Synthetic and Structural Studies of N-Heterocyclic Carbene Complexes of Nickel

Transition metal complexes of stable N-heterocyclic carbenes have recently gained increasing attention as pre-catalysts for a number of important reactions primarily based on the analogy between N-heterocyclic carbenes and strong ó-donating tertiary phosphines,[1] Although a large number of transition-metal carbene complexes have been reported, very few incorporate chelating carbenes were reported.[2,3] Therefore, we have set out to prepare and study transition-metal compounds with chelating di-N-heterocyclic carbenes, and we now report new dicationic tetra(carbine)nickel(Ⅱ) complexes in this class (Scheme 1). Their structures have been determined by single-crystal X-ray diffraction studies (Figure 1).     

Crystal Structures and Characterizations of Bis(pyrrolidinedithiocarbamato) Cu(II) and Zn(II) Complexes

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Syntheses and Characterization of Pentacoordinate Organotin (Ⅳ) Complexes

Ten novel pentacoordinate organo-tin complexes were prepared and characterized. Singlecrystal structure determination by X-diffraction was made.     

Six-Nuclear Complexes of Platinum(II) and Palladium(II) with Mercamine and β-Mercaptoethanol

The platinum(II) and palladium(II) complexes [Pt₆(SCH₂CH₂NH₂)₈]Cl₄ and [Pd₆(SCH₂CH₂OH)₈ Cl₄· 5H₂O with mercamine and β-mercaptoethanol, respectively, were synthesized. It was found on the basis of the comparison of IR and X-ray electron spectra of the ligands and complexes, and also of the data of X-ray diffraction analysis that the bidentate coordination of ligands through sulfur and nitrogen atoms is realized in the platinum(II) complex. In the palladium(II) complex β-mercaptoethanol is coordinated in a mixed-mode type. In both complexes sulfur atoms of the ligands occupy a bridging position.     

η6-Arenetricarbonylchromium(0) Complexes in the Synthesis of 1,4-Benzodiazepines and Its Nucleophilic Substituted Products

Abstract

7-Chloro-5-carbomethoxy-1,3-dihydro-2H-1,4-benzodiazepines and its nucleophilic substituted products were synthesized via η⁶-arenetricarbonylchromium(0) intermediates. Ring enlargement of 5-chloro-N-chloroacetylisatin with hexamine in presence of Cr(CO)₆ led to the formation of 7-chloro-5-carbomethoxy-1,3-dihydro-2H-1,4-benzodiazepine in good yield with reduced reaction time. Nucleophilic substitutions on arene ring of η⁶-arenetricarbonylchromium(0) complexes with thiols, phenol, and primary amines were successfully carried out in decalin medium.     

Novel Synthesis of Haloaromatic Tertiary Alcohols Using (η6-Fluoroarene)tricarbonylchromium(0) Complexes

Regioselective synthesis of haloaromatic tertiary alcohols can be achieved by ortho deprotonation/electrophilic reactions of (η⁶- fluoroarene)Cr(CO)₃ complexes with halobenzophenones and metal removal. The coexistence of different halogens in the aromatic rings of these molecules make them unique within the group of tertiary alcohols.     

Porphyrins and Metalloporphyrins Combined with N-Heterocyclic Carbene (NHC) Gold(I) Complexes for Photodynamic Therapy Application: What Is the Weight of the Heavy Atom Effect?

The photophysical properties of two classes of porphyrins and metalloporphyrins linked to N-heterocyclic carbene (NHC) Au(I) complexes have been investigated by means of density functional theory and its time-dependent extension for their potential application in photodynamic therapy. For this purpose, the absorption spectra, the singlet–triplet energy gaps, and the spin–orbit coupling (SOC) constants have been determined. The obtained results show that all the studied compounds possess the appropriate properties to generate cytotoxic singlet molecular oxygen, and consequently, they can be employed as photosensitizers in photodynamic therapy. Nevertheless, on the basis of the computed SOCs and the analysis of the metal contribution to the involved molecular orbitals, a different influence in terms of the heavy atom effect in promoting the intersystem crossing process has been found as a function of the identity of the metal center and its position in the center of the porphyrin core or linked to the peripheral NHC.     

Synthesis and Structural Study of a N-Heterocyclic Carbene Trinuclear Silver(Ⅰ) Complex

The bis-benzimidazolium salt bis[2-(N-ethylbenzimidazoliumyl)ethyl]amine hexafluorophosphate(LH_2·(PF_6)_2) and its N-heterocyclic carbene silver(Ⅰ) complex[L_2Ag_3](PF_6)_3(1)have been prepared and characterized.In complex 1,a trinuclear silver(Ⅰ) architecture is formed by two tridentate ligands and three silver(I) atoms,in which one 12- and two 7-membered rings are contained.In the crystal packing of 1,1D chain and 2D supramolecular layer are formed via intermolecular weak interactions,including π…π interactions and C-H…π contacts.Additionally,the fluorescence emission spectra of LH_2-(PF_6)2 and 1 are described.     

Synthesis and Characterization of Aryl Acylguanidines and Their Copper(Ⅱ) Complexes

A series of eight N-mono-substituted aryl acylguanidines L~(1～8) were synthesized from the reactions of their parent acylthioureas and respective primary amines, including five R~1C(O)N=C(NHR~2)_2 with balanced arms(denoted as R~1–R~2–R~2: Ph–Ar'–Ar', L~1(1); Ph–Ar'–Ar', L~2(2); 1-Naph–Ar'–Ar', L~3(3); 1-Naph–Ar'–Ar', L~4(4); 2-Naph–Ar'–Ar', L`5(5); Ar' = 2,6-Me_2C_6H_3, Ar' = 2,6-iPr_2C_6H_3) and three R~1C(O)N=C(NHR~2)NHR~3 with unbalanced arms(denoted as R~1–R~2–R~3: Ph–Ar'–Ph, L~6(6); Ph–Ar' –Ph, L~7(7); Ph–Ar' –Ar', L~8(8)). Treatment of L~(1～5)(1～5) with copper acetate in a molar ratio of 2:1 in dichloromethane led to the formation of homoleptic Cu(Ⅱ) complexes trans-L_2~(n')Cu(9～13), in which the Cu(Ⅱ) center was stabilized by deprotonated ligands Ln'(n = 1～5) in the O,N-bidentate mode. When similar reactions of L~6(Ph–Ar'–Ph)(6) and L~7(Ph–Ar'–Ph)(7) that contain unbalanced arms were investigated, the Cu(Ⅱ) products trans-L_2~(6')Cu(14) and trans-L_2~(7')Cu(15) were formed by deprotonating the bulky amine groups in Ln(-NHAr' for L~6 and-NHAr' for L~7) rather than the-NHPh group. In sharp contrast, trans-L_2~(8')Cu(16) was obtained from two-arm unbalanced L~8(Ph–Ar'–Ar')(8) not by deprotonating the more bulky-NHAr' group but the relatively less bulky-NHAr' group. In a further exploration, the reaction of 1:1 mixed ligands Ln and Lm with copper acetate was found to give only homoleptic Cu(Ⅱ) complex L_2~(n')Cu instead of the heteroleptic one L~(n')CuL~(m'). The in vitro antibacterial activity of L~n was evaluated against S. aureus, E. coli and C. albicans by determining the minimum inhibitory concentrations(MICs) using Kirby-Bauer test.     

Synthesis and Magnetism of μ-IsophthalatoOxovanadium(Ⅱ) Binuclear Complexes

INTRoDUCTIONThestudyoflong-rangemagneticinteractiotisofbinuclearcom-plexeswithextendedbridgedstructureareofcurrentinterestinrecentyears.Inviewoftheeffectivebridgingfunctionofisophthalatedianion(abbreviatedasIPHTA),thispa-perdealswiththesguthesis,characterizationandrnagnetismoftwonewp-IPHTAoxo-vanadium(ll)binuclearcomplexes.Synthesisof[(Vo),(IPHTA)(phen),]SO4(1)Asolutionofpiperidiniumisophthalate'(134.4mg,O.4mmol)andphen(l44.2mg,o.8mmol)inmethanol(1omL)wasaddedslow1ytoamethanolsolut…     

Palladium(II) and Platinum(II) Complexes of N-Phenyl- and N-Ethyl-N′-pyrimidin-2-ylthiourea

Palladium(II) and platinum(II) complexes of N-ethyl-N′-pyrimidin-2-ylthiourea(HL¹) and N-phenyl-N′-pyrimidin-2-ylthiourea (HL²) have been prepared, and the complexes [M(HL)Cl₂], [Pt(L)₂], [Pd(HL¹)₂]Cl₂, and [Pd(L²)₂] (where M = Pd^II or Pt^II) were characterized. The spectroscopic data are consistent with coordination of thioureas as neutral or monoanionic ligands to Pd^II and Pt^II through S and a pyrimidine-N. The IR spectra show shifts of CS and pyrimidine ring stretch bands to lower and higher frequencies, respectively. The ¹H NMR spectra differentiate between H(4′) and H(6′) resonances and indicate downfield shifts for all protons of pyrimidine [H(4′), H(5′), and H(6′)], two resonances for two N?H protons for complexes containing the neutral ligand (HL), and only one N?H proton chemical shift for complexes containing the monoanion (L). ¹³C NMR chemical shifts of pyrimidine carbons are correlated with the type of bonding between Pd^II or Pt^II and pyrimidine-N. The magnetic susceptibilities suggest a diamagnetic planar structure for all complexes.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Synthesis and Crystal Structure of Cobalt(Ⅱ) and Copper(Ⅱ) Complexes Involving L-Aamino Alcohols

Two novel L-amino alcohol coordination cobalt and copper complexes I and Ⅱ were obtained separately from the direct reaction of L-plenylglycinol with Co(Ⅱ) acetate tetrahydrate in anhydrous ethanol and L-leucinol with Cu(Ⅱ) chloride dihydrate in anhydrous methanol. The structures of I and Ⅱ were determined by single-crystal X-ray diffraction and further characterized by elemental analysis and IR. For I: [Co3(C51H66N3O16)]2(OAc), monoclinic, space group P21, a = 15.022(3), b = 14.242(3), c = 28.922(6) , β = 98.944(4)o, V = 6112(2) 3, Z = 4, Dc = 1.339 g/cm3, the final R = 0.0860 for 21906 observed reflections with I 2(I). For Ⅱ: Cu2[C24H58N4O7Cl]Cl, orthorhombic, space group P212121, a = 6.1861(13), b = 20.838(4), c = 28.274(6) , V = 3644.6(13) 3, Z = 4, Dc = 1.310 g/cm3, the final R = 0.0642 for 11106 observed reflections with I 2(I). The complexes were then used to catalyze the Henry reaction and catalytic activity determined by 1H NMR.     

Synthesis and Properties of u-Oxamido Heterobinuclear Cu(Ⅱ)-Co(Ⅱ) Complexes

Three heterobinuclear complexes were synthesized, namely [Cu (oxpn) Co (L)2] (ClO4)2·xH2O(L= 2,2'-bipyridyl(bpy), 1,10-phenanthroline(phen) , and 5-nitro-1, 10-phenanthroline (NO2-phen)), where oxpn represents N, N'-bis(3-aminopropyl) oxam-ido. Based on 1R, elemental analysis, conductivity measurement and electronic spectra, these complexes were characterized by an extended oxamido-bridged structure with Cu(Ⅱ) in a planar environment and Co(Ⅱ) in a octahedral environment. The symmetry of the cation is very close to C2v.The complexes were also characterized with variable temperature (4~300K) magnetic susceptibility, and the data were fit for the susceptibility equation derived from spin Hamilton, H= -2JS1.S2-DSx12 by least square strategy. The exchange integral, J, was found to be -22.36 cm-1 (for bpy);-15.45 cm-1 (for phen); -19. 10cm-1(for NO2-phen), indicating that there is a weak antiferromagnetic spin-exchange interaction between the metal ions.     

Synthesis and Magnetic Properties of Fe(II) and Nd(III) Complexes of Poly(N-2-thiazolylacrylamide)

In recent years,the organic ferromagnets have drawn growing attention due to their characteristics of structural diversities,low density,and readily processing1-3.Design and synthesis of magnetic polymers are one of great challenges in today′s magnetic material research,and some significant achievements have been made in this field4,5.In this article,we describe the synthesis of acrylamide-type polymer with pendent thiazolyl groups(Scheme1).The as-prepared polymer exhibited better solubility …     

Vibrational spectroscope of complexes of platinum(0)—I. Tetrakis(triphenylphosphine)platinum(0) and Dioxygenbis(triphenylphosphine)platinum(0)

Assignment of i.r. and Raman spectra for Pt(PPh₃)₄ and Pt(O₂)(PPh₃)₂ yielded values for νPtP of 137 and 157 cm⁻¹ (Pt(PPh₃)₄); 132 (antisymmetric) and 145 cm⁻¹ (symmetric) (Pt(O₂)(PPh₃)₂). For the dioxygen complex, solution phase Raman spectra gave values for both ν PtO₂ modes for the first time. Data from the ¹⁶O₂, ¹⁶O¹⁸O and ¹⁸O₂ isotopomers were used in a normal coordinate analysis of the PtO₂ fragment. The OO stretching force constant (3.0 mdyn Å⁻¹) is consistent with extensive net π-back-donation into the π* m.o.s of the O₂ ligand.     

Syntheses and Crystal Structures of Hg(Ⅱ) and Ag(Ⅰ) Complexes Containing 2-Acetylpyridine-paminobenzoylhydrazone Ligand

The two complexes [HgI_2L](DMF)(1) and [AgL_2](ClO_4)(CH_3CN)(2) were synthesized from the reaction of Schiff base ligand(2-acetylpyridine-p-aminobenzoylhydrazone)(L) with HgI_2 or AgClO_4 respectively. The compounds are characterized by ~1H NMR,FTIR and elemental analysis. The structures of the ligand and two complexes are measured via single-crystal X-ray diffraction. In these two complexes,the structures are both distorted triangular bipyramids with five-coordinated centers.     

Syntheses and Crystal Structures of Zinc(II) and Nickel(II) Complexes Involving Reduced Nitroxide Radicals

1 INTRODUCTION The synthesis of new molecular magnetic mate- rials that combine transition metal ions and pure organic radicals as ligating sites has attracted much more attention in the last few years[1~4]. Nitronyl ni- troxide radicals, independently or in combination with metal ions, have been one of the most studied systems in molecular magnetism for understanding the radical-radical or metal-radical interactions as well as for synthesizing organic ferromagnets and metal-radical magne…     

Synthesis and Magnetic Studies of Oxamido-Bridged Cu(Ⅱ)-Fe(Ⅱ) Heterobinuclear Complexes

~The~andmagneti~Of~~areatoPicthahasndchinndinndnd.bondinthewiin-wtofbinudearCU(n)-Fe(u)-,chewedwiththe~alleq-nettrioftwnew~-,[CU(oxa)Fe(L)21sa(Lbo1,1o-~(Phen)nd5-nithe1'1o-~(NQ-Phen)),whereOxaisN,N'-bis(2-amhathy).edfor.-Synboor(1)ToCh(oxae)2(94.2mp'o.4ed)theindri(5nd)wasbo-lyadtalaedboofso.Wio(111.2mp,o.4nuno)inmeto(1ond)ndaboofPhen(144-2mp,o.8mrnO)inrne~(1OrnL)underN2atrmpe.theedfor2hthegreddebm~thuSfo~wereforoff,washededtimeswithrne~anddiethyletheranddriedoverP2QUnderededpe.ha:C,…     

Blue Luminescent Zinc(Ⅱ)- and Cadmium(Ⅱ)-1,4-phenylenediacetate Complexes

Two mixed-ligand polymeric complexes formulated as {[Zn(pda)(bpy)]·0.5H2O}n (pdathermally synthesized. Single-crystal X-ray diffraction analyses reveal that the structures of complexes 1 and 2 possess similar one-dimensional zigzag chains. Crystal data for compound 1: monoclinic, space group P21/c, a = 15.965(2), b = 8.305(1), c = 14.856(2) (A),β= 1 1 1.048(2)°, Mr = 422.73, V= 1838.2(4) A3, Z= 4, Dc = 1.528 g/cm3, μ = 1.368 mm-1, F(000) = 868, the final R = 0.0783 and wR= 0.1469 (w=1/[σ2(Fo2) + (0.035 1p)2+ 8.0014P], where P = (Fo2+ 2Fc2)/3) based on 2025 observed reflections with I ＞ 2σ(I); and those for compound 2: monoclinic, space group C2/c, a = 29.921 (7), b= 8.5400(17), c = 15.320(3) (A),β= 99.59(3)°, Mr = 487.75, V = 3859.9(14) A3, Z = 8, Dc = 1.668g/cm3, μ = 1.169 mm-1, F(000) = 1936, the final R = 0.0723 and wR = 0.1612 (w = 1/[σ32(Fo2 ) +(0.0681p)2+ 55.9577P], where P = (Fo2+ 2Fc2)/3) based on 2130 observed reflections with I ＞ 2σ(I).Fluorescent analyses show that both complexes exhibit intense blue luminescence (λmax = 485 nm for 1and 475 nm for 2) upon excitation at 330 nm.