Synthesis,crystal structures and catalytic activities of new palladium(II)–bis(oxazoline) complexes

Palladium–bis(oxazoline) complexes (Pd-BOX-A and Pd-BOX-B) were synthesized and characterized by ¹H, ¹³C NMR, IR and elemental analysis. The molecular structures of the complexes were confirmed by single-crystal X-ray analysis. In both cases, the palladium center is coordinated by the nitrogen atoms of the two oxazoline rings and two chloride ligands in a distorted square planar geometry. Despite the fact that the bis(oxazoline) ligand is achiral, the asymmetrical substitution on the phenyl spacer and the rigid backbone of the complex Pd-BOX-A induce inherent chirality and the compound crystallizes as a racemic mixture. Both complexes were found to be highly effective catalysts for Suzuki–Miyaura, Mizoroki–Heck and Sonogashira cross-coupling reactions. They also show excellent catalytic activities toward carbonylative coupling reactions.     

Synthesis,crystal structures and photoluminescence of three new Mn(II) coordination polymers assembled from 2,4′-diphenic acid

Three new metal coordination polymers, [Mn(Hdpa)₂(4,4′-bipy)₂] _n (1), [Mn(dpa)(1,10-phen)(H₂O)] _n (2), and [Mn(dpa)(2,2′-bipy)] _n (3) (H₂dpa = 2,4′-biphenyl-dicarboxylic acid, 4,4′-bipy = 4,4′-bipyridine, 1,10-phen = 1,10-phenanthroline, and 2,2′-bipy = 2,2′-bipyridine), have been synthesized and characterized by elemental analysis, IR, and X-ray diffraction. Single-crystal X-ray analyses reveal that 2,4′-diphenic acid is a bridging ligand, exhibiting three coordination modes to link metal ions: μ ₁-η ¹: η ¹/μ ₀-η ⁰: η ⁰; μ ₂-η ²: η ⁰/μ ₁-η ¹: η ⁰; and μ ₂-η ¹: η ¹/μ ₂-η ¹: η ¹. Intermolecular hydrogen bonds in 1 lead to a zigzag chain. In 2, the 2-D supramolecular arrays extended along b-axis through π–π interactions between 1,10-phen. The dinuclear paddle-wheel second building units (SBUs) constructed by four dpa^2? ligands in 3 are linked by dpa^2? into double-strand chains. The fluorescence of H₂dpa and 1–3 are also determined.     

Synthesis and ligand substituion chemistry of dinuclear,phosphido-bridged complexes of manganese. X-ray crystal structures of Mn2(μ-H)(μ-Cy2P)(CO)7(PCy2H)(1) and Mn2(μ-H)(μ-Cy2P)(CO)6(PMe32

Reaction of Mn₂ (CO)₁₀ with two equivalents of dicyclohexylphosphine in toluene at 110° produces Mn₂ (μ-H)(μ-Cy₂P)(CO)₇(PCy₂H) (1) in 60% yield. Interaction of 1 with excess trimethylphosphine produces Mn₂(μ-H)(μ-Cy₂P)(CO)₆ (PMe₃)(₂ (2) in 90% yield. The X-ray crystal structures of 1 and 2 have been determined. Both structures contain two Mn atoms bridged by a Cy₂P group and a hydridge. In each case, the metal atoms exhibit distorted octahedral geometry, with the phosphines occupying positions trans to the P atom of the bridging dicyclohexylphosphine. A metal-metal distance of ca. 2.9 Å separates the manganese atoms in both complexes.     

Synthesis and characterization of diorganotin(IV) derivatives from rhodanine (HRd): crystal structures of [(PhCH2)2Sn(Rd)(μ-OH)]2 and [n-Bu2Sn(Rd)(μ-OH)]2

The diorganotin(IV) complexes, [R₂Sn(Rd)(μ-OH)]₂ (R?=?Me (1), PhCH₂ (2), n-Bu (3), Ph (4); HRd?=?rhodanine), have been synthesized and characterized by IR and multinuclear (¹H, ¹³C, ¹¹⁹Sn) NMR spectroscopy. The structures of complexes 2 and 3 have been determined by single-crystal X-ray diffraction. Both crystal structures of 2 and 3 show the presence of asymmetrically bridging hydroxy groups leading to an Sn₂O₂ unit. Each atom in complex 1 is also coordinated by an N atom of ligand and two C atoms of the alkyl groups, so the Sn environment is based on a trigonal bipyramid. While in complex 2, a weak intermolecular Sn–O interaction has also been found between the two adjacent molecules, so the geometry of the Sn atom can be best described as six-coordinate octahedral. The salient feature of the supramolecular structure of complex 3 is that of a 1D polymer, in which the discrete molecules are connected through weak intermolecular Sn?···?O interactions.     

Synthesis,crystal structures and magnetic properties of two new nickel(II) complexes with α-amino acid Schiff base

Two nickel(II) complexes [Ni(napgly)(MeOH)] _n (1) and [Ni(napphe)(H₂O)₂(MeOH)] · H₂O (2), where the tridentate Schiff-base ligands H₂napgly and H₂napphe are condensed from 2-hydroxyl-1-naphthaldehyde with glycine and L-phenylalanine, respectively, were prepared and structurally characterized. In 1, two inversion-related Ni(II) ions were bridged by two O atoms from the phenolate groups of two napgly anions, forming a centrosymmetric dimeric unit which was further linked by carboxylate groups to give a two-dimensional network. Magnetic susceptibility studies performed on the complex revealed anti-ferromagnetic coupling between the metal centers. In 2, the crystal structures of the complex displayed a distorted octahedral coordination geometry in which the ONO-donor Schiff base was bonded to the metal. Intermolecular H-bonds linked the compound into a 2-D layer structure.     

Synthesis,magnetochemical studies and X-ray molecular structures of some mononuclear copper(II)–1H-pyrazole adducts and mono(μ-pyrazolate) bridged dicopper(II) complexes derived from N-salicylidenearoylhydrazines

1H-Pyrazole complexes, [Cu(HL)HPz Cl] nH₂O and [Cu(L)HPz] nH₂O were prepared and characterized, where HL and L, respectively, refer to the mononegative and dinegative N-salicylidenearoylhydrazine anions. The X-ray crystal and molecular structure of [monochloro(N-salicylidenebenzoylhydrazinato)ONO(−1)monopyrazole] copper(II) monohydrate, [Cu(HSBzh)HPz Cl] H₂O, and [(N-salicylidenebenzoylhydrazinato)ONO(−2)monopyrazole] copper(II) hemihydrate, [Cu(SBzh)HPz] 1/2H₂O, were determined. The Cu(II) in [Cu(HSBzh)HPz Cl] H₂O is in a distorted square pyramidal environment and is bound in the equatorial plane with the mononegative tridentate aroylhydrazone anion and pyrazole nitrogen, the axial fifth coordination site is occupied by a chloride ion. On the other hand, the complex [Cu(SBzh)HPz] 1/2H₂O consists of two monomeric crystallographically independent but chemically similar molecules. In each molecule, the Cu(II) is in a distorted square planar geometry and is coordinated to the dinegative tridentate aroylhydrazone via the phenoxy oxygen, azomethine nitrogen and enolimide oxygen, and the fourth coordination site is occupied by the pyrazole nitrogen. The mono(μ-pyrazolate) dicopper(II) complexes, K[Cu₂(L)₂Pz] nH₂O, were also prepared and the X-ray molecular structure of K₂[Cu₄(SBzh)₄(Pz)₂] 2H₂O 1/2CH₃OH was determined. In this complex, two copper(II) atoms are bridged by only one pyrazolate anion forming a dicopper mono(μ-pyrazolate) unit. Each two units are connected together by a five coordinate K⁺ cation forming a tetranuclear assembly. These tetranuclear assemblies are connected together by another K⁺ cation forming a supramolecular structure. Variable temperature magnetic studies on these pyrazolate complexes indicated antiferromagnetic behaviour with −2J values varying from 25 to 36 cm⁻¹.     

Thermal,spectroscopic, X-ray powder diffraction,fluorescence, and structural studies of [Pb(μ-4-pyc)(μ-Br)] n,new mixed-anion lead(II) 3-D coordination polymers

A new Pb(II) 3-D coordination polymer, [Pb(μ-4-pyc)(μ-Br)] _n (1) {4-Hpyc = 4-pyridinecarboxylic acid}, has been synthesized and characterized by elemental analysis, IR spectroscopy, and structure determined by single-crystal X-ray diffraction. The crystal structure consists of 3-D polymeric units. The thermal stability of 1 was studied by thermal gravimetric and differential thermal analyses.     

Synthesis and Structure of Catena-[Bis(2-Methylimidazole)(μ-Phthalato)cobaltate(II)]

A new coordination compound [Co(Pht)(2-MeIm)₂] (I), where Pht^2–is the deprotonated radical of o-phthalic acid (H₂Pht) and 2-MeIm is 2-methylimidazole, was synthesized. Its structure was established using X-ray diffraction analysis. The crystal is orthorhombic: space group Pca2₁, a= 15.350(3), b= 7.957(2), c= 13.997(3) Å, (calcd.) = 1.505 g/cm³, and Z= 4. The tetrahedral coordination of the Co(II) atom includes two N atoms of two 2-methylimidazole molecules and two oxygen atoms of two carboxyl groups from different acid radicals. The Co–N distances are equal to 2.022(2) and 2.031(2) Å, while the Co–O distances are 1.972(2) and 2.000(2) Å. The carboxyl groups of the Pht^2–radical and the aromatic nucleus form angles of 47.2° and 35.9°, whereas the angle formed by the carboxyl groups themselves is 50.3°. Compound Iis a polymer, which is confirmed by the 1,6-bridging function of the o-phthalic acid radical. The Co···Co distance in a chain is equal to 7.367 Å. Separate chains are united in the crystal into a framework via N–H···O hydrogen bonds.     

Air- and moisture-stable cationic (diphosphine)palladium(II) complexes as hydroamination catalysts: X-ray crystal structures of two [(diphosphine)Pd(NCMe)(OH2)]2+[OTf]−2 complexes

A series of cationic (diphosphine)palladium(II) complexes have been prepared and fully characterized, including two crystal structures. These complexes were evaluated as catalysts for the hydroamination of acyclic alkenes. The reactivity of the catalysts is dependent on the nature of the diphosphine ligand and the substituents on the amine and alkene substrates.     

Synthesis and X-ray crystal structure of the electron-deficient metal carbonyl cluster [Os3(CO)5(μ3-H)(μ-H)(μ-PtBu2)2(μ-Ph2PCH2PPh2)]

The reaction of [Os₃(CO)₁₀(μ-dppm)] (1) with ^tBu₂PH in refluxing diglyme results in the electron-deficient metal cluster complex [Os₃(CO)₅(μ₃-H)(μ-P^tBu₂)₂(μ-dppm)] (2) (dppm = Ph₂PCH₂PPh₂) in good yields. The molecular structure of 2 has been established by a single crystal X-ray structure analysis. In contrast to the known homologue [Ru₃(μ-CO)(CO)₄(μ₃-H)(μ-H)(μ-P^tBu₂)₂(μ-dppm)] (3), no bridging carbonyl ligand was found in 2. The electronically unsaturated cluster 2 does not react with carbon monoxide under elevated pressure, therefore 2 seems to be coordinatively saturated by reason of the high steric demands of the phosphido ligands.     

Synthesis and X-ray crystal structures of N,N,N′,N′-tetraalkylpyridine-2,6-dithiocarboxamides (S-dapt) complexes of cobalt(II) and nickel(II)

Reactions of anhydrous CoX₂ (X?=?Br^?, SCN^?) and Ni(ClO₄)₂ with N,N,N′,N′-tetraisobutylpyridine-2,6-dithiocarboxamides (S-dbpt), N,N,N′,N′-tetraisopropyl pyridine-2,6-dithiocarboxamides (S-dppt), and N,N,N′,N′-tetraethylpyridine-2,6-dithiocarboxamides (S-dept) lead to the formation of [Co(S-dbpt)Br₂] (1), [Co(S-dppt)(SCN)₂] (2), and [Ni(S-dept)₂]·(ClO₄)₂·H₂O (3), respectively. The X-ray crystal structures of the three S-dapt ligands and three complexes along with spectroscopic analyzes are presented. The molecular structure investigations of the S-dapt ligands show that the thiamide planes are twisted with respect to the pyridine ring, which is more in the case of phenyl groups. The structures of the Co(II) complexes reveal that an increase in steric crowding on the amide side arms of the ligands has no substantial effect on the geometry adopted by the corresponding complexes. The Co(II) gives only 1?:?1 five-coordinate, ion-paired complexes with a distorted square pyramidal geometry. Ni(II), on the other hand, prefers an octahedral geometry with 1?:?2 metal–ligand ratio. The coordination behavior of S-dapt has been compared to the analogous oxo(O-daap) ligands. Lesser propensity of S atom to get involved in H-bonding interactions ensures an S-N-S type of tridentate coordination by S-dapt.     

Mercury(II) and Lead(II) complexes with 2,2′-Bis (4,5-dimethylimidazole) – syntheses,characterization and crystal structures of [M(DmImH)(SCN)2], (M = Hg2+ and Pb2+ )

Mercury(II) and lead(II) complexes with 2,2′-bis(4,5-dimethylimidazole) (DmImH), [Hg(DmImH)(SCN)₂] and [Pb(DmImH)(NCS)₂], have been synthesized and characterized by IR specta and elemental analyses. The molecular structure of [Pb(DmImH)(NCS)₂] _n is polymeric with four-coordinate lead atoms. The [Hg(DmImH)(SCN)₂] complex is built up of monomeric Hg(SCN)₂ units with one “DmImH” ligand coordinated to the Hg atom via the two N atoms in a distorted tetrahedral environment. The thiocyanate ligands are coordinated to lead via nitrogen, but to mercury via the sulfur. There are π–π stacking interactions between the parallel aromatic rings in the mercury(II) complex.     

Synthesis and spectral studies of some new dimeric [(μ-Cl)2M2(L)2 · xTHF] [M = Zn(II) and Hg(II)] complexes containing Schiff-base ligands

A series of binuclear Schiff-base complexes of zinc(II) and mercury(II) containing bidentate ligands (HL) [HL?=?salicylidene-2-methyl-1-aminobenzene (HL¹), salicylidene-2-aminopyridine (HL²), and salicylidene-3-nitro-1-aminobenzene (HL³)] with “N” and “O” donors have been synthesized by simple metathetic reactions of anhydrous metal chlorides with sodium salts of Schiff bases (in tetrahydrofuran (THF)/MeOH) in equimolar ratio to produce [(µ-Cl)₂M₂(L)₂?·?xTHF] [where M?=?Zn(II) and Hg(II); L?=?HL¹, HL², and HL³; x?=?0 for (1), (4), (6) and x?=?2 for (2), (3), (5)]. The main emphasis on the complexes [(µ-Cl)₂M₂(L)₂?·?2THF] (2), (3), and (5) is given due to their five-coordinate environment around metal ions. The complexes have been characterized by elemental analyses (M, Cl, C, H, N), melting point, and spectral (FT-IR, ¹H-NMR, and ¹³C-NMR) studies. The structural composition of the complexes has been determined by FAB-MS spectral studies. FAB-MS showed the isotopic molecular ion peak [M⁺] and fragments supporting the formulation. Powder X-ray diffraction study of 6 is also reported showing the crystallite size (404.5?Å) of the complex.     

Syntheses,crystal structures,and electrochemical studies of diiron complexes from the reactions of [Et3NH][(μ-RS) Fe2(CO)6(μ-CO)] with isothiocyanates

Reactions of [Et₃NH][(μ-MeO₂CCH₂S)Fe₂(CO)₆(μ-CO)] in situ generated from the mixture of MeO₂CCH₂SH, Et₃N, and Fe₃(CO)₁₂ with 2-C₅H₄NNCS, 3-C₅H₄NNCS, and EtNCS in THF, form 1, (μ-MeO₂CCH₂S)Fe₂(CO)₅(μ-k²N,S:k²C-2-C₅H₄NNHCS), 2, (μ-MeO₂CCH₂S)Fe₂(CO)₆(μ-k²C,S-3-C₅H₄NNHCS), and 3, (μ-MeO₂CCH₂S)Fe₂(CO)₆(μ-k²C,S-EtNHCS). Reaction of [Et₃NH][(μ-PhS)Fe₂(CO)₆(μ-CO)] in situ formed from the mixture of PhSH, Et₃N, and Fe₃(CO)₁₂ with EtNCS affords 4, (μ-PhS)Fe₂(CO)₆(μ-k²C,S-EtNHCS). Reaction of [Et₃NH][(μ-EtS)Fe₂(CO)₆(μ-CO)] in situ produced from the mixture of EtSH, Et₃N, and Fe₃(CO)₁₂ with EtNCS offers 5, (μ-EtS)Fe₂(CO)₆(μ-k²C,S-EtNHCS). All new complexes have been fully characterized by EA, IR, ¹H NMR, and ¹³C NMR and structurally determined by X-ray crystallography. Electrochemical studies on 2 and 5 confirm that 2 shows high H₂-producing activity.     

Heterobimetallic Cu(II)–Hg(II) polynuclear complexes containing Hg(SCN)42− unit – Synthesis,spectroscopic investigations,X-ray studies and magnetic properties

Three novel heterobimetallic polymers with Hg(SCN)₄^2? as a linker have been synthesised and characterized by means of IR, EPR, magnetic measurements and single crystal X-ray. All the obtained compounds [Cu(bpzm)Hg(SCN)₄]_n (1), [Cu(bdmpzm)Hg(SCN)₄]_n (2) and [Cu(dpa)Hg(SCN)₄]_n (3) form supramolecular framework structures. The 1 creates a three-dimensional coordination polymer, and 2 and 3 form two-dimensional nets extending along crystallographic (0 1 0) plane. Each octahedrally coordinated Cu(II) atom of 1 connects to four mercury ions through four thiocyanate bridges, and each Hg(II) ion is bridged with four copper ions via four thiocyanate bridges. The Cu(II) ions of 2 and 3 display a pyramidal coordination geometry, and they are connected to three mercury ions through three thiocyanate bridges, one thiocyanate ion is nonbridging group.     

Mercury(II) complexes of pyrrolidinedithiocarbamate,crystal structure of bis{[μ2-(pyrrolidinedithiocarbamato-S,S ′)(pyrrolidinedithiocarbamato-S,S ′)mercury(II)]}

Mercury(II) complexes of pyrrolidinedithiocarbamate (PDTC) having the general formula [Hg(PDTC)X] (X = Cl^?, SCN^?, and CN^?) and [Hg(PDTC)₂] have been prepared and characterized by elemental analysis, IR, and NMR. The crystal structure of [Hg(PDTC)₂] has also been determined by X-ray crystallography, showing that the complex is a centrosymmetric dimer, [Hg₂(PDTC)₄] (bis[µ²-(pyrrolidinedithiocarbamato-S,S′)(pyrrolidinedithiocarbamato-S,S′)mercury(II)]) (1). The solid-state structure of 1 contains two crystallographically equivalent Hg(II) centers in a distorted tetrahedron.     

Synthesis,crystal structures,and magnetic properties of cobalt(II) and nickel(II) complexes of 2,2′-bipyridine-6,6′-dicarboxylate: three three-dimensional networks formed via hydrogen bonding interactions

Three Co(II) and Ni(II) complexes, namely [Co(bpdc)(H₂O)₂] (1), [Ni(bpdc)(H₂O)₂] (2), and [Co₂(bpdc)₂(prz)_0.5(H₂O)₃]·0.5H₂O (3) (H₂bpdc = 2,2′-bipyridine-6,6′-dicarboxylic acid and prz = piperazine), have been synthesized from H₂bpdc and the corresponding metal salts under hydrothermal conditions. The complexes were characterized by physico-chemical and spectroscopic methods, as well as by X-ray crystallography. Compounds 1 and 2 both consist of neutral mononuclear molecules, of [Co(bpdc)(H₂O)₂] and [Ni(bpdc)(H₂O)₂], respectively. Compound 3 consists of a mononuclear molecule of [Co(bpdc)(H₂O)₂] and a binuclear molecule of [Co₂(bpdc)₂prz (H₂O)₂]. The discrete neutral complexes 1–3 further extend their structures into three-dimensional supramolecular architectures by intermolecular O–H⋯O and C–H⋯O hydrogen bonds as well as π–π stacking interactions. Magnetic susceptibility measurements show that complex 3 exhibits weak ferromagnetic interactions between the two Co(II) ions bridged by the prz ligand, with C = 5.41 cm³ mol⁻¹ K and θ = +27.6 K, respectively.     

Synthesis,crystal structures,thermal, and spectroscopic properties of four new metal(II) (M = Co,Ni, Cu,Hg) complexes of 2-benzoylbenzoate with 3-picoline

Four 2-benzoylbenzoate (bba) complexes, [Co(bba)₂(H₂O)₂(3-pic)₂] (1), [Ni(bba)₂(H₂O)₂(3-pic)₂] (2), [Cu(bba)₂(3-pic)₂] (3), and [Hg(bba)₂(3-pic)₂] (4), have been synthesized and characterized by IR spectra, thermal (TG, DTG, and DTA) analysis, and single crystal X-ray diffraction. All the complexes consist of neutral monomeric units with 1 and 2 crystallizing in the orthorhombic (P n a 2₁), 3 in triclinic (P 1), and 4 in monoclinic (P2₁/c) crystal systems. The metal(II) ions exhibit distorted octahedral coordination for 1, 2, and 3 and mercury(II) exhibits distorted trigonal prism coordination. In 1 and 2, bba is monodentate, whereas in 3 and 4 bba is bidentate. 3-Picoline (3-pic) is a classical N-monodentate ligand. Bba are coordinated to metal(II) with carboxylates and IR spectra of all complexes display characteristic absorptions of carboxylate {υ(OCO)_asym and υ(OCO)_sym}. Thermogravimetric (TG) analyses show that 1 and 2 are thermally stable (T_decomp.?>?60°C) and 3 and 4 are thermally stable (T_{decomp .} ?>?120°C).     

Synthesis, crystal structures, and nonlinear optical (NLO) properties of new Schiff-base nickel(II) complexes. Toward a new type of molecular switch?

An H2L Schiff-base ligand that was obtained from the monocondensation of diaminomaleonitrile and 4-(diethylamino)salicylaldehyde is reported together with four related nickel(II) complexes formulated as [Ni(L)(L')] (L' = MePhCHNH2, iPrNH2, Py, and PPh3). Crystal structures have been solved for H2L, [Ni(L)(MePhCHNH2)], and [Ni(L)(iPrNH2)]. Surprisingly, the complexation process leads to the formation of a rather unusual nickel amido (-NH-Ni(II)) bond by deprotonation of the primary amine of H2L. A reduction of the quadratic hyperpolarizability (beta) from 38 x 10(-30) to 17.5 x 10(-30) cm5 esu(-1) is evidenced on H2L upon metal complexation by the electric-field-induced second-harmonic (EFISH) technique. Qualitative ZINDO/SCI quantum chemical calculations indicate that, in [Ni(L)(MePhCHNH2)], the beta orientation strongly depends on the laser wavelength. In particular, a beta rotation strictly equal to 90 degrees could be obtained with 1.022 microm incident light on passing from [Ni(L)(MePhCHNH2] to a hypothetical [Ni(HL)(MePhCHNH2]+ protonated complex, thus raising the possibility for a new type of molecular switch.     

Synthesis and X-ray crystal structure of a novel organometallic (μ3-oxido)(μ3-imido) trinuclear iridium complex

Reaction of the organometallic aqua ion [Cp*Ir(H(2)O)(3)](2+) with tert-butyl(trimethylsilyl)amine in acetone yielded a novel trinuclear (μ(3)-oxido)(μ(3)-imido)pentamethylcyclopentadienyliridium(III) complex, [(Cp*Ir)(3)(O)(N(t)Bu)](2+). Single crystal structure analyses show the complex can be isolated both in the double salt ((t)BuNH(3))[(Cp*Ir)(3)(O)(N(t)Bu)](CF(3)SO(3))(3) (1) and in the simple triflate [(Cp*Ir)(3)(O)(N(t)Bu)](CF(3)SO(3))(2) (2). The double salt is stabilized by hydrogen bonding between the tert-butylammonium ion and the three triflate anions. It is the first time that a trinuclear (μ(3)-oxido)(μ(3)-imido) transition metal complex has been structurally characterized.