A comparative study of the coordination of saccharinate, thiosaccharinate and benzisothiozolinate ligands to cyclometalated [Pd(Me2NCH2C6H4-κN,C)(μ-Cl)]2: Molecular structures of [Pd(Me2NCH2C6H4-κN,C)(µ-X)]2 (X = sac, bit and tsac) and [Pd(Me2NCH2C6H4-κN,C)Cl(ampyH-κN)] (ampyH = 2-amino-3-methylpyridine)

Abstract

Abstract Reactions of [Pd(Me2NCH2C6H4-κ2N,C)(μ-Cl)]2 with two equivalents of sodium saccharinate (Nasac), thiosaccharin (Htsac) or sodium benzisothiozolinate (Nabit) results in the stepwise substitution of the bridging halides to form sequentially [Pd2(Me2NCH2C6H4-κ2N,C)2(μ-Cl)(μ-X)] (X = sac, tsac) and [Pd(Me2NCH2C6H4-κ2N,C)(μ-X)]2 (X = sac, tsac, bit). The molecular structures of all three disubstituted complexes are reported. In each the two metalated ligands bind in a chelate manner adopting a relative anti conformation, while the new ligands bridge the two palladium atoms adopting a relative cis conformation. The local conformation about each palladium differs with small ligand changes. Thus in the sac and bit complexes all nitrogens lie trans to one another, in the tsac complex they are cis. Conformational changes also lead to large differences in the non-bonded Pd…Pd distance which range over 0.5 A. Treatment of [Pd(Me2NCH2C6H4-κ2N,C)(μ-Cl)]2 with two equivalents of 2-amino-3-methylpyridine (ampyH) in the presence of NEt3 affords mononuclear [PdCl(Me2NCH2C6H4-κ2N,C)(ampyH-κ1N)] as a result of “bridge-splitting”, the ampyH ligand binding through the pyridyl-nitrogen and lying approximately perpendicular to the PdCClN2 plane as shown by a crystallographic study.