Search results for "Denticity"
showing 10 items of 376 documents
Comprehensive Uranium Thiophosphate Chemistry: Framework Compounds Based on Pseudotetrahedrally Coordinated Central Metal Atoms
2013
The new ternary compounds UP2S6, UP2S7, U(P2S6)2, and U3(PS4)4 were prepared from uranium metal, phosphorus pentasulfide, and sulfur at 700 °C. The crystal structures were determined by single-crystal X-ray diffraction methods. UP2S6 (I) crystallizes in the ZrP2S6 structure type [tetragonal, P42/m, a = 6.8058(7) A, c = 9.7597(14) A, Z = 2], which consists of central uranium(IV) atoms coordinated by P2S64– anions (staggered conformation). The anions are two-dimensional connectors for four uranium cations arranged in one plane. The structure of UP2S7 (II) [orthorhombic, Fddd, a = 8.9966(15) A, b = 15.2869(2) A, c = 30.3195(5) A, Z = 16] is closely related to the monoclinic ZrP2S7 structure ty…
η⇌μ exchange bonding mode of bidentate tmeda ligand. Molecular structure of [Y(tmhd)3]2(μ-tmeda)
2003
Abstract The reaction between the yttrium β-diketonate complexes Y(tmhd)3(H2O)x (x=0 or 1) and 0.5 or 1 equivalent of N,N,N′,N′-tetramethylethylenediamine (tmeda=Me2NCH2CH2NMe2) in hexane at room temperature afforded [Y(tmhd)3]2(tmeda) (1) and Y(tmhd)3(tmeda) (2) derivatives, respectively. They have been characterized by FT-IR, 1H NMR spectroscopy and by single crystal X-ray diffraction for 1. Variable temperature 1H NMR experiments indicated an equilibrium between 1 and 2. Their thermal behaviors were characterized by TGA and sublimation experiments. 2 is converted into compound 1 by heating over 100 °C. These precursors were used for the growth of Y2O3 and YBa2Cu3O7 − x films by pulsed in…
Ligand dynamics of tert-butyl isocyanide oxido complexes of molybdenum(IV).
2014
The six-coordinate molybdenum(IV) oxido isocyanide complex 1 [Δ,Λ-OC-6-2-3-[MoO(N(p)∩N(i))2(CN(t)Bu)]; N(p)∩N(i) = 4-tert-butylphenyl(pyrrolato-2-ylmethylene)amine] is obtained in diastereomerically pure form in the solid state, as revealed by single-crystal X-ray diffraction. In solution, this stereoisomer equilibrates with the Δ,Λ-OC-6-2-4 diastereomer 2 at ambient temperature. The stereochemistry of both isomers has been elucidated by NMR, IR, and UV/vis spectroscopy in combination with density functional theory (DFT)/polarizable continuum model and time-dependent DFT calculations. The isomerization 1 → 2 is suggested to proceed via a dissociative trigonal twist with dissociation of the …
ChemInform Abstract: New Concepts in Multidentate Ligand Chemistry: Effects of Multidentarity on Catalytic and Spectroscopic Properties of Ferrocenyl…
2008
This tutorial review devoted to ligand chemistry deals with the design and properties of ferrocenyl polyphosphines, an original class of multidentate ligands. The development of a varied library of ferrocenyl tetra-, tri- and diphosphine ligands is reviewed. The multidentate nature of these species has led to unique spectroscopic and catalytic properties, in which the spatial proximity of phosphorus atoms is crucial. Regarding their catalytic applications, the key issues of catalyst longevity and ultralow catalyst loadings are discussed. Another part is concerned with fundamental advances gained in physical chemistry for structure elucidation by the study of the intriguing “through-space” N…
Unconventional Fluorescence Quenching in Naphthalimide-Capped CdSe/ZnS Nanoparticles
2013
Core–shell (CS) CdSe/ZnS quantum dots (QD) capped with ligands that possess a mercapto or an amino group and a naphthalimide (NI) as chromophore unit, linked by a short ethylene chain (CS@S–NI and CS@H2N–NI, respectively), have been synthesized and fully characterized by infrared and nuclear magnetic resonance spectroscopies, high-resolution transmission electron microscopy, and voltammetry as well as by steady-state absorption and emission spectroscopies. The organic ligands HS–NI and H2N–NI act as bidentate ligands, thereby causing a drastic decrease in the QD emission. This was particularly evident in the case of CS@S–NI. This behavior has been compared with that of commercially availabl…
Titanium Complexes with a Linked Amido−Cyclopentadienyl Ligand and a Bidentate Organyl Group: Synthesis, Structure, and Ethene Polymerization Activity
1998
Titanium complexes containing a linked isopropyl- or benzylamido(tetramethylcyclopentadienyl) ligand C5Me4SiMe2NR (R = iPr, CH2Ph,) and one bidentate organyl group C6H4(CH2NMe2)-2, CH2C6H4(NMe2)-2, and {η5-C5H3(CH2NMe2)-2}Fe(η5-C5H5) were prepared by salt metathesis of the corresponding dichloro complex Ti(η5:η1-C5Me4SiMe2NR)Cl2 with the lithium organyl. Single crystal X-ray structural analysis of Ti(η5:η1-C5Me4SiMe2NCH2Ph)- {C6H4(CH2NMe2)-2}Cl and of Ti(η5:η1-C5Me4SiMe2NiPr){CH2C6H4(NMe2)-2}Cl revealed the presence of intramolecular coordination with square pyramidal geometry around titanium. In the ferrocenyl derivative Ti(η5:η1-C5Me4SiMe2NCH2Ph)[{η5-C5H3(CH2NMe2)-2}Fe(η5-C5H5)]Cl the NMe…
Insertion of isocyanides into the 2-one-1-propyl—palladium(II) bond: A convenient synthetic route to C1-palladated 1-amino-3-one-1-butene compounds
1984
Abstract Migratory insertion of isocyanides CNR (R = p -C 6 H 4 OMe, Me) into the palladium—carbon σ bond of trans -[PdCl(CH 2 COMe)(PPh 3 ) 2 ] (I) yields the 1-amino-3-one-1-butenyl complexes trans -[PdCl{C(NHR)CHCOMe}(PPh 3 ) 2 ] (IIa, R = p -C 6 H 4 OMe; IIb, R = Me), which have been characterized by IR, 1 H and 31 P NMR spectra. The reaction of IIa with nickel acetate gives a diamagnetic bischelate complex of the type [Ni(ON) 2 ] , in which the deprotonated 1-amino-3-one-1-butenyl moiety acts as a bidentate O,N ligand.
Synthesis of orthometallated rhodium(III) compounds. Crystal structures of [RhCl2{η2(C6H4)PPh2}(η2-dppm)] and [RhCl{η2(C6H4)PPh2}(η1-PCCl)(phen)] (…
1993
Abstract Neutral and cationic rhodium(III) metallated compounds containing a four-membered ring are prepared by different synthetic methods: (i) from rhodium(I) compounds that contain the ligand P( o -ClC 6 H 4 )PPh 2 , by 2c-2e intramolecular oxidative addition; (ii) from metallated dirhodium(II) compounds; (iii) by ligand substitution in [RhCl 2 {η 2 -(C 6 H 4 )PPh 2 }{η 2 -P( o -ClC 6 H 4 )Ph 2 }]. The crystal structures of [RhCl 2 {η 2 -(C 6 H 4 )PPh 2 }(η 2 -dppm)] ( 2 ) and of the dichloromethane solvate of [RhCl{η 2 -(C 6 H 4 )PPh 2 }{η 1 -P( o -ClC 6 H 4 )Ph 2 }(phen)](SbF 6 ) ( 11 ) have been determined by X-ray diffraction methods. In both complexes the Rh atom is in the distorted…
Synthesis, crystal structure and magnetic properties of novel heterobimetallic malonate-bridged MIIReIV complexes (M = Mn, Fe, Co and Ni).
2008
Five novel ReIV-MII bimetallic complexes of formula [ReCl4(mu-mal)M(dmphen)2].MeCN [M = Co (1), Fe (2) and Ni (3)], [ReCl4(mu-mal)Ni(dmphen)(MeCN)2(H2O)].(MeCN)0.5(H2O)0.5 (4), and [ReCl4(mu-mal)Mn(dmphen)(H2O)2].dmphen.MeCN.H2O (5) (mal = malonate dianion, dmphen = 2,9-dimethyl-1,10-phenanthroline) have been synthesized, and the structures of 1, 2, 4, and 5 determined by single-crystal X-ray diffraction. The structures of 1 and 2 consist of neutral [ReCl4(mu-mal)M(dmphen)2] dinuclear units where the metal ions are linked through a malonate ligand which adopts simultaneously the bidentate (at ReIV) and monodentate (at MII) coordination modes. The bridging carboxylate-malonate group in them …
(2-Chlorobenzyl)tris(2-pyridinethiolato)tin(IV).
2000
In the title compound, (2-chlorobenzyl)tris(pyridine-2-thiolato)-kappa(2)N,S;kappa2N,S;kappaS-tin(IV), [Sn(C7H6Cl)(C5H4NS)3], two of the three pyridine-2-thiolato ligands (SPy) are bidentate and one is monodentate. The bonding C atom of the 2-chlorobenzyl group, the S atom of the monodentate SPy and the S and N atoms of the two bidentate SPy ligands form a distorted octahedron around the Sn atom. The three S atoms and the N atom of one of the bidentate SPy ligands occupy the equatorial positions, while the N atom of the second bidentate SPy ligand and the C(CH2) atom are axial. The axial N-Sn-C angle of 157.9 (1) degree demonstrates the heavy distortion of the octahedron.