Search results for "Central unit"
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Experimental and Computational Study of Unique Tetranuclear µ 3 ‐Chloride and µ‐Phenoxo/Chloro‐Bridged Defective Dicubane Cobalt(II) Clusters
2016
Two tetranuclear CoII clusters [Co4(L)2(µ3-Cl)2Cl2] have been prepared by using multidentate diaminobisphenolate ligands. The solid-state structures of the complexes were determined by single-crystal X-ray diffraction. The cores of the cluster compounds can be defined as a two-vertex-deficient dicubane geometry (pseudo-dicubane). In the central unit, the cobalt(II) cations are linked through phenoxide oxygen (outer bridges) and chloride anions (inner bridges), previously unprecedented in this type of cobalt cluster. The magnetic properties were studied by both experimental and computational methods. By using a combination of techniques, we were able to determine the nature and strength of t…
Formation of Triple‐Stranded Dinuclear Helicates with Dicatecholimine Ligands: The Influence of Steric Hindrance at the Spacer
2005
A series of new imine-bridged dicatechol ligands 3a–f-H4 with sterically demanding groups at the spacers are used for the formation of titanium(IV) complexes M4[(3)3Ti2]. All three ligands 3a–c-H4 form triple-stranded dinuclear helicates. When the bulky ligands 3a-H4 or 3c-H4 are used with potassium as the countercation, oligomeric or polymeric side products are also observed. The imine-bridged ligand 3e-H4 quantitatively forms helicates M4[(3e)3Ti2] and not a M4L6 tetrahedron as observed with Raymond’s analogous amide-bridged dicatechol ligand 3i-H4. NMR spectroscopic investigations at variable temperature show that ligand 3f-H4, which possesses a spiro fluorenyl group at the central unit …