16- 18-electron ruthenium(II) complexes of the neutral, potentially tridentate triamine logand 2,6-[bis(dimethylamino)methyl]pyridine (NN'N)

The potentially tridentate coordinating ligands NN‘N (2,6-bis[(dimethylamino)methyl]pyridine) and PNP (2,6-bis[(diphenylphosphino)methyl]pyridine) react with [RuCl2(PPh3)3] to give [mer,trans-RuCl2(NN‘N)(PPh3)] (1) and [mer,trans-RuCl2(PNP)(PPh3)] (2), respectively. Complex 1 functions as a starting material for a variety of Ru[NN‘N] complexes. It reacts with either 1 or 2 equiv of AgOTf (OTf- = SO3CF3-) to yield monocationic [RuCl(NN‘N)(PPh3)]OTf (3) and [RuOTf(NN‘N)(PPh3)]OTf (4), respectively. The molecular structure of 4 shows a pentacoordinated ruthenium(II) center with a square-pyramidal environment. The reaction of 1 with either 1 or 2 equiv of AgOTf in the presence of MeCN results in the formation of the six-coordinate mono- or dicationic complexes [mer-RuCl(MeCN)(NN‘N)(PPh3)]X (6a) (X = OTf-) and [mer,trans-Ru(MeCN)2(NN‘N)(PPh3)](OTf)2 (7), respectively. At 55 °C in acetonitrile, 1 converts quantitatively into 6b (X = Cl-) which is isostructural with 6a. Reaction of polymeric [RuCl2(nbd)]n (nbd =...