Table 2.

Significant vibration bands of the [Ru₂(p-cymene)₂(L1)₂]X₂ complexes, useful for determining the mode of coordination of the ligands

Compound	ν(C=N)	νs(NO2)	ν(N–N)	δ(NO2) + furana	Other bands
HL1b	1602	1356	1108	811
[Ru2(p-cymene)2(L1)2]Cl2	1605	1349	1160	809
HL2b	1599	1354	1114	808
[Ru2(p-cymene)2(L2)2](PF6)2	1588	1351	1168	813	νa(PF) 847; δa(FPF) 558
HL3b	1602	1352	1104	805
[Ru2(p-cymene)2(L3)2](PF6)2	1586	1351	1172	813	νa(PF) 846; δa(FPF) 558
HL4b	1595	1344	1104	811
[Ru2(p-cymene)2(L4)2]Cl2	1602	1338	1166	809

ν: stretching; δ: bending; a: asymmetric;

^aδ(NO₂) + furan modes or furan hydrogen wagging symmetric modes;

^bFrom reference 38.