Synthesis of a series of ruthenium and rhodium complexes with tridentate pyridine-based ligands containing hydrogen bonding groups

A series of ruthenium and rhodium complexes with a urea–disubstituted pyridine ligand are reported. The X-ray crystal structures of three of these species, RuCl2(L1)(PPh3) (1), [Ru(MeCN)2(L1)(PPh3)][BF4]2 (3) and Rh(CH2Cl)Cl2(L1) (9) (where L1 = N,N′-(2,2′-(1E,1′E)-(1,1′-(pyridine-2,6-diyl)bis(ethan-1-yl-1-ylidene))bis(azan-1-yl-1-ylidene)bis(ethane-2,1-diyl))diacetamide) have shown that the disubstituted pyridine acts as a tridentate ligand and its urea substituents engage in hydrogen bonding interactions with species coordinated to the metal centres. The reactivity of the ruthenium complexes towards coordination of other anions such as NCS− has been investigated, as well as the oxidative-addition of alkyl chlorides to rhodium(I) centres (to yield species such as 9).

Graphical abstractA series of ruthenium and rhodium complexes with urea- and amide-disubstituted pyridine ligands have been prepared. X-ray crystal structure of some of these complexes have demonstrated that in the solid state the amide substituents of the ligands are engaged in hydrogen-bonding with species coordinated to the metal centre. This could provide interesting possibilities for the activation of small molecules in the coordination sphere of metal complexes.Figure optionsDownload full-size imageDownload as PowerPoint slide