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Synthesis and Crystal Structures of Palladium(II) Complexes of Macrobicyclic Azathiaether Ligands
Author(s) -
Siedle Gabriel,
Kersting Berthold
Publication year - 2003
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200300165
Subject(s) - chemistry , thioether , palladium , ligand (biochemistry) , crystal structure , hexacoordinate , stereochemistry , medicinal chemistry , nuclear magnetic resonance spectroscopy , crystallography , octahedron , ethylene , catalysis , organic chemistry , biochemistry , receptor , silicon
The macrobicyclic azathioether ligands L 1 and L 2 were investigated regarding their capability to form complexes with divalent palladium. L 1 represents a cyclophane‐like ligand system comprising two 4‐ tert ‐butyl‐2, 6‐bis(aminomethyl)thiophenolate units, which are linked by an ethylene and two 3‐ aza ‐1, 5‐pentylene units to give two seventeen‐membered di thia ‐tri aza crowns fused at the common ArSCH 2 CH 2 SAr fragment. L 2 is the hexa‐ N ‐methylated derivative of L 1 . Treatment of L 1 and L 2 with two equivalents of [PdCl 2 (CH 3 CN) 2 ] gave the new complexes [(L 1 )Pd 2 Cl] + ( 1 ) and [(L 2 )Pd 2 Cl 2 ] 2+ ( 2 ), respectively, which were isolated as perchlorate salts and characterized by elemental analysis, IR and NMR spectroscopy and by X‐ray crystallography. In 1 , L 1 acts as a septadentate ligand to give two distorted square‐planar PdN 3 S and PdN 3 Cl units, respectively. The structure of 2 shows L 2 to be hexacoordinate, yielding two distorted square‐planar PdN 2 SCl units leaving two NMe groups dangling. NMR spectroscopic studies reveal that both complexes retain their solid‐state structures in solution. The reaction of L 2 with one equivalent of [PdCl 2 (CH 3 CN) 2 ] is accompanied by a bond cleavage reaction of one of the two aliphatic thioether bonds to afford the dinuclear complex [(L 3 )Pd 2 Cl 2 ]Cl ( 3 ·Cl) of the ring‐opened 24‐membered hexaaza‐vinylthioether/thiophenolate derivative (L 3 ) ‐ . The crystal structure determination of 3 ·Cl reveals two distorted‐square planar PdN 2 ClS units which are bridged by the thiophenolate sulfur atom of (L 3 ) ‐ . The vinyl‐thioether moiety and the two remaining amine donors of (L 3 ) ‐ do not interact with the two palladium ions. The X‐ray structure analysis of the free macrocycle L 2 demonstrates that the C‐S bond lengths become elongated upon coordination to the palladium(II) ions.