Template-controlled assembly of ditopic catechol phosphines: a strategy for the generation of complexes of bidentate phosphines with different bite a…

2008

A rational approach to the synthesis of heterobi- or -trimetallic complexes based upon self-assembly of a flexible ditopic catechol-phosphine ligand with [(cod)PdCl(2)] and simple metal halides such as GaCl(3), BiCl(3), SnCl(4), or ZrCl(4) is described. All products were characterized by spectroscopic and analytical data and single-crystal X-ray diffraction studies. The molecular structures can be described in terms of cis-configured palladium complexes with supramolecular bisphosphine ligands that are formed by the assembly of two phosphine catecholate fragments on a main group/transition metal template. Of particular interest are the distinct decreases in P-Pd-P bite angles and P...P dist…

Corrosion of Heritage Objects: Collagen‐Like Triple Helix Found in the Calcium Acetate Hemihydrate Crystal Structure

2020

Abstract Helical motifs are common in nature, for example, the DNA double or the collagen triple helix. In the latter proteins, the helical motif originates from glycine, the smallest amino acid, whose molecular confirmation is closely related to acetic acid. The combination of acetic acid with calcium and water, which are also omnipresent in nature, materializing as calcium acetate hemihydrate, was now revealed to exhibit a collagen‐like triple helix structure. This calcium salt is observed as efflorescence phase on calcareous heritage objects, like historic Mollusca shells, pottery or marble reliefs. In a model experiment pure calcium acetate hemihydrate was crystallized on the surface of…

2-Organoselenomethyl-1H-benzimidazole Complexes of Copper(II) and Copper(I)

2009

Structurally characterized 2-methylselenomethyl-1H-benzimidazole (msbi) is shown to form complexes in 2:1 ratio with copper(II). Whereas the central cation [Cu(msbi)2Cl]+ = 1+ in [Cu(msbi)2Cl]Cl·2MeOH crystallizes in an approximately mixed square-pyramidal/trigonal-bipyramidal structure (τ = 0.52) with the second and third row atoms chlorine and selenium in the equatorial plane, the related [Cu(msbi)2(MeOH)](BF4)2 = [2](BF4)2 exhibits a closer to square-pyramidal arrangement with τ = 0.36 for that complex dication 22+. In both cases, the Cu–N bonds are short at about 1.94 A, whereas the Cu–Se distances vary between 2.62 A for 1+ and ca. 2.54 A for 22+. Slight differences between the Jahn–Te…

Korrosion von Kulturgut: Entdeckung einer kollagenartigen Tripelhelix in der Kristallstruktur von Calciumacetat‐Hemihydrat

2020

CCDC 1958904: Experimental Crystal Structure Determination

2020

Related Article: Sebastian Bette, Jörg Stelzner, Gerhard Eggert, Thomas Schleid, Galina Matveeva, Ute Kolb, Robert E. Dinnebier|2020|Angew.Chem.,Int.Ed.|59|9438|doi:10.1002/anie.202001609