Synthese und Charakterisierung von kronenetherstabilisierten Platin(IV)- Komplexen mit Aminosäureliganden / Synthesis and Characterization of Amino Acid Complexes of Platinum(IV) Stabilized by Crown Ethers
2014
Steinborn, Dirk | Gravenhorst, Olaf | Junicke, Henrik | Heinemann, Frank W.
Crown ether complexed pentachloro(aqua)platinic acid, (H₃O)[PtCl₅(H₂O)]·2(18-cr-6)·6H₂O (1) reacts with glycine, L-alanine, and DL-2-aminobutyric acid to give cis-[PtCl₄(O-glyH)(H₂O)]·(18-cr-6)·H₂O (4a)¹ and cis-[PtCl₄(O-amacH)(H₂O)]·(18-cr-6) (amacH = alaH 4b, abuH 4c), respectively, as well as (amacH₂)₂[PtCl₆]·2(18-cr-6) (amacH = glyH 5a, alaH 5b, abuH 5c). The crown ether complexed hexachloroplatinic acid, (H₃O) 2[PtCl₆]·2(18-cr-6) (2), reacts with glycine to afford (glyH₂)[PtCl₄(N,O-gly)]·2(18-cr-6)·1.25H₂O (6).The structures of 4b and 6 were determined by X-ray diffraction. The alanine ligand in 4b is a zwitterion that is coordinated to platinum by one oxygen atom of the carboxylate group only. The other oxygen atom is engaged in a strong hydrogen bond to the ds-coordinated aqua ligand. The glycinato ligand in 6 is N, O-coordinated at platinum forming an anion [PtCl₄(N,O-gly)]⁻ . The other oxygen atom of the carboxylate group is involved in a strong hydrogen bridge to the cation (glyH₂)⁺. In both complexes hydrogen bridges are formed between the -N⁺H₃ and -NH₂ groups of the amino acid ligands and the oxygen atoms of the crown ether molecules.
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