Helices of ruthenium complexes involving pyridyl–azine ligands: synthesis, spectral and structural aspects

New cationic complexes [Ru(η5-C5H5)(EPh3)(L)]BF4 [L = pyridine-2-carbaldehyde azine (paa); E = P, 1; E = As, 2; E = Sb, 3] and κ1 bonded dppm complexes [Ru(η5-C5H5)(κ1-dppm)(L)]BF4 [L = paa 4; L = p-phenylene-bis(picoline)aldimine (pbp) 5] containing both group V donor and pyridyl–azine ligand are reported. The complexes were fully characterized by analytical and spectral studies. 31P NMR spectral studies suggested coordination of dppm in the complexes 4 and 5 in κ1-manner, which was further, confirmed by structural studies on the representative complex 4. Weak interaction studies revealed that inter- and intramolecular C–H⋯X (X = O, F, Cl, π) and π–π interactions in the complexes 1 and 4 lead to helical structures.