Structural and spectroscopic studies of transition metal nitrite complexes. II. Crystal structures of cis-Bis(ethane-1,2-diamine)(nitrito-O,O')zinc(II) nitrite and trans-Bis[N,N-dimethyl(ethane-1,2-diamine)]dinitritozinc(II)

1981 ◽  
Vol 34 (10) ◽  
pp. 2061 ◽  
Author(s):  
AJ Finney ◽  
MA Hitchman ◽  
CL Raston ◽  
GL Rowbottom ◽  
AH White
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Crystal Structures ◽  
Coordination Polyhedron ◽  
Metal Ion ◽  
Spectroscopic Studies ◽  
Bond Lengths ◽  
Coordination Sites ◽  
Metal Ligand ◽  
Ligand Bond

The crystal structures of the complexes cis-bis(ethane-1,2-diamine)(nitrito-O,O')zinc(II) nitrite and trans-bis[N,N-dimethyl(ethane-l,2-diamine)]dinitritozinc(II) are described. The former compound contains one chelating nitrite, the second group being present as a counter ion. In this complex the coordination polyhedron about the metal ion may be described either as a distorted trigonal bi-pyramid or an octahedron, depending upon whether the chelated nitrite is considered to occupy one or two coordination sites. The second compound is a trans nitrito complex, having an octahedral ligand geometry, though with three markedly different metal-ligand bond lengths. The structures of the complexes are compared with those of analogous nickel(II) nitrite complexes, and the differences are discussed in terms of the electron configurations of the two metal ions.

Metal ion – biomolecule interactions. Part 16. C(2)-H isotopic exchange in Co(III)-coordinated imidazoles

1995 ◽  
Vol 73 (6) ◽  
pp. 772-780 ◽  
Author(s):  
Erwin Buncel ◽  
Fan Yang ◽  
Robert Y. Moir ◽  
Ikenna Onyido
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Hydrogen Exchange ◽  
Isotopic Exchange ◽  
Negative Charge ◽  
Ligand Complex ◽  
Transition State Stabilization ◽  
Anionic Species ◽  
Metal Ligand ◽  
Ligand Bond

Transition-metal-bound imidazoles are suitable models for evaluating the roles of metal ions in biomolecules having the imidazole moiety and similar heterocyclic residues as part of their structure. Such studies provide useful insights into metal–biomolecule interactions in biological systems, especially when the lability of the metal–ligand bond is substantially reduced, such that the identity of the metal–ligand complex is preserved during the course of the reaction under investigation. The present paper reports on a kinetic study of tritium exchange from the C(2) position of the imidazole moiety in the substitution-inert complex cations [Co(NH3)5[2-3H]-imidazole]3+ (1) and [Co(NH3)5-1-methyl-[2-3H]-imidazole]3+ (2). Rate–pH profiles have been determined in aqueous solution at 60 °C. Both substrates are believed to react through rate-determining attack of hydroxide ion (kM+ pathway) at C(2)-T. Dissection of the kinetic data reveals an additional pathway for 1 consequent upon deprotonation of its pyrrole-like N-H(T) to yield 3, which is then attacked by hydroxide at C(2) (kM pathway). The ratio kM+/kM = 103 that is obtained is in accord with the expected reduced reactivity of 3. Comparison of the present data with those reported for a variety of heterocyclic substrates shows that the order of reactivity, protonated [Formula: see text] metal ion coordinated [Formula: see text] neutral form of substrates, prevails. The superiority of the proton over metal ions in catalyzing isotopic hydrogen exchange is attributed to its larger ground state acidifying effect coupled with the greater transition state stabilization it affords, relative to metal ions. The exchange reaction of 3 via the kM pathway is the first example of a reactive anionic species in which the negative charge is located α to the exchanging C-H. Keywords: tritium exchange, cobalt (III)-coordinated imidazoles.

155Gd Mössbauer Spectroscopic Study of GdM(CN)6 · 4H2O (M = CrIII, FeIII and CoIII) and KGdM(CN)6 · 3H2O (M = FeII and RuII)

2002 ◽  
Vol 57 (6-7) ◽  
pp. 581-585 ◽  
Author(s):  
Junhu Wang ◽  
Junko Abe ◽  
Takafumi Kitazawa ◽  
Masashi Takahashi ◽  
Masuo Takeda
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Spectroscopic Study ◽  
Crystal Structures ◽  
Transition Metal Ions ◽  
Spectroscopic Studies ◽  
Coupling Constants ◽  
Orthorhombic Distortion ◽  
Ionic Radii ◽  
Quadrupole Coupling

155Gd Mössbauer spectroscopic studies of the title complexes have been performed. Although the 155Gd isomer shifts (d) varied scarcely, the quadrupole coupling constants (e2qQ) changed in the range 4.07-4.81 mm s-1. The e2qQ values of KGdM(CN)6 · 3H2O (M = FeII and RuII) are larger than those of GdM(CN)6 · 4H2O (M = CrIII, FeIII, and CoIII), these values increasing with increasing orthorhombic distortion of the crystal structures. A relationship between the e2qQ values and the ionic radii of the transition metal ions has also been recognized

scholarly journals Kristallstrukturen der [2.2.2]Cryptate [Cd(cryptand 222)][CdCl4] und [Hg(cryptand 222)][Hg2Cl6] mit achtfach koordinierten Metallionen / Crystal Structures of the [2.2.2]Cryptates [Cd(cryptand 222)][CdCl4] and [Hg(cryptand 222)][Hg2Cl6] with 8-Coordinated Metal Ions

1994 ◽  
Vol 49 (8) ◽  
pp. 1031-1035 ◽  
Author(s):  
Joachim Pickardt ◽  
Britta Kühn
Keyword(s):  
Metal Ions ◽  
Crystal Structures ◽  
Coordination Polyhedron ◽  
Mercuric Chloride ◽  
Cadmium Chloride ◽  
Monoclinic Space Group ◽  
Space Group ◽  
Bond Lengths ◽  
Cryptand 222

Reactions of [2.2.2]cryptand, 4,7,13,16,21,24-Hexaoxa-1,10-diazabicyclo-[8.8.8]hexacosane, (“cryptand 222”) with cadmium chloride and mercuric chloride yielded crystals of [Cd(cryptand 222)][CdCl4] (1) and [Hg(cryptand 222)][Hg2Cl6] (2). 1 crystallizes tetragonally, space group P42/n, Z = 4, a = 1239.8(2), c = 1801.2(8) pm; 2 is monoclinic, space group P2/n, Z = 2, a = 1060.3(3), b = 955.2(2), c = 1607.0(3) pm. and β = 108.85(2)°. In the cations of both complexes the metal ions are enclosed in the bicyclic ligand and show 8-coordination to its six oxygen and two nitrogen atoms, the coordination polyhedron is a distorted cube for 1 and a bicapped trigonal antiprism for 2. The anion of 2 is dimeric, the two mercury atoms are connected via chlorine bridges with Hg-Cl distances of 258 and 278 pm, the Hg-Cl bond lengths to the two terminal chloro ligands being shorter at 236 and 238 pm.

Structural and spectroscopic studies of transition metal nitrite complexes. VIII. Crystal structures and spectra of three pentanuclear species with stoichiometry [Ni5(N-substituted ethane-1,2-diamine)4(OH)2(NO2)8]

1981 ◽  
Vol 34 (10) ◽  
pp. 2139 ◽  
Author(s):  
AJ Finney ◽  
MA Hitchman ◽  
CL Raston ◽  
GL Rowbottom ◽  
AH White
Keyword(s):  
Transition Metal ◽  
Crystal Structures ◽  
General Formula ◽  
Infrared Spectra ◽  
Spectroscopic Studies ◽  
Molecular Structures ◽  
Structural Variations ◽  
Crystal And Molecular Structures

The preparation of a series of novel compounds of general formula [Ni5L4(NO2)8(OH)2] formed by ethane-1,2-diamine or one of five N-substituted ethane-1,2-diamines (L) is described. The crystal and molecular structures of the ethane-1,2-diamine, N,N'-diethylethane-1,2-diamine and N,N-dimethylethane-1,2-diamine complexes are reported. Each compound contains a planar, pentameric arrangement of nickel(II) ions, linked by bridging hydroxide and nitrite ligands. The details of the nitrite bridges differ among the complexes, causing differences in their electronic and infrared spectra. The structural variations are probably caused by the differing steric requirements of the amine substituents.

The Crystal and Molecular Structures of Two Modifications of cis-Dichloro-mer-tris-(dimethylphenylphosphine)hydridoiridium(III)

1988 ◽  
Vol 41 (3) ◽  
pp. 283 ◽  
Author(s):  
GB Robertson ◽  
PA Tucker
Keyword(s):  
Heavy Atom ◽  
Molecular Structures ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray ◽  
Bond Lengths ◽  
Metal Ligand ◽  
Ligand Bond

The structures of two crystalline modifications of mer -(Pme2Ph)3H-cis-Cl2IrIII, (1), have been determined from single-crystal X-ray diffraction data. Modification (A) is monoclinic, space group P21/c with a 12.635(1), b 30.605(3), c 14.992(2)Ǻ, β 110.01(2)° and Z = 8. Modification (B) is orthorhombic, space group Pbca with a 27.646(3), b 11.366(1), c 17.252(2)Ǻ and Z = 8. The structures were solved by conventional heavy atom techniques and refined by full-matrix least- squares analyses to conventional R values of 0.037 [(A), 8845 independent reflections] and 0.028 [(B), 5291 independent reflections]. Important bond lengths [Ǻ] are Ir -P(trans to Cl ) 2.249(1) av. (A) and 2.234(1) (B), Ir -P(trans to PMe2Ph) 2.339(2) av. (A) and 2.344(1), 2.352(1) (B), Ir-Cl (trans to H) 2.492(2), 2.518(2) (A) and 2.503(1) (B) and Ir-Cl (trans to PMe2Ph)2.452(2) av. (A) and 2.449(1)(B). Differences in chemically equivalent metal- ligand bond lengths emphasize the importance of non-bonded contacts in determining those lengths.

Self assembly of a tren-derivative hydrogenated Schiff base with transition metal ions: syntheses, crystal structures and photoluminescent properties

CrystEngComm ◽  
2012 ◽  
Vol 14 (8) ◽  
pp. 2879 ◽  
Author(s):  
Yuehong Wen ◽  
Tianlu Sheng ◽  
Qilong Zhu ◽  
Shengmin Hu ◽  
Chunhong Tan ◽  
...  
Keyword(s):  
Schiff Base ◽  
Transition Metal ◽  
Metal Ions ◽  
Crystal Structures ◽  
Self Assembly ◽  
Transition Metal Ions
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