Different Coordination Environments (different + coordination_environment)

Distribution by Scientific Domains

Selected Abstracts

Synthesis and Structure of Trialkyltantalum Complexes Stabilized by Aminopyridinato Ligands

Awal Noor
Abstract (4-Methylpyridin-2-yl)(trimethylsilyl)amine (1), (6-methylpyridin-2-yl)(trimethylsilyl)amine (2), and (2,6-diisopropylphenyl)(pyridin-2-yl)amine (3) were deprotonated and used as ligands to synthesize trialkyltantalum complexes. The reaction of 2 equiv. of 1 or 2 with pentabenzyltantalum afforded tribenzyltantalum(V) complexes by toluene elimination. Analogous reaction using 3 failed. Lithiation of 3 followed by the reaction with tribenzyltantalum dichloride gave rise to the corresponding tribenzyl complex. Other alkyltantalum complexes stabilized by this ligand environment can be prepared by treating tantalum pentachloride with 2 equiv. oflithiated 3 to form a bis(aminopyridinato)tantalum trichloride. The reaction of this trichloride with 3 equiv. of alkyllithium compounds like methyllithium affords the corresponding trialkyltantalum complexes. X-ray diffraction studies of four of the synthesized complexes were carried out. They adopt two different coordination environments, either slightly distorted capped octahedrons (sterically less demanding aminopyridinato ligands) or pentagonal bipyramids (bulkier aminopyridinato ligands). The alkyl species were surprisingly stable at elevated temperatures and no formation of mixed alkyl/alkylidene complexes was observed. Alkyl cation formation and the behaviour of a selection of these compounds in olefin polymerization were explored. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Poly[bis(,2 -2-aminopyrazine-,2N1:N4)(,2 -nitrato-,2O:O)(nitrato-,2O,O,)disilver(I)]: an achiral two-dimensional coordination polymer forming chiral crystals

Di Sun
The solution reaction of AgNO3 and 2-aminopyrazine (apyz) in a 1:1 ratio gives rise to the title compound, [Ag2(NO3)2(C4H5N3)2]n, (I), which possesses a chiral crystal structure. In (I), both of the crystallographically independent AgI cations are coordinated in tetrahedral geometries by two N atoms from two apyz ligands and two O atoms from nitrate anions; however, the AgI centers show two different coordination environments in which one is coordinated by two O atoms from two different symmetry-related nitrate anions and the second is coordinated by two O atoms from a single nitrate anion. The crystal structure consists of one-dimensional AgI,apyz chains, which are further extended by ,2 -,2O:O nitrate anions into a two-dimensional (4,4) sheet. N,H...O and Capyz,H...O hydrogen bonds connect neighboring sheets to form a three-dimensional supramolecular framework. [source]

A novel parallel interpenetrating two-dimensional (4,4) network: poly[[,2 -1,4-bis(imidazol-1-ylmethyl)benzene](,2 -naphthalene-1,4-dicarboxylato)zinc(II)]

Ya-Ping Li
In the title coordination compound, [Zn(C12H6O4)(C14H14N4)]n, the two ZnII centers exhibit different coordination environments. One ZnII center is four-coordinated in a distorted tetrahedral environment surrounded by two carboxylate O atoms from two different naphthalene-1,4-dicarboxylate (1,4-ndc) anions and two N atoms from two distinct 1,4-bis(imidazol-1-ylmethyl)benzene (1,4-bix) ligands. The coordination of the second ZnII center comprises two N atoms from two different 1,4-bix ligands and three carboxylate O atoms from two different 1,4-ndc ligands in a highly distorted square-pyramidal environment. The 1,4-bix ligand and the 1,4-ndc anion link adjacent ZnII centers into a two-dimensional four-connected (4,4) network. The two (4,4) networks are interpenetrated in a parallel mode. [source]

Poly[[di-,-aqua-tetraaquadi-,-hydroxido-bis(,3 -3-nitrophthalato)tricopper(II)] dihydrate]

Feng-Qin Wang
The novel title complex, {[Cu3(C8H3NO6)2(OH)2(H2O)6]2H2O}n, has a one-dimensional polymeric double chain structure where the three Cu atoms are linked by ,2 -OH and ,2 -H2O groups, and these trinuclear centres are bridged by two 3-nitrophthalate ligands. The asymmetric unit contains one and a half crystallographically independent Cu atoms (one lying on a centre of inversion), both coordinated by six O atoms and exhibiting distorted octahedral coordination geometries, but with different coordination environments. Each 3-nitrophthalate ligand connects to three Cu atoms through two O atoms of one carboxylate group and one O atom of the nitro group. The remaining carboxylate group is free and is involved in intrachain hydrogen bonds, reinforcing the chain linkage. [source]

Synchrotron X-ray study of noncentrosymmetric Tb3RuO7 with partial structural disorder

Nobuo Ishizawa
Single-crystal synchrotron X-ray diffraction reveals partial structural disorder of Tb atoms at 293,K in flux-grown Tb3RuO7 (triterbium ruthenium heptaoxide) crystals. The structure is noncentrosymmetric and composed of infinite single chains of corner-linked RuO6 octahedra embedded in a Tb3O matrix. Two Tb atom sites out of the six crystallographically independent Tb sites are split into two positions. The split sites are separated by approximately 0.3,0.4,, with slightly different coordination environments. The RuO6 octahedra in the present P21nb modification have two tilt systems about the a and c axes, in contrast with a single tilt about c in the other Cmcm modifications of Ln3RuO7 (Ln = lanthanoid elements). [source]

Synthesis, Crystal Structures, and Properties of Oxovanadium(IV),Lanthanide(III) Heteronuclear Complexes

Wei Shi
Abstract A new series of oxovanadium(IV),lanthanide(III) heteronuclear complexes [Yb(H2O)8]2[(VO)2(TTHA)]3,21,H2O (1), {[Ho(H2O)7(VO)2(TTHA)][(VO)2(TTHA)]0.5}, 8.5,H2O (2), {[Gd(H2O)7(VO)2(TTHA)][(VO)2(TTHA)]0.5},8.5,H2O (3), {[Eu(H2O)7][(VO)2(TTHA)]1.5}, 10.5,H2O (4), and [Pr2(H2O)6(SO4)2][(VO)2(TTHA)] (5) (H6TTHA=triethylenetetraaminehexaacetic acid) were prepared by using the bulky flexible organic acid H6TTHA as structure-directing agent. X-ray crystallographic studies reveal that they contain the same [(VO)2(TTHA)]2, unit as building block, but the Ln3+ ion lies in different coordination environments. Although the lanthanide ions always exhibit similar chemical behavior, the structures of the complexes are not homologous. Compound 1 is composed of a [Yb(H2O)8]3+ ion and a [(VO)2(TTHA)]2, ion. Compounds 2 and 3 are isomorphous; both contain a trinuclear [Ln(H2O)7(VO)2(TTHA)]+ (Ln=Ho for 2 and Gd for 3) ion and a [(VO)2(TTHA)]2, ion. Compound 4 is an extended one-dimensional chain, in which each Eu3+ ion links two [(VO)2(TTHA)]2, ions. For 5, the structure is further assembled into a three-dimensional network with an interesting framework topology comprising V2Pr2 and V4Pr2 heterometallic lattices. Moreover, 4 and 5 are the first oxovanadium(IV),lanthanide(III) coordination polymers and thus enlarge the realm of 3d,4f complexes. The IR, UV/Vis, and EPR spectra and the magnetic properties of the heterometallic complexes were studied. Notably, 2 shows unusual ferromagnetic interactions between the VO2+ and Ho3+ ions. [source]