Pentacoordinate Structure Research Articles

Antibiotics as Ligands coordinating behaviour of the cycloserine towards cobalt(II), nickel(II), zinc(II), cadmium(II), and mercury(II) Halides

AbstractThe complexes of cycloserine, 4‐amino‐3‐isoxazolidone, (Ccs) with cobalt(II), nickel(II), zinc(II), cadmium(II), and mercury(II) halides have been synthetized. Their structures have been assigned on the basis of analytical, conductivity, spectral (visible, i.r. and far‐i.r.) and magnetic data. The ligand behaves as monodentate O‐bonded. The position and multiplicity of the metal‐halide stretching frequencies are discussed and used as a guide to the stereochemistry. The most convincing structural evidence for the cobalt derivatives is a predominantly planar environment for the chloro‐complex with terminal ligands and terminal halides, while for the 1:3 complexes we could suggest a pentacoordinate structure with terminal both ligands and halides. The nickel(II) chloro‐ and bromo‐derivatives seem to have a pseudo‐tetrahedral symmetry, while the iodo‐complex resulted pentacoordinate. Both the cobalt(II) and nickel(II) derivatives resulted high spin, with the exception of Co(Ccs)2Cl2. Tetrahedral monomeric and dimeric structures with bridging halide atoms, and pentacoordinate geometries are present in the zinc(II), cadmium(II), and mercury(II) complexes. The water resulted always uncoordinated lattice water. Assignments for the electronic spectra are proposed for all the above reported symmetries; the assignments for the metalligand and metal‐halides stretching modes have also been made. We have never observed a metalinduced ring opening under the present experimental conditions.

Quinoxaline 1,4-dioxide complexes with 3 d metal perchlorates[1

A series of 3 d metal perchlorate complexes with quinoxaline 1,4-dioxide(L) were synthesized and characterized by means of IR and electronic spectral and magnetic susceptibility (at 297-143 or 80°K) studies. With the exception of a 4:1 LCu(ClO 4) 2 complex, which is apparently monomeric, pentacoordinated of the type [CuL 4(OClO 3)](ClO 4), the spectral and magnetic evidence is in favor of bi- or polynuclear structures, involving terminal (L t ) and bridging quinoxaline 1,4-dioxide, aqua and unidentate perchlorato ligands, as well as ionic ClO 4 − and lattice water. The magnetic data point to significant spin-spin interactions in these bi- or polynuclear complexes; this is suggestive of coordination of the bridging L groups through only one of their NO oxygens, which acts as a bridge between neighboring metal ions (M ▪M or M(L b ) 2M bridging) rather than functioning as bidentate, with each of the NO oxygens coordinating to a different metal ion (M( b L b )M bridges). Proposed structural types are as follows for the binuclear, hexacoordinated new complexes: [(H 2O)(O 3ClO) 2(L t )Cr(L b ) 2Cr(L t )(OClO 3) 2(OH 2)](ClO 4) 2·6H 2O; (H 2O)(O 3ClO)(L t ) 2Fe(L b ) 2Fe(L t ) 2(OClO 3)(OH 2)](ClO 4) 4·8H 2O; and [(H 2O)(O 3ClO)(L t ) 2M(L b ) 2M(L t ) 2(OClO 3)(OH 2)](ClO 4) 2· 10H 2O (M = Mn, Fe, Co, Ni, Zn). For a second Cu(II) complex, involving a 3:2 L to Cu ratio, the relatively small μ eff decrease (0.29 μB) in the 295-82°K range, favors an oligomeric pentacoordinated structure, comprising both possible kinds of bridging L (i.e. characterized by −Cu(L b ) 2Cu( b L b )- sequences).

SPIROPHOSPHORANES – STRUCTURE REACTIVITY

Abstract The first part of this article will deal with the reactions of spirophosphoranes with a P[sbnd]H bond. These compounds contain two five-membered rings and have four oxygen atoms, or three oxygen atoms and one nitrogen atom, or two oxygen and two nitrogen atoms directly bonded to the phosphorus atom, which in all cases bears an hydrogen atom (Scheme 1). The most remarkable property of these compounds is undoubtedly their ability to give rise to a tautomeric equilibrium between the tri- and penta-coordinated structures PIII→PV.

Coordination compounds of hydrazine derivatives with transition metals. X. Cobalt(II) aroylhydrazone complexes

Abstract The reactions of some aroylhydrazones (HL) with cobalt(II) salts were investigated and chelates of the types [Co(HL) 2 X 2 ] and [Co(L) 2 ] were isolated. Analytical data, infrared studies, magnetic moments and solution spectra as well as some conductivity measurements were used to characterise these chelates. The [Co(HL) 2 X 2 ] chelates were found to possess octahedral configuration in solid state but dissociate in DMF solutions. Attempts were made to identify the dissociation products. A dimeric pentacoordinate structure was tentatively assigned for the neutral [Co ( L ) 2 ] chelates.

Penta- and hexa-coordinate adducts of bis(diaryldithiophosphinato) cobalt(II)

Abstract Pentacoordinate adducts of composition Co(X)2(L) where X = diphenyldithiophosphinato or di(p-tolyl)dithiophosphinato and L = α-picoline, β-picoline, λ-picoline, 2-aminopyridine, quinoline and isoquinoline and the hexacoordinate adducts Co(X)2(L)2 where L = pyridine, λ-picoline and isoquinoline are reported. The spectral studies and magnetic measurements over a temperature range 79−350°K are consistent with the proposed pentacoordinate structure for 1:1 adducts and hexacoordinate structure for 1:2 adducts. Thermal decomposition of the adducts leads to the conclusion that the steric effects are likely to be responsible for the formation of 1:1 adducts.

Mössbauer and infrared spectroscopic studies of some organotin(IV) schiff base complexes

Several organotin(IV) complexes with quadri- and terdentate anionic Schiff base ligands have been investigated in the solid state using 119Sn Mössbauer and IR spectroscopies, Mössbauer parameters derived from both zero-field and magnetically perturbed spectra suggest that the R2Sn(Salen)(R = Me, Et, Ph) and Me2Sn(Saldap-2OH) complexes have similarly distorted trans-octahedral structures. However, in Ph2Sn(HSaldap-2-O) the ligand appears to be only terdentate, leading to a penta-coordinate structure similar to those of the R2Sn(Sal-N-2-OC6H4) derivatives (R = Me, Ph). For Ph3Sn(Sal-N-2-OC6H4) the asymmetry parameter of the electric field gradient is close to unity, confirming a mer-octahedral configuration for this complex.

THE CO-ORDINATION CHEMISTRY OF DIVALENT COBALT, NICKEL AND COPPER Part III. Five-coordinate Cobalt(II) Complexes with Bis(Acetamido)thioether derivatives

Abstract Preparation and properties of new cobalt(II) complexes using ligands with OSO sets of donor atoms, viz. bis(N,N-dimethylacetamido)-thioether (TTDA) and bis(N-methyl-N-phenylacetamido)thioether (DTDA), are reported. Magnetic, spectral and non-aqueous conductivity data were obtained. Penta-coordinate structures are proposed for solid CoX2. TTDA (X = Cl−, Br−, I−, NO3 − and NCS-) and CoX2. DTDA (X = Cl−, Br− and NCS-). Similar data for Co(NO3)2. DTDA and Co(ClO4)2. 2TTDA strongly suggest distorted octahedral structures for these. Gaussian analysis on the solid reflectance spectra were done.

Reactivity of metalmetal bonds VI. Cleavage reactions of (trimethyltin) pentacarbonyl manganese

The cleavage reactions of (CH 3) 3SnMn(CO) 5 with chlorine, iodine, hydrogen chloride, hydrogen bromide, hydrogen iodide, iodine menochloride, and trifluoroiodomethane are described, as well as some similar reactions of (C 5H 5) 3PbMn(CO) 5. The results are compared with analogous reactions of other metal−metal bonded organometallic compounds. Boron trifluoride with (CH 3) 3SnMn(CO) 5 gave [(CH 3) 2- SnMn(CO) 5]BF 4, the same compound also being formed from silver tetrafluoroborate and Cl(CH 3) 2SnMn(CO) 5. the analogous hexafluorophosphate and hexafluoroarsenate salts containing the [(CH 3) 2SnMn(CO) 5] + ion could not be obtained from similar reactions. The preparation of CF 3(CH) 2SnMn(CO) 5 and [CH 3) 2- SnMn(CO) 5]BF 3CF 3 are described, but the reaction of sodium tetraphenylborate with Cl(CH 3) 2SnMn(CO) 5 gave C 6H 5(CH 3) 2SnMn(CO) 5 and no the expected tetraphenylborate salt. The infrared spectra of [(CH 3) 2SnMn(CO) 5]BF 4 and the related BF 3CF 3- salt are very similar to those of their trimethyltin analogues, and their probable pentacoordinate structures are discussed.

Co-ordination chemistry of indium. Part VI. Far-infrared spectra of indium trihalide adducts with neutral donors

Infrared spectra have been obtained over the range 70–4000 cm.–1 for complexes of the types InX3L3 and InX3L2, where X = Cl, Br, and I and L = donor ligand. The evidence indicates a pentaco-ordinate monomeric structure for the InX3L2 series [L = Ph3PO, Ph3P, or ½(Ph2P·C2H4·PPh2)] in the solid state, the trans-octahedral form for InX3(dimethyl sulphoxide)3, and the cis-octahedral structure for InX3py3.

Intramolecular racemization processes in pentacoordinate structures

ADVERTISEMENT RETURN TO ISSUEPREVArticleIntramolecular racemization processes in pentacoordinate structuresEarl L. MuettertiesCite this: Inorg. Chem. 1967, 6, 3, 635–638Publication Date (Print):March 1, 1967Publication History Published online1 May 2002Published inissue 1 March 1967https://doi.org/10.1021/ic50049a049RIGHTS & PERMISSIONSArticle Views65Altmetric-Citations22LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (503 KB) Get e-Alerts Get e-Alerts