) or N2S2 (1,8-bis(3,5-dimethyl-1-pyrazolyl)-3,6-dithiaoctane or 1,2-bis[3-(3,5-dimethyl-1-pyrazolyl)-2-thiapropyl]benzene) donor ligands toward Rh(I)

The 1,5-bis(3,5-dimethyl-1-pyrazolyl)-3-thiapentane ligand (bdtp) reacts with [Rh(COD)(THF)₂][BF₄] to give [Rh(COD)(bdtp)][BF₄] ([1][BF₄]), which is fluxional in solution on the NMR time scale. Its further treatment with carbon monoxide leads to a displacement of the 1,5-cyclooctadiene ligand, generating a mixture of two complexes, namely, [Rh(CO)₂(bdtp)][BF₄] ([2][BF₄]) and [Rh(CO)(bdtp-κ³N,N,S)][BF₄] ([3][BF₄]). In solution, [2][BF₄] exists as a mixture of two isomers, [Rh(CO)₂(bdtp-κ²N,N)]⁺ ([2a]⁺) and [Rh(CO)₂(bdtp-κ³N,N,S)]⁺ ([2b]⁺; major isomer) rapidly interconverting on the NMR time scale. At room temperature, [2][BF₄] easily loses one molecule of carbon monoxide to give [3][BF₄]. The latter is prone to react with carbon monoxide to partially regenerate [2][BF₄]. The ligands 1,2-bis[3-(3,5-dimethyl-1-pyrazolyl)-2-thiapropyl]benzene (bddf) and 1,8-bis(3,5-dimethyl-1-pyrazolyl)-3,6-dithiaoctane (bddo) are seen to react with two equivalents of [Rh(COD)(THF)₂][BF₄] to give the dinuclear complexes [Rh₂(bddf)(COD)₂][BF₄]₂ ([4][BF₄]₂) and [Rh₂(bddo)(COD)₂][BF₄]₂ ([5][BF₄]₂), respectively. In such complexes, the ligand acts as a double pincer holding two rhodium atoms through a chelation involving S and N donor atoms. Bubbling carbon monoxide into a solution of [4][BF₄]₂ results in loss of the COD ligand and carbonylation to give [Rh₂(bddf)(CO)₄][BF₄]₂ ([6][BF₄]₂). The single-crystal X-ray structures of [3][CF₃SO₃], [5][BF₄]₂ and [6][BF₄]₂ are reported.     

Structural and spectroscopic trends in mononuclear arylchalcogenolato-palladium(II) and -platinum(II) complexes: Crystal structures of [M(TeAr)2(dppe)] {M = palladium, platinum; Ar = phenyl, 2-thienyl; dppe = 1,2-bis(diphenylphosphino)ethane}

A series of mononuclear [M(EAr)₂(dppe)] [M = Pd, Pt; E = Se, Te; Ar = phenyl, 2-thienyl; dppe = 1,2-bis(diphenylphosphino)ethane] complexes has been prepared in good yields by the reactions of [MCl₂(dppe)] and corresponding ArE⁻ with a special emphasis on the aryltellurolato palladium and -platinum complexes for which the existing structural information is virtually non-existent. The complexes have crystallized in five isomorphic groups: (1) [Pd(SePh)₂(dppe)] and [Pt(SePh)₂(dppe)], (2) [Pd(TePh)₂(dppe)] and [Pt(TePh)₂(dppe)], (3) [Pd(SeTh)₂(dppe)], (4) [Pt(SeTh)₂(dppe)] and [Pd(TeTh)₂(dppe)], and (5) [Pt(TePh)₂(dppe)]. In addition, solvated [Pd(TePh)₂(dppe)] · CH₃OH and [Pd(TeTh)₂(dppe)] · 1/2CH₂Cl₂ could be isolated and structurally characterized. The metal atom in each complex exhibits an approximate square-planar coordination. The Pd-Se, Pt-Se, Pd-Te, and Pt-Te bonds span a range of 2.4350(7)-2.4828(7) Å, 2.442(1)-2.511(1) Å, 2.5871(7)-2.6704(8) Å, and 2.6053(6)-2.6594(9) Å, respectively, and the respective Pd-P and Pt-P bond distances are 2.265(2)-2.295(2) Å and 2.247(2)-2.270(2) Å. The orientation of the arylchalcogenolato ligands with respect to the M(E₂)(P₂) plane has been found to depend on the E-M-E bond angle. The NMR spectroscopic information indicates the formation of only cis-[M(EAr)₂(dppe)] complexes in solution. The trends in the ³¹P, ⁷⁷Se, ¹²⁵Te, and ¹⁹⁵Pt chemical shifts expectedly depend on the nature of metal, chalcogen, and aryl group. Each trend can be considered independently of other factors. The ⁷⁷Se or ¹²⁵Te resonances appear as second-order multiplets in case of palladium and platinum complexes, respectively. Spectral simulation has yielded all relevant coupling constants.     

Preparation and characterisation of mononuclear Pd(II) complexes with 1,8-bis(3,5-dimethyl-1-pyrazolyl)-3,6-dithiaoctane (bddo) ligand: Spectroscopy studies and crystal structure of trans-[Pd(SCN)2(bddo)]

Mononuclear palladium(II) complexes containing a pyrazole-thioether ligand, with general formula trans-[Pd(X)₂(bddo)] (X = CN⁻ (1), SCN⁻ (2) or N₃⁻ (3); bddo = 1,8-bis(3,5-dimethyl-1-pyrazolyl)-3,6-dithiaoctane), have been prepared. Similar reactivity carried out with pyridine or triphenylphosphine has been assayed. When pyridine is used, a mixture of [Pd(bddo)(py)₂](BF₄)₂ ([4](BF₄)₂) and [Pd(bddo)](BF₄)₂ is obtained. When triphenylphosphine is used, only [Pd(bddo)](BF₄)₂ is obtained. The complexes have been characterised by elemental analyses, conductivity measurements, IR and NMR spectroscopies. X-ray crystal structure of trans-[Pd(SCN)₂(bddo)] (2) is presented. In this complex the metal atom is coordinated by the two azine nitrogen atoms of the pyrazole rings and two SCN⁻ anions in trans disposition.     

Syntheses and characterization of nickel(II), zinc(II) and palladium(II) complexes derived from three pyrazole-based polydentate ligands

Two pyrazole-based polydentate ligands, 1,3-bis(5-methyl-3-phenylpyrazol-1-yl)-propan-2-ol (Hmppzpo) and 1,3-bis(5-methyl-3-p-isopropylphenylpyrazol-1-yl)-propan-2-ol (Hmcpzpo), have been synthesized. A third ligand, 1,3-bis(3,5-dimethylpyrazol-1-yl)-propan-2-ol (Hdmpzpo), has been synthetically modified. Seven new M(II) coordination compounds of general formula M₂L₂X₂ (M?=?Zn, Ni; X?=?NO₃ or ClO₄; L?=?dmpzpo, mppzpo or mcpzpo) or MLX (M?=?Pd; L?=?dmpzpo; X?=?Cl) were synthesized and structurally characterized by elemental analysis and FT-IR analysis. The crystal structures of [Zn₂(μ-dmpzpo-O,N,N′)₂(NO₃)₂]?·?2H₂O (1?·?2H₂O), [Ni₂(μ-dmpzpo-O,N,N′)₂(CH₃CN)₂](ClO₄)₂ (2) and Pd(μ-dmpzpo-N,N′)Cl₂ (4) were determined by single-crystal X-ray crystallography. The crystal structures show that complexes 1?·?2H₂O and 2 are center-symmetric dinuclear compounds, with two metal ions bridged by two alkoxo groups and each metal ion with a distorted square-pyramidal environment. The palladium complex, 4, displayed square-planar coordination geometry around the Pd(II) ion with trans arrangement.     

Coordination and reactivity of white phosphorus and tetraphosphorus trisulphide in the presence of the fragment CpFe(dppe) [dppe = 1,2-bis(diphenylphosphino)ethane]

The reaction of [CpFe(dppe)Cl] (1) [dppe = 1,2-bis(diphenylphosphino)ethane] with one equivalent of P₄ or P₄S₃ in the presence of a chloride scavenger, TlPF₆ or AgOTf (OTf = triflate, OSO₂CF₃), affords the complexes [CpFe(dppe)(η¹-P₄)]PF₆ (2) and [CpFe(dppe)(η¹-P_basal-P₄S₃)]OTf (3) which contain the tetrahedral P₄ and the mixed P₄S₃ cage molecule η¹-bound to the metal. Both P₄ and P₄S₃ yield furthermore the dimetal compounds [{CpFe(dppe)}₂(μ,η^1:1-P₄)](PF₆)₂ (4) and [{CpFe(dppe)}₂(μ,η^1:1-P_apical-P_basal-P₄S₃)](OTf)₂ (5), which contain the tetrahedral P₄ or the mixed-cage P₄S₃ molecule tethering two ruthenium fragments via two phosphorus atoms. All the compounds have been characterized by elemental analyses and NMR measurements. The crystal structure of 4 has been determined by X-ray diffraction methods. The complexes readily react with excess water under mild reaction conditions and the outcoming products have been identified.     

Displacement of neutral nitrogen donors by chloride in [Pt(SNS)(R-py)](ClO4)2 (SNS = 2,6-bis(methylthiomethyl)pyridine; R-py = pyridines): A reactivity comparison between meta- and para-substituted pyridines

The kinetics of the process [Pt(SNS)(R-py)]²⁺ + Cl⁻ → [Pt(SNS)Cl]⁺ + R-py {SNS = 2,6-bis(methylsulfanylmethyl)pyridine; R-py = meta- or para-substituted pyridines covering a wide range of basicity} were studied in methanol at 25 °C. The reactions obey the usual two-term rate law observed in the substitution reactions of square-planar d⁸ complexes. The plots of log k₂ {k₂ = second-order rate constants} against the pK_a of the heterocycles conjugate acids highlighted a different sensitivity of the two groups of N-donors to changes in basicity, thepara-substituted pyridines (4R-py) showing a weaker dependence on pK_a than the meta-substituted (3R-py). The results have been explained on the basis of a π-acidity difference between 3R-py and 4R-py which influences the reaction ground state.     

Syntheses and crystal structures of cadmium(II)X2-hexamethylenetetramine (X = Br/I/SCN) coordination polymers having different dimensionality

Four new coordination polymers of cadmium(II) with hexamethylenetetramine (htm) have been synthesized and characterized by routine physicochemical techniques as well as by X-ray single crystal structure analysis. They are [CdBr(htm)(SCN)(H₂O)₂·CH₃OH]_n (1), [CdI(htm)(SCN)(H₂O)₂·0.5(CH₃OH)]_n (2), [Cd₂(htm)₃(SCN)₄(H₂O)]_n·nH₂O (3) and [Cd₃Br₆(htm)₂(H₂O)₅·(htm)(H₂O)₆]_n (4). Complexes 1, 2 and 3 exhibit 1D polymeric structure and complex 4 shows a 2D undulated layered arrangement, containing Cd₆(htm)₆ hexagonal units as building block, which extended to a 3D supramolecular architecture through hydrogen bonding. Thorough thermal investigation suggest that as far as the thermal stability of Cd(II)-htm bond is concerned it attains the maximum in complex 1 and minimum in complex 4. In case of complex 3 the thermal study inferred that CdS end product was obtained at ∼730 °C, whereas in case of other complexes the thermally stable end product remained unidentified. Solid state fluorescence study shows that all the complexes are luminescent at room temperature except complex 3.     

Synthesis,characterization, crystal structure and thermal analysis of a copper(II) mononuclear compound with 2,6- bis (3,5-dimethyl- N -pyrazolyl)pyridine (bdmpp) and selenocyanate as ligands

A single crystal of the copper(II) compound, [Cu(bdmpp)(SeCN)₂], 2, was obtained and its crystal structure was determined by X-ray diffraction methods. The complex was characterized by elemental, thermal and FTIR analysis. The FTIR analysis of the complex clearly shows the SeCN peaks at 2096 and 2061?cm^?1 which did not exist in the free organic ligand (bdmpp). X-ray analysis showed that 2 crystallized in the monoclinic space group P2₁/c. Cu(II) has a distorted trigonal bipyramidal coordination involving three N atoms from the ligand and two N atoms from the selenocyanate group.     

Palladium(II) and platinum(II) saccharinate complexes containing pyridine and 3-acetylpyridine: Synthesis, crystal structures, fluorescence and thermal properties

New palladium(II) and platinum(II) complexes of saccharinate (sac), trans-[Pd(py)₂(sac)₂] (1), cis-[Pt(py)₂(sac)₂] (2), trans-[Pd(3-acpy)₂(sac)₂] (3) and cis-[Pt(3-acpy)₂(sac)₂] (4) (py = pyridine and 3-acpy = 3-acetylpyridine) have been synthesized. Elemental analysis, UV-Vis, IR, NMR and TG/DTA characterizations have been carried out. The structures of 1-4 were determined by X-ray diffraction. The palladium(II) and platinum(II) ions are coordinated by two N-bonded sac ligands, and two nitrogen atoms of py or 3-acpy, forming a distorted square-planar geometry. The palladium(II) complexes (1 and 3) are trans isomers, while the platinum(II) complexes (2 and 4) are cis isomers. The mononuclear species in the solid state are connected by weak intermolecular C-H?O hydrogen bonds, C-H?π and π?π stacking interactions. The platinum(II) complexes show significant fluorescence at the room temperature.     

Reaction of [CpRu(CH3CN)3]PF6 with bidentate ligands: structural characterization of [{CpRu(CH3CN)2}2(μ-η-dppe)](PF6)2 [dppe=1,2-bis(diphenylphosphino)ethane]

The reaction of [CpRu(CH₃CN)₃]PF₆ with the bidentate ligands L-L=1,2-bis(diphenylphosphino)ethane, dppe, and (1-diphenylarsino-2-diphenylphosphino)ethane, dpadppe, affords mononuclear or dinuclear complexes of formula [CpRu(η²-L-L)(CH₃CN)]PF₆, [{CpRu(CH₃CN)₂}₂(μ-η^1:1-L-L)](PF₆)₂ and [{CpRu(CH₃CN)}₂(μ-η^1:1-L-L)₂](PF₆)₂ (L-L=dppe, dpadppe). All of the compounds are characterized by microanalysis and NMR [¹H and ³¹P{¹H}] spectroscopy. The crystal structure of [{CpRu(CH₃CN)₂}₂(μ-η^1:1-dppe)](PF₆)₂ has been determined by X-ray diffraction analysis. The complex exhibits a dppe ligand bridging two CpRu(CH₃CN)₂ fragments.     

Oxidative addition to dimethylplatinum (II) compounds containing bulky nitrogen ligands: crystal structures of compounds [PtMe3I{(Me2NCH2CH2NCH)Ar}] (Ar = phenanthryl or anthryl)

Oxidative addition of methyl iodide to platinum (II) compounds [PtMe₂{(Me₂NCH₂CH₂NCH)Ar}] (Ar = phenanthryl or anthryl) produced the corresponding platinum (IV) compounds. Processes aimed at reducing the steric crowding at the coordination sphere of the platinum (IV) centre such as C-C restricted rotation of the pendant part of the ligand leading to rotamers and isomerisation of the CN moiety have been detected in solution. The obtained platinum (IV) compounds were characterised by elemental analyses, mass spectrometry and NMR spectroscopy. According to the crystallographic characterisation, the anthracene derivative gave an E conformer while a Z conformation was obtained for the phenanthrene derivative. In order to rationalize the experimental results, DFT calculations have been performed.     

Structural and Spectral Study of Nickel(II) Complexes of Pyridyl bis{3‐piperidyl‐, bis{hexamethyleneiminyl‐, bis{N(4)‐diethyl‐, and bis{N(4)‐dipropylthiosemicarbazones}

Pyridyl bis(N(4)‐substituted thiosemicarbazones), in which the substituents replacing the NH₂ group on the thiosemicarbazone moieties are piperidyl, H₂Plpip; hexamethyleneiminyl, H₂Plhexim; diethylamino, H₂Pl4DE; and dipropylamino, H₂Pl4DP, have been synthesized. These bis(thiosemicarbazones) and their nickel(II) complexes have been characterized with IR, electronic, mass, and ¹H and ¹³C NMR spectra. Crystal structures have been solved for H₂Plpip and all four nickel(II) complexes. H₂Plpip does not possess hydrogen bonding between the thiosemicarbazone moieties, but is in the Z isomeric form with intramolecular hydrogen bonding from both thiosemicarbazone moieties to pyridine nitrogen atoms. The nickel(II) complexes possess square‐planar N₂S₂ (i. e., imine nitrogen and thiolato sulfur atoms) centers and the two pyridine ring nitrogen atoms are not coordinated.     

Synthesis,spectral properties,crystal structures and biological activity of copper(II) pyridinecarboxylates with N -heterocyclic ligands

Synthesis and characterization of four new 2,6-dimethoxynicotinate (2,6-(MeO)₂nic) copper(II) monomeric complexes [Cu(2,6-(MeO)₂nic)₂(py)₂] (py is pyridine), [Cu{2,6-(MeO)₂nic}₂(Etnic)₂(H₂O)] (Etnic is ethylnicotinate), [Cu{2,6-(MeO)₂nic}₂(Et₂nia)₂(H₂O)₂] (Et₂nia is N,N-diethylnicotinamide) as well as of the polymeric complex [Cu{2,6-(MeO)₂nic}₂(ron)₂] _n (ron is ronicol) are reported. The characterizations were based on elemental analysis, infrared, electronic and EPR spectra. Crystal structures of two of the complexes have been determined. The copper(II) of [Cu{2,6-(MeO)₂nic}₂(py)₂] has a distorted tetragonal-bipyramidal (4 + 2) coordination environment. Both 2,6-(MeO)₂nic anions are asymmetrically chelating. The Cu(II) of [Cu{2,6-(MeO)₂nic}₂(Etnic)₂(H₂O)] is pentacoordinate in a slightly distorted tetragonal-pyramidal arrangement by two trans nitrogens, each of one Etnic, by two oxygens, each of the carboxyl group of one unidentate 2,6-(MeO)₂nic and the axial position occupied by water at a longer distance. Antimicrobial effects of the complexes have been tested on various strains of bacteria, yeasts and filamentous fungi. While the 2,6-(MeO)₂nicH alone did not influence the model bacteria growth, dimeric [Cu{2,6-(MeO)₂nic}₂(H₂O)]₂ and polymeric [Cu{2,6-(MeO)₂nic}₂(ron)₂] _n have pronounced influence on the growth of Staphylococcus aureus, Escherichia coli and Candida parapsilosis.     

Synthesis,crystal structure,spectroscopy and magnetism of a trinuclear nickel(II) complex with 3,5-pyrazoledicarboxylic acid as bridge ligands

A new complex of [Ni₃(dcp)₂(H₂O)₁₀] (1) (H₃dcp = 3,5-pyrazoledicarboxylic acid) has been synthesized from H₃dcp and Ni(NO₃)₂·6H₂O by hydrothermal reaction. Complex 1 has the discrete trinuclear structure. Three Ni(II) ions are bridged by two dcp³⁻ ligands, with 10 coordinated water molecules as terminal ligands. The molecules of [Ni₃(dcp)₂(H₂O)₁₀] extend into three-dimensional supramolecular architectures by intermolecular O–H···O hydrogen bonds as well as π-π stacking interactions. Magnetic susceptibility measurement shows that a weak antiferromagnetic interaction is operative between nickel(II) ions and an excellent simulation of the experimental data gives D = 5.27 cm⁻¹, J = −2.19 cm⁻¹ and g = 2.05.     

Experimental and computational study on [2,6-bis(3,5-dimethyl-N-pyrazolyl)pyridine]-(dithiocyanato)mercury(II)

The mercury complex of 2,6-bis(3,5-dimethyl-N-pyrazolyl)pyridine (bdmpp) has been synthesized and characterized by X-ray diffraction, IR, UV–Vis and TGA–DTA methods. The structure consists of units in which the mercury atom is pentacoordinate with two sulfur and three nitrogen atoms. [Hg(bdmpp)(SCN)₂] has a distorted square pyramid geometry.     

Syntheses,characterizations and crystal structures of two new complexes, [Co2(CH2 =C(CH3)CO2)4(phen)2(H2O)2] and [Pb2(CH2 =C(CH3)CO2)4(phen)2]

Two new complexes, [Co₂(CH₂=C(CH₃)CO₂)₄(phen)₂(H₂O)₂] (1) and [Pb₂(CH₂=C(CH₃)CO₂)₄(phen)₂] (phen = 1,10-phenanthroline) (2), have been synthesized and structurally characterized by single crystal X-ray diffraction methods. There are two cocrystallized conformers of [Co(CH₂=C(CH₃)CO₂)₂(phen)(H₂O)] in the asymmetric unit of 1 with the Co atoms displaying similar coordination modes. In the asymmetric unit of 2, there exist two crystallographically independent [Pb(CH₂=C(CH₃)CO₂)₂(phen)] molecules with the Pb atoms showing completely different coordination geometries. Weak intermolecular interactions such as hydrogen bonding and π–π stacking are responsible for the supramolecular assembly and stabilization of the crystal structures of 1 and 2. The complexes are characterized by elemental analysis, IR spectra, and UV–Vis spectra. The fluorescent properties of 2 are also discussed.