Download or read book Synthesis and Characterization of Bipyridylosmium II Mixed Metal Complexes with Dipyrido 2 3 a 2 3 h phenazine DPOP Bridging Ligand written by Sunita Dayal and published by . This book was released on 1997 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Bipyridylruthenium II Complexes Bound to the Bridging Ligand Dipyrido 2 3 a 2 3 h phenazine dpop and Tetraammineruthenium II Complexes Bound to the Bridging Ligand 3 6 bis 2 pyridyl 1 2 4 5 tetrazine bptz written by Jane E. B. Johnson and published by . This book was released on 1993 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Tetrathiafulvalene and 2 2 Bipyridine written by Roger Gumbau-Brisa and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Bifunctional Metal Complexes written by and published by . This book was released on 2015 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this research project was to synthesize and characterize different bifunctional metal complexes possessing bipyridine (bipy) ligands substituted with two amino groups at the 6, 6' positions. The goal was to create catalysts with better performance by the addition of pendant basic amino groups. Three similar bipyridine ligands were synthesized: 6,6'-diamino-2,2'-bipyridine (A), N6, N6'-dimethyl-6,6'-diamino-2,2'- bipyridine (B), and N6, N6, N6', N6'-tetramethyl-6,6'-diamino-2,2'-bipyridine (C). Using these ligands, three sets of metal complexes were synthesized. The first set was [Ru(terpy)(bipy*)Cl]Cl complexes, where bipy* represents ligands A and B, which were characterized and tested in water oxidation reactions. The results indicated that both Ru complexes showed catalytic activities, but comparison with the parent 2,2'-bipyridine analog showed that the amino derivatives were not better as hoped. The second set of metal complexes were RuCp(bipy*)(CH3CN)PF6. All three ligands were successfully coordinated to the CpRu(CH3CN)+ fragment and the metal complexes were characterized using NMR and elemental analysis. The last set of metal complexes were [IrCp*(bipy*)Cl]Cl. Only ligands A and B could be coordinated and the two metal complexes were characterized. Although the three ligands have similar structure, basicity, and electronic properties, A and B were much easier to coordinate to metals than C, most likely because of less steric hindrance to metal binding at the pyridine nitrogens.
Download or read book Synthesis Characterization and Reactivity Studies of Low coordinate Late Transition Metal Complexes and the Preparation and Characterization of a Low coordinate Samarium Complex written by Pei Zhao and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation focuses on the synthesis, characterization and reactivity study of terphenyl ligand stabilized bis([mu]-oxo) dimeric iron and cobalt complexes. The synthesis and characterization of low-coordinate cobalt alkyl and iron alkyl complexes are also described. In addition, it describes the preparation of the first monomeric homoleptic solvent-free bis(aryloxide) lanthanide complex. The solid state structures of new compounds were determined by single crystal X-ray crystallography. Magnetic properties of paramagnetic compounds were measured by superconducting quantum interference device (SQUID) or Evans' methods for solid state or solution phase, respectively. The new compounds were also characterized by UV-Visible spectroscopy. Furthermore, infrared spectroscopy, Mössbauer spectroscopy, electron paramagnetic resonance spectroscopy, mass spectrometry, cyclic voltammetry and elemental analysis were employed to characterize some of the compounds when applicable. In some cases, DFT calculations were applied to elucidate the bonding and energy levels of molecular orbitals in the complexes. In Chapter 2, The bis([mu]-oxo) dimeric complexes {Ar[superscript iPr8]OM([mu]-O)}2 (Ar [superscript iPr8] = -C6H-2,6-(C6H2-2,4,6-[superscript i]Pr3)2-3,5-[superscript i]Pr2; M = Fe or Co) were prepared by oxidation of the metal (I) half-sandwich complexes {Ar[superscript iPr8]M([eta]6-arene)} (arene = benzene or toluene; M = Fe or Co). The iron species {Ar[superscript iPr8]OFe([mu]-O)}2 was prepared by reacting {Ar[superscript iPr8]Fe([eta]6-benzene)} with N2O or O2 and the cobalt species {Ar[superscript iPr8]OCo([mu]-O)}2 was prepared by reacting {Ar[superscript iPr8]Co([eta]6-toluene)} with O2. Both {Ar[superscript iPr8]OFe([mu]-O)}2 and {Ar[superscript iPr8]OCo([mu]-O)}2 were characterized by X-ray crystallography, UV-vis spectroscopy, magnetic measurements and, in the case of the iron species, by Mössbauer spectroscopy. The solid-state structures of both compounds reveal unique M2([mu]-O)2 (M = Fe or Co) cores with formally three-coordinate metal ions. The Fe···Fe separation in {Ar[superscript iPr8]OFe([mu]-O)}2 bears a resemblance to that in the Fe2([mu]-O)2 diamond core proposed for the methane monooxygenase intermediate Q. The structural differences between {Ar[superscript iPr8]OFe([mu]-O)}2 and {Ar[superscript iPr8]OCo([mu]-O)}2 are reflected in rather differing magnetic behavior. Compound {Ar[superscript iPr8]OCo([mu]-O)}2 is thermally unstable and its decomposition at room temperature resulted in the oxidation of the Ar[superscript iPr8] ligand via oxygen insertion and addition to the central aryl ring of the terphenyl ligand to produce the 5,5'-peroxy-bis[4,6-[superscript i]Pr2-3,7-bis(2,4,6-iPr3-phenyl)oxepin-2(5H)-one]. The structure of the oxidized terphenyl species is closely related to that of a key intermediate proposed for the oxidation of benzene. In Chapter 3, the homoleptic, cobalt(I) alkyl [Co{C(SiMe2Ph)3}]2 was prepared by reacting CoCl2 with [Li{C(SiMe2Ph)3}(THF)] in a 1:2 ratio though the initial intent was to synthesize a dialkyl cobalt (II) complex. Attempts to synthesize the corresponding iron(I) species led to the iron(II) salt [Li(THF)4][Fe2([mu]-Cl)3{C(SiMe2Ph)3}2]. Both complexes were characterized by X-ray crystallography, UV-vis spectroscopy, and magnetic measurements. The structure of [Co{C(SiMe2Ph)3}]2 consists of dimeric units in which each cobalt(I) ion is [sigma]-bonded to the central carbon of the alkyl group -C(SiMe2Ph)3 and [pi]-bonded to one of the phenyl rings of the -C(SiMe2Ph)3 ligand attached to the other cobalt(I) ion in the dimer. The structure of [Li(THF)4][Fe2([mu]-Cl)3{C(SiMe2Ph)3}2] features three chlorides bridging two iron(II) ions. Each iron (II) ion is also [sigma]-bonded to the central carbon of a terminal -C(SiMe2Ph)3 anionic ligand. The magnetic properties of [Co{C(SiMe2Ph)3}]2 reveal the presence of two independent cobalt (I) ions with S = 1 and a significant zero-field splitting of D = 38.0(2) cm−1. The magnetic properties of [Li(THF)4][Fe2([mu]-Cl)3{C(SiMe2Ph)3}2] reveal extensive antiferromagnetic exchange coupling with J = -149(4) cm−1 and a large second-order Zeeman contribution to its molar magnetic susceptibility. Formation of the alkyl [Co{C(SiMe2Ph)3}]2 and the halide complex [Li(THF)4][Fe2([mu]-Cl)3{C(SiMe2Ph)3}2] under similar conditions is probably due to the fact that Co(II) is more readily reduced than Fe(II). Some other synthetic routes were also attempted to synthesize a dialkyl cobalt (II) complex and they are described in this chapter. Neither [Co(NPh2)2]2 nor cobaltocene reacts with [Li{C(SiMe2Ph)3}(THF)] to afford a dialkyl cobalt (II) complex. Metathesis reactions of cobalt halides with lithium salts of alkyl ligand HCPh2R (R = -Ph or -SiMe3) resulted in the reduction of cobalt (II) to cobalt metal and the coupling of ligands, which indicate that homolytic cleavage of the cobalt-carbon bond was probably involved in the metathesis reactions. Furthermore, in chapter 4, reaction of Sm[N(SiMe3)2]2(THF)2 with two equivalents of bulky aryloxide ligand HOAr[superscript iPr6] (Ar[superscript iPr6] = -C6H3-2,6-(C6H2-2,4,6-[superscript i]Pr3)2) afforded the first monomeric homoleptic solvent-free bis(aryloxide) lanthanide complex Sm(OAr[superscript iPr6])2. The complex was characterized by crystallography, UV-Visible spectrum, IR and magnetically by the Evans' method. The O-Sm-O angle is bent at 111.08(9)̊. The samarium ion in Sm(OAr[superscript iPr6])2 also shows weak interactions with the flanking aryl rings of the terphenyloxide ligands. The complex is paramagnetic at room temperature with magnetic moment of 3.51 [mu]B.
Download or read book Rational Design Synthesis and Characterization of Amide Functionalized Pyridine and Benzimidazole Transition Metal Complexes written by Samuel S. K. Asem and published by . This book was released on 2011 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study expands our efforts to make a new class of Pt (II) compounds analogous to cisplatin and its derivatives using sterically hindered ligands. Pt compounds in this series have been synthesized using specially designed pyridine and benzimidazole ligands. These heterocycles, amide functionalized at position 2 with aryl and alkyl pendants, rapidly change their mode of coordination depending on the pH of the medium. These ligands, synthesized using condensation chemistry, also coordinate to Co(II), Ni(H), Cu(lI), and Zn(1I) generally as anionic bis-chelates through the benzimidazole nitrogen and the carbonyl oxygen, creating a four-coordinate complex with the exception of an unusual trigonal bipyramidal Zn(H) complex. I H NMR temperature studies reveal that these ligands interconvert between imide and amide isomers and that electron withdrawing pendants favor amide isomers. Crystal structures of Co(II) and Ni(1I) complexes of N-( I-methylbenzimidazol-2-yl)cyclohexanecarboxamide, for example, show two ligands bind per metal ion when reacted with acetate and nitrate salts. The bischelates of these Ni(1I) complexes also show expansions of their coordination spheres from four to five-coordinate. Furthermore, these Ni(II) bis-chelated complexes possess square planar or distorted 4-coordinate geometries. The synthesis and properties of several new Pt (II) complexes containing these ligands will be presented. A second generation and novel complex class containing metal-binding, linker and recognition domains is reported. Both classes of Pt complexes were obtained using a synthetic methodology which favors the cis isomers. The second generation complex crystallizes in the monoclinic space group P2dn with lattice dimensions a = 17.7393(5) A, b = 11.4632(3) A, c = 19.3959(5) A and ~ = 99.794(3)°. These complexes have been characterized using physical methods that include X-ray crystallography, IH &13C NMR, Mass spectrometry, UV and IR spectroscopies. Complexes similar in structure to cisplatin and carboplatin show varying cytotoxic properties toward different cancer cell lines. Additionally, some of these new Pt complexes show comparable and promising cytotoxicity against prostate cancer cell lines.
Download or read book Design Synthesis and Reactivity of Bimetallic Complexes of Dimethylplatinum II Containing Ditopic Ligands written by Matthew S. McCready and published by . This book was released on 2015 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes a study of monometallic and bimetallic dimethylplatinum(II) complexes containing ditopic nitrogen donor ligands. This work details the design and synthesis of side-to-side and cofacial arranged ligands and their respective coordination chemistry. The study of the synthesis, characterization and reaction mechanisms of the various dimethylplatinum(II) complexes is outlined in detail with special emphasis focused on the reactivity of the complexes towards oxidative addition. The ditopic ligand 6-dppd, 1,4-di(2-pyridyl)-5,6,7,8,9,10- hexahydrocycloocta[d]pyridazine, was observed to coordinate only a single equivalent of a platinum(II) center. The inability to coordinate a second equivalent, even through an assisted bridging atom, is presumed to be due to a steric clash between the free pyridyl group and the cyclooctyl backbone. In attempts to make heterobimetallic complexes of 6-dppd, the complex [PtMe2(6-dppd)] was observed to react preferentially with mercuric halides by oxidative addition rather than coordination of the mercuric salt in the second coordination site giving complexes [PtXMe2(HgX)(6-dppd)] where X = Br, Cl, OAc. This indicates that the platinum center is actually a better nucleophile than the free pyridyl nitrogen atom. The oxidative addition of solvent dichloromethane was also observed showing the enhancedreactivity of [PtMe2(6-dppd)]. Finally, [PtMe2(6-dppd)] was treated with DCl at low temperature to give the deuteridoplatinum(IV) complex. The deuteridoplatinum(IV) complex reductively eliminates methane in solution and extensive H/D exchange occurs into the CH4 product at low temperature indicating very easy reversibility of the exchange between hydridomethylplatinum(IV) and methaneplatinum(II) complexes. The abstraction of a chloride ligand from [PtClMe(6-dppd)] led to the formation of a complex dimer structure endo, endo-[Pt2Me2(?2-?3-6-dppd)2][OTf]2. This process allowed for the formation of a bimetallic platinum(II) complex which retained the initial stereochemistry. The protonolysis of [PtMe2(6-dppd)] with one equivalent of HOTf led to the generation of methane gas and the concomitant formation of both endo, endo-[Pt2Me2(?2-?3-6-dppd)2][OTf]2 and exo, exo-[Pt2Me2(?2-?3-6-dppd)2][OTf]2. The structures of the exo isomeric clamshell dimers appeared much less sterically hindered in the solid state and were observed experimentally and computationally to be the thermodynamically preferred isomers. The mechanism, selectivity and reversibility of this isomerism process was explored in detail. The reactions of [PtMe2(6-dppd)] with alkyl bromides RCH2Br, which possess hydrogen bonding functionality, result in the formation of stable organoplatinum(IV) complexes capable of forming supramolecular structure via hydrogen bonding. Both intra and inter molecular hydrogen bonding is observed in the formation of supramolecular architectures which self-assemble in the solid state through additional?-stacking and weak secondary interactions. The new anthracene derived ditopic ligands, bpad = N1,N8-bis(pyridin-2- ylmethylene)anthracene-1,8-diamine and adpa = (N, N)-4,4'-(anthracene-1,8-diylbis(ethyne- 2,1-diyl))-bis(N-(pyridin-2-ylmethylene)aniline) were prepared, characterized and used to coordinate dimethylplatinum(II) centers giving cofacial bimetallic complexes of dimethylplatinum(II). [Pt2Me4(bpad)] was shown to degrade over time in solution through a proposed metalation event involving the anthracene backbone. The oxidative addition of a variety of substrates was performed using [Pt2Me4(adpa)] giving stable diplatinum(IV) complexes as characterized by 1H NMR spectroscopy. The new xanthene derived ditopic ligands, ppxda = 2,7-di-tert-butyl-9,9-dimethyl-N4,N5-bis(4-(pyridin-2- ylmethyleneamino)phenyl)-xanthene-4,5-dicarboxamide and pmxda = 2,7-di-tert-butyl-9,9- dimethyl-bis(pyridine-2-ylmethylene)-9H-xanthene-4,5-diamine were prepared characterized and used to ligate two equivalents of a dimethylplatinum(II) center. Diplatinum complexes of both ligands were shown to easily undergo oxidative addition to give the corresponding diplatinum(IV) complexes which adopt the anti orientation. The syn alignment of metal centers was accessible through the abstraction of halides ligands and incorporation of bridging groups as is the case for the pyrazine bridged bimetallic platinum complex [Pt2Me6(C4H4N2)(pmxda)][OSO2CF3]2.
Download or read book Synthesis and Characterization of 2 2 pyridil Mono and Dihydrazone and Molybdenum Metal Complexes written by Debtanu Basu and published by . This book was released on 1995 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of 3d Metal Complexes with the Mono N Oxides of 2 2 Bipyridine and 1 10 Phenanthroline written by Anthony Nicholas Speca and published by . This book was released on 1973 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Spectroscopic Characterisation of Bis bis Bipyridine ruthenium II 3 3 4 4 Tetraiminobiphenyl and Its Redox Products written by P. R. Auburn and published by . This book was released on 1990 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tetraiminobiphenyl forms a redox series of binuclear complexes obtained by coordinating the Ru(bpy)2 (bpy = 2, 2 - bipyridine) fragment at each end of the molecule. The ligand is capable of existing in six redox states, and three of these, including a mixed valence species, are characterised as their bis(Ru(bpy)2) complexes. Electrochemical, electron spin resonance and optical data are presented. These are discussed in terms of localisation and delocalisation of the ruthenium to ligand charge transfer states as a function of redox level. The mixed valence species displays an intervalence (ligand to ligand) charge transfer band, and the degree of electronic coupling is shown to be relatively large. There is some evidence that the biphenyl twist angle changes with oxidation state suggesting that these complexes might be useful building blocks for molecular wires and switches. Keywords: Biphenyl, Ruthenium, Redox, Bipyridine. (JES).
Download or read book Synthesis and Characterization of Benzo 2 1 3 thiadiazole Derivatives and Their Metal Complexes written by Saturday Amedu Okeh and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
