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Solvent Effects on Coordination Chemistry – Stepwise Synthesis and Structural Properties of Monometallic Palladium(II) Complexes and Bimetallic Palladium(II)/Platinum(II) Complexes
Author(s) -
Noh Tae Hwan,
Lee YoungA,
Jung OkSang
Publication year - 2010
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200900804
Subject(s) - palladium , chemistry , bimetallic strip , platinum , medicinal chemistry , ethylenediamine , ligand (biochemistry) , tetramethylethylenediamine , stereochemistry , inorganic chemistry , metal , catalysis , organic chemistry , biochemistry , receptor
Stepwise syntheses of monometallic palladium(II) and bimetallic palladium(II)/platinum(II) complexes were carried out in order to measure the metallophilicity of potential tetradentate bis(alkylthio)ylidenemalonato ligands. The reaction of [Pd](SO 4 ) ([Pd] = (Me 4 en)Pd; Me 4 en = N , N , N′ , N′ ‐tetramethylethylenediamine) with Ba[L] {L: bis(methylthio)methylenepropanedioato ( 1 ); bis(ethylthio)methylenepropanedioato ( 2 ); 1,3‐dithiapan‐2‐ylidene‐malonato ( 3 )} produced [[Pd]‐ O , O′ ‐L]. Successive reactions of [[Pd]‐ O , O′ ‐L] with {M}(NO 3 ) 2 ({M} = (en)M; en = ethylenediamine; M = Pd II , Pt II ), followed by anion exchange with PF 6 – , yielded banana‐shaped bimetallic complexes [[Pd]‐ O , O′ ‐L‐ S , S′ ‐{M}](PF 6 ) 2 . In case of [[Pd]‐ O , O′ ‐ 1 ], the bis(alkylthio)methylene group of 1 was bent strikingly from the palladium square plane (dihedral angle = 78.26°), in contrast to the cases of [[Pd]‐ O , O′ ‐ 3 ] (120.84°) and [[Pd]‐ O , O′ ‐L‐ S , S′ ‐{M}](PF 6 ) 2 (101.75–103.54°). [[Pd]‐ O , O′ ‐L] (L = 1 , 2 ) in Me 2 SO existed as a mixture of [[Pd]‐ O , O′ ‐L] and [(Me 4 en‐ N )(Me 2 SO‐ S )‐Pd‐ O , O′ ‐L] in a mol ratio of 1:1. For the labile species, a linkage isomeric equilibrium between [[Pd]‐ O , O′ ‐L] and [[Pd]‐ O , S ‐L] in D 2 O was observed. [[Pd]‐ O , O′ ‐ 3 ] and [[Pd]‐ O , O′ ‐L‐ S , S′ ‐{M}](PF 6 ) 2 , however, were found to be inert in Me 2 SO or D 2 O. Such notably different solution behavior possibly can be explained by the steric hindrance occurring via the dihedral angles between the palladium square plane and the ylidene moiety. Variable‐temperature 1 H NMR spectra of the banana‐shaped bimetallic complexes [[Pd]‐ O , O′ ‐L‐ S , S′ ‐{M}](PF 6 ) 2 in CD 3 CN solution revealed that the amine proton resonances are sensitive to the fluxional motion of the remote bis(alkylthio)ylidene groups, suggesting the occurrence of interconversion between the two “bent‐up” and “bent‐down” forms.