Synthesis, x-ray structure and anion binding properties of a cryptand-like hybrid calixpyrrole

The novel cryptand in/out-3, containing two tripyrrolemethane units briged by three 1,3- diisopropylidenbenzene arms was readily synthesized by a convergent three-step synthesis. It binds fluoride by inclusion with excellent selectivity with respect to a number of other tested anions. The structure of the free receptor and that of its fluoride complex were investigated in solution by NMR spectroscopy. The solid state X-ray structure of the free cryptand 3 was also determined.

Diorganoruthenium complexes incorporating noninnocent [C6H2(CH2ER2)2-3,5]22-(E = N, P) Bis-Pincer bridging ligands: synthesis, spectroelectrochemistry, and DFT studies

The dinuclear complex [(tpy)Ru-II(PCP-PCP)Ru-II(tPY)]Cl-2 (bridging PCP-PCP = 3,3',5,5'-tetrakis(diphenylphosphinomethyl)biphenyl, [C6H2(CH2PPh2)(2)-3,5](2)(2-)) was prepared via a transcyclometalation reaction of the bis-pincer ligand [PC(H)P-PC(H)P] and the Ru(II) precursor [Ru(NCN)(tpy)]Cl (NCN = [C6H3(CH2NMe2)(2)-2,6](-)) followed by a reaction with 2,2':6',2 ''-terpyridine (tpy). Electrochemical and spectroscopic properties of [(tpy)Ru-II(PCP-PCP)Ru-II(tPY)]Cl-2 are compared with those of the closely related [(tpy)Ru-II(NCN-NCN)Ru-II(tpy)](PF6)(2) (NCN-NCN = [C6H2(CH2- NMe2)(2)-3,5](2)(2-)) obtained by two-electron reduction of [(tpy)Ru-III(NCN-NCN)Ru-III(tpy)](PF6)(4). The molecular structure of the latter complex has been determined by single-crystal X-ray structure determination. One-electron reduction of [(tpy)Ru-III(NCN-NCN)Ru-III(tpy)](PF6)(4) and one-electron oxidation of [(tpy)Ru-II(PCP-PCP)RUII(tpy)]Cl-2 yielded the mixed-valence species [(tpy)Ru-III(NCN-NCN)RUII(tpy)](3+) and [(tpy)Ru-III(PCP-PCP)RUII(tpy)](3+), respectively. The comproportionation equilibrium constants K-c (900 and 748 for [(tpy)Ru-III(NCN-NCN)Ru-III(tpy)](4+) and [(tpy)Ru-II(PCP-PCP)RUII(tpy)](2+), respectively) determined from cyclic voltammetric data reveal comparable stability of the [Ru-III-Ru-II] state of both complexes. Spectroelectrochemical measurements and near-infrared (NIR) spectroscopy were employed to further characterize the different redox states with special focus on the mixed-valence species and their NIR bands. Analysis of these bands in the framework of Hush theory indicates that the mixed-valence complexes [(tpy)Ru-III(PCP-PCP)RUII(tpy)](3+) and [(tpy)Ru-III(NCN-NCN)RUII(tpy)](3+) belong to strongly coupled borderline Class II/Class III and intrinsically coupled Class III systems, respectively. Preliminary DFT calculations suggest that extensive delocalization of the spin density over the metal centers and the bridging ligand exists. TD-DFT calculations then suggested a substantial MLCT character of the NIR electronic transitions. The results obtained in this study point to a decreased metal-metal electronic interaction accommodated by the double-cyclometalated bis-pincer bridge when strong sigma-donor NMe2 groups are replaced by weak sigma-donor, pi-acceptor PPh2 groups

Synthesis, spectroscopy and spectroelectrochemistry of chlorocarbonyl {1,2-bis[(2,6-diisopropylphenyl)imino]-acenaphthene-kappa(2)-N,N '}rhodium (I)

Reaction of the dinuclear complex [{Rh(CO)(2)}(2) (mu-Cl)(2)]with an alpha-diimine ligand, 1,2- bis[(2,6-diisopropylphenyl) imino] acenaphthene (iPr(2)Ph-bian), produces square-planar [RhCl(CO)(iPr(2)Ph-bian)]. For the first time, 2: 1 and 1: 1 alpha-diimine/dimer reactions yielded the same product. The rigidity of iPr(2)Ph-bian together with its flexible electronic properties and steric requirements of the 2,6-diisopropyl substituents on the benzene rings allow rapid closure of a chelate bond and replacement of a CO ligand instead of chloride. A resonance Raman study of [RhCl(CO)(iPr(2)Ph-bian)] has revealed a predominant Rh-to-bian charge transfer (MLCT) character of electronic transitions in the visible spectral region. The stabilisation of [RhCl(CO)(iPr(2)Ph-bian)] in lower oxidation states by the pi-acceptor iPr(2)Ph-bian ligand was investigated in situ by UV-VIS, IR and EPR spectroelectrochemistry at variable temperatures. The construction of the novel UV-VIS-NIR-IR low-temperature OTTLE cell used in these studies is described in the last part of the paper.

Coordination behavior of symmetrical hexadentate O2N2S2-donor Schiff bases toward zinc (II): synthesis, characterization, and crystal structure

Two series of zinc(II) complexes of two Schiff bases (H2L1 and H2L2) formulated as [Zn(HL1/HL2)]ClO4 (1a and 1b) and [Zn(L1/L2)] (2a and 2b), where H2L1 = 1,8-bis(salicylideneamino)-3,6-dithiaoctane and H2L2 = 1,9-bis(salicylideneamino)-3,7-dithianonane, have been prepared and isolated in pure form by changing the chemical environment. Elemental, spectral, and other physicochemical results characterize the complexes. A single crystal X-ray diffraction study confirms the structure of [Zn(HL1)]ClO4 (1a). In 1a, zinc(II) has a distorted octahedral environment with a ZnO2N2S2 chromophore.

Synthesis and biological evaluation of a polyglutamic acid-dopamine conjugate: a new antiangiogenic agent

Dopamine has previously been shown to inhibit angiogenesis in vitro and in vivo, but its clinical applications in this context are severely limited by its short half-life. Here we report the synthesis of a polyglutamic acid-dopamine conjugate and show that conjugation significantly extends (from 1 to 24 h) dopamine’s antiangiogenic activity in vitro and in vivo. These findings form the basis for the development of a new class of agents for the treatment of angiogenesis-dependent diseases.

Nickel(II) and copper(II) complexes of Schiff base ligands containing N4O2 and N4S2 donors with pyrrole terminal binding groups: synthesis, characterization, X-ray structures, DFT and electrochemical studies

A series of hexadentate ligands, H2Lm (m = 1−4), [1H-pyrrol-2-ylmethylene]{2-[2-(2-{[1H-pyrrol-2-ylmethylene]amino}phenoxy)ethoxy]phenyl}amine (H2L1), [1H-pyrrol-2-ylmethylene]{2-[4-(2-{[1H-pyrrol-2-ylmethylene]amino}phenoxy)butoxy]phenyl}amine (H2L2), [1H-pyrrol-2-ylmethylene][2-({2-[(2-{[1H-pyrrol-2-ylmethylene]amino}phenyl)thio]ethyl}thio)phenyl]amine (H2L3) and [1H-pyrrol-2-ylmethylene][2-({4-[(2-{[1H-pyrrol-2-lmethylene]amino}phenyl)thio]butyl}thio) phenyl]amine (H2L4) were prepared by condensation reaction of pyrrol-2-carboxaldehyde with {2-[2-(2-aminophenoxy)ethoxy]phenyl}amine, {2-[4-(2-aminophenoxy)butoxy]phenyl}amine, [2-({2-[(2-aminophenyl)thio]ethyl}thio)phenyl]amine and [2-({4-[(2-aminophenyl)thio]butyl}thio)phenyl]amine respectively. Reaction of these ligands with nickel(II) and copper(II) acetate gave complexes of the form MLm (m = 1−4), and the synthesized ligands and their complexes have been characterized by a variety of physico-chemical techniques. The solid and solution states investigations show that the complexes are neutral. The molecular structures of NiL3 and CuL2, which have been determined by single crystal X-ray diffraction, indicate that the NiL3 complex has a distorted octahedral coordination environment around the metal while the CuL2 complex has a seesaw coordination geometry. DFT calculations were used to analyse the electronic structure and simulation of the electronic absorption spectrum of the CuL2 complex using TDDFT gives results that are consistent with the measured spectroscopic behavior of the complex. Cyclic voltammetry indicates that all copper complexes are electrochemically inactive but the nickel complexes with softer thioethers are more easily oxidized than their oxygen analogs.

Synthesis and structure of the Mn II,II complex salt [Mn2(η1η1μ2-oda)(phen)4(H2O)2][Mn2][Mn2(η1η1μ2-oda)(phen)4(η1-oda)2].4H2O (odah2 = octanedioic acid): a catalyst for H2O2 disproportionation

The synthesis and X-ray crystal structure of the MnII,11 complex double salt [Mn2(η1η1µ2-oda)(phen)4(H2O)2][Mn2(η1η1µ2-oda(phen)4(η1-oda)2]·4H2O is reported, together with its catalytic activity towards the disproportionation of H2O2.

Synthesis of the μ-PH hexaosmium clusters [Os6H2(CO)20L(μ3-PH)](L = CO or MeCN) and their reactions with base: X-ray crystal structures of [Os6H2(CO)20(MeCN)(μ3-PH)] and [Os6H3(CO)19(CO2Me)(μ3-PH)]

Mild heating of the phosphidotriosmium cluster [Os3H(CO)10(µ2-PH2)](1) with [Os3(CO)12 –n(MeCN)n](n= 1 or 2) gives high yields of the (µ3-PH) bridged hexaosmium clusters (2) and (3); reactions of (2) and (3) with bases and X-ray structure analyses of (3) and of (6), which was obtained from (3) and MeO– followed by acid treatment are described.

Synthesis, properties, and X-ray crystal and molecular structures of homoleptic alkenyls of tin and chromium

Reaction of Li(CPhCMe2) with SnCl4 or CrCl3·3thf (thf = tetrahydrofuran) affords the isoleptic compounds Sn(CPhCMe2)4 or [Cr(CPhCMe2)4] respectively. The mode of formation and chemical properties are reported for the chromium species, and the structures of the new compounds, both of which have been determined by single-crystal X-ray analysis, are described.

Synthesis and X-ray crystal and molecular structure of tetrakis(2,2-dimethyl-1-phenylethenyl)chromium(IV), the first structurally-characterised homoleptic alkenyl compound of a transition metal

The title compound, the first homoleptic Group 6A metal alkenyl, has been prepared from CrCl3·3(thf), and its properties, including X-ray crystal structure determination, are reported.

Unsaturated σ-hydrocarbyl transition-metal complexes. Part 2. Synthesis and reactions of vinylplatinum complexes and a comparison with analogous fluorovinyl and alkynyl complexes

Alkenyl (CHCH2 or CFCF2) or alkynyl (CCPh) derivatives of trimethyltin are shown to be superior to lithium or magnesium reagents for the synthesis of corresponding mono-organoplatinum(II) species by metathesis (L = SnMe3R +cis-[PtCl2L2]→trans-[PtRClL2]+ SnMe3Cl tertiary phosphine). The reactivity order for SnMe3R is R = CCPh > CFCF2 > CHCH2. This order is also found for oxidative addition of SnMe3R to Pt0 to give cis-[PtRL2(SnMe3)]. When the latter complex (R = CHCH2) reacts with X2 or MeX further oxidative addition occurs exclusively at the platinum centre. Aromatic isonitriles (R′NC)co-ordinate to the platinum and give insertion products trans-[Pt{C(CHCH2)= NR′}ClL2] on heating or carbene complexes with NBunH2. The alkynyl trans-[Pt(CCPh)ClL2] also forms 1 :1 adducts with R′NC and carbene complexes therefrom, but no insertion products. Spectroscopic data for the new complexes are presented.

Sterically hindered metal alkenyls. Part 1. Synthesis, reactions, and crystal and molecular structures of some palladium and platinum σ-alkenyls

The compounds trans-[PtBr{C(C10H15)CH2}(PEt3)2](1)(C10H15= adamant-1-yl), trans-[MBr{C(C10H7)CMe2}(PEt3)2][M = Pd (2) or Pt (3); C10H7= naphth-1-yl], and trans-[MBr{C(Ph)CMe2}(PEt3)2][M = Pd (4) or Pt (5)] have been prepared from Grignard [for (2) and (3)] or lithium reagents [for (1), (4), and (5)] and appropriate dichlorobis(phosphine)metal derivatives. Full single-crystal X-ray data are reported for (1) and (3), and reveal unusually long Pt–C(sp2) bonds. Insertion reactions into these M–C bonds occur with MeNC [for (1), (3), and (5)], and with CO [for (1) and (3)]; the latter, the first reported insertion into a Pt–C(sp2) bond, occurs under mild conditions as expected for the abnormally long M–C bonds.