N,N′-Diphenylamidines, PhNC(R)NHPh (R=H, Me, Et, Ph), and 1,3-diaryltriazenes, ArNNNHAr (Ar=p-C6H4X, X=H, Cl, Me, OMe) react with ruthenium(II) complexes, [RuCl2(C7H8)]n, [RuCl2(CO)2]n and [RuCl2(Me2SO)4] in the presence of a base (NEt3 or Na2CO3) to afford a selection of bis(chelate) products [Ru{PhNC(R)NPh}2L2] and [Ru(ArNNNAr)2L2] (L=CO, Me2SO; L2=C7H8). In contrast one particular combination — [RuCl2(Me2SO)4]/PhNC(H)NHPh/NEt3 — in refluxing dimethylformamide yields a novel amidine fragmentation product [RuCl(NH2Ph){PhNC(H)NPh}(Me2SO)2] which has been characterised by X-ray diffraction methods.