“…The distinction observed in solid state can be explained on the basis of a possible weak interaction between the noncoordinating nitrogen atom and the adjacent carbonyl carbon in [Ru(4)(CO) 2 Cl 2 ] rather than a different bulkiness between the CH in phenyl ring of 3 and the N in pyridyl ring of 4, because the interatomic distance between the N atom and the adjacent C atom in [Ru(4)(CO) 2 Cl 2 ] is fairly short (2.682(3) Å). This weak interaction has often been observed in ruthenium carbonyl complexes with noncoordinating pyridyl moieties (Mizukawa et al, 1999;, which contain both a pyridyl nitrogen (δ-) and a carbonyl carbon (δ+). The X-ray structures of terpyridyl complexes with the dimethoxyphenyl pendant have been determined.…”