Eight-Coordinate Complexes of Cobalt(II). A Principle Influencing the Occurrence of High Coordination Numbers

1964 ◽  
Vol 86 (14) ◽  
pp. 2941-2942 ◽  
Author(s):  
F. A. Cotton ◽  
J. G. Bergman
Keyword(s):  
Coordination Numbers ◽  
High Coordination

Fluorescent phenoxy benzoxazole complexes of zirconium and hafnium: synthesis, structure and photo-physical behaviour

2018 ◽  
Vol 47 (32) ◽  
pp. 11245-11252 ◽  
Author(s):  
Lisa Kuhlmann ◽  
Rafael Methling ◽  
Jasmin Simon ◽  
Beate Neumann ◽  
Hans-Georg Stammler ◽  
...  
Keyword(s):  
Coordination Numbers ◽  
Physical Behaviour ◽  
Blue Region ◽  
High Coordination

Ten new Zr(iv) and Hf(iv) complexes with phenoxy-benzoxazole ligands with high coordination numbers up to eight show ligand-centered fluorescence with emission maxima in the blue region.

Wechselwirkungen in Molekülkristallen, 156 [1, 2]. Kristallzüchtung und Strukturbestimmung von (Imidodiphosphat)-Alkalisalzen mit Kationen niedriger und hoher Koordinationszahlen / Interaction in Molecular Crystals, 156 [1, 2]. Crystal Growth and Structure Determination of Alkali(imidodiphosphate) Salts with Cations of Low and High Coordination Numbers

2000 ◽  
Vol 55 (9) ◽  
pp. 773-784 ◽  
Author(s):  
Hans Bock ◽  
Erik Heigel ◽  
Norbert Nagel
Keyword(s):  
Crystal Growth ◽  
Coordination Number ◽  
Molecular Crystals ◽  
Chelating Ligands ◽  
Chain Polymer ◽  
Coordination Numbers ◽  
Structural Differences ◽  
A Chain ◽  
High Coordination

Imidodiphosphates ⊖N[PO(OR)2]2 and Imidodiphosphonates ⊖N[POR2]2 are effective chelating ligands for a variety of metal cations including even Na⊕, for which a lipophilically wrapped hexameric polyion cluster has been structurally characterized. The corresponding hexameric lithium and polyrubidium ion complexes reported here exhibit considerable structural differences: The rather small Li⊕ cations of coordination number five and tetraphenylimidodiphosphate form an isolated hexameric aggregate analogous to the Na⊕ one, whereas the larger Rb⊕ with coordination number seven and (3,4-dimethylphenyl)substituents crystallizes as a chain polymer. Based on the crystal structures, the dominant Coulomb attractions between cations and anions, the spatial requirement of the ligands and the essential phenyl/phenyl interactions in their lipophilic skin are discussed

Dimorphic EuCu5Cd

2012 ◽  
Vol 67 (10) ◽  
pp. 1107-1114 ◽  
Author(s):  
Frank Tappe ◽  
Christian Schwickert ◽  
Rainer Pöttgen
Keyword(s):  
Magnetic Susceptibility ◽  
Small Degree ◽  
Muffle Furnace ◽  
Temperature Dependent ◽  
X Ray ◽  
Coordination Numbers ◽  
Dsc Measurements ◽  
Divalent Europium ◽  
Experimental Magnetic Moment ◽  
High Coordination

Two modifications of EuCu5Cd were synthesized from the elements in sealed tantalum ampoules.The high-temperature (HT) modification was obtained from an induction-melted sample that was finally annealed at 873 K, while the low-temperature (LT) phase is formed in a muffle furnace by annealing a pre-melted sample at 673 K. DSC measurements gave a transition temperature of 823±2 K. Both structures were refined on the basis of single-crystal X-ray diffractometer data: R3̄m, a = 511:58(7), c = 3059:6(6) pm, wR2 = 0.0289, 316 F2 values, 22 variables for HTEuCu4 :85(1)Cd1:15(1) and Pnma, a = 2545:6(5), b = 511:60(1), c = 1060:3(2) pm, wR2 = 0.0386, 2044 F2 values, 121 variables for LT-EuCu4:92(1)Cd1:08(1). A small degree of Cu/Cd mixing was observed for three sites. Both structures adopt new types. The europium atoms have high coordination numbers of 18, 19 and 20 in LT- and 18 and 20 in HT- EuCu5Cd. These three types of polyhedra are the basic building units also in the closely related structures of CeCu6, CeCu5Au, CeCu4:38In1:62, and CeNi5Sn, a family of stacking variants. Temperature-dependent magnetic susceptibility measurements of a HT- EuCu5Cd sample showed an experimental magnetic moment of 7.56(1) μB per Eu atom in the paramagnetic regime, compatible with divalent europium. HT- EuCu5Cd orders antiferromagnetically at 17.7(5) K.

Stabilization of Metal Alkoxides (M = BA, CU) by Alkamolamines

1992 ◽  
Vol 271 ◽  
Author(s):  
L. G. Hubert-Pfalzgraf ◽  
M. C. Massiani ◽  
J. C. Daran ◽  
J. Vaissermann
Keyword(s):  
Metal Alkoxides ◽  
Tetradentate Ligand ◽  
Coordination Numbers ◽  
High Coordination ◽  
Interchange Reactions

ABSTRACTAlcohol interchange reactions between barium and copper(II) methoxides and triethanolamine give Ba(teaH-l)2,2EtOH and [Cu(teaH-2)]4,3tea, respectively. Triethanolamine appears as a tetradentate ligand -chelating in the case of barium, bridging-chelating for copper - and thus ensures high coordination numbers for the metals - eight for Ba and five for Cu - thus decreasing their susceptibility to hydrolysis. The remaining hydroxyl functionality on the coordinated triethanolamine moities favors the formation of solvates with alcohols via H-bonding.

scholarly journals Robin Jon Hawes Clark. 16 February 1935—6 December 2018

2020 ◽  
Vol 68 ◽  
pp. 103-129
Author(s):  
Alwyn G. Davies ◽  
Paul F. McMillan
Keyword(s):  
Raman Spectroscopy ◽  
Inorganic Compounds ◽  
Resonance Raman Spectroscopy ◽  
Linear Chain ◽  
Mixed Valence ◽  
Far Infrared ◽  
Vanadium Complexes ◽  
Coordination Numbers ◽  
Metal Metal ◽  
High Coordination

Robin Clark was a distinguished physical/inorganic chemist who made major discoveries in the coordination chemistry of the early transition metals, especially of titanium and vanadium complexes with high coordination numbers (notably seven and eight) and of the structures and physical properties of mixed valence, linear chain and metal–metal bonded compounds. He applied far-infrared spectroscopy to study metal–ligand vibrations systematically and established the technique for structure elucidation of transition metal and main group compounds. He also developed Raman and resonance Raman spectroscopy applied to inorganic compounds and highly coloured solids including mineral samples. That work led to his seminal applications of microbeam Raman spectroscopy for the identification of pigments and other constituents of artworks and historical artefacts, thereby developing a basis for testing their provenance and the identification of forgeries.

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