Study of complexes of platinum group metals containing nitrogen bases derived from pyridine aldehydes: Interesting molecular structures with unpredicted bonding modes of the ligands

Abstract

Keywords Arene ligands Pyridine aldehydes Schiff bases Ruthenium Rhodium and iridium a b s t r a c tA series of mono-cationic dinuclear half sandwich ruthenium, rhodium and iridium metal complexes have been synthesized using ((pyridin-2-yl)methylimino)nicotinamide (L1) and ((picolinamido)phenyl) picolinamide (L2) ligands: , 9; Ir, 10). All the complexes have been isolated as their hexafluorophosphate salts and fully characterized by use of a combination of NMR and IR spectroscopy. The solid state structure of three representatives 4, 6 and 9 has been determined by Xray crystallographic studies. Interestingly, in the molecular structure of 4, the first metal is bonded to two nitrogen atoms whereas the second metal center is coordinated to only one nitrogen atom with two terminal chloride ligands. Fascinatingly in the case of the complexes with the symmetrical ligand L2, both ruthenium centers having h 6 -arene groups are bonded to nitrogen atoms with a bridging chloride atom between the two metal centers, whereas the metals with h 5 -Cp* groups are bonded to the ligand N,O and N,N fashion.

Trinuclear Half‐Sandwich RuII, RhIII and IrIII Polyester Organometallic Complexes: Synthesis and in vitro Evaluation as Antitumor Agents

“…All complexes show that the metal centre adopts the so‐called “piano‐stool” geometry, with the metal coordinated to the pentamethylcyclopentadienyl or p ‐cymene ligand, one chloride ligand and N , N ‐ligand ( 5 and 6 ) or N , O ‐ligand ( 8 and 9 ). In 5 and 6 , the M–N distances follow the trends observed in other common N , N ‐coordinated metal complexes,28 while in 8 and 9 the M–N and N–O distances (Tables 1 and 2) are comparable to those observed in analogous rhodium and iridium (C 5 Me 5 ) complexes 29,30…”

Influence of Halogen Substitution in the Ligand Sphere on the Antitumor and Antibacterial Activity of Half-sandwich Ruthenium(II) Complexes [RuX(η6 -arene)(C5 H4 N-2-CH=N-Ar)]+

“…The Ru–Cl bond lengths are 2.4009(6) and 2.4047(4) Å whereas the Ru–N bonds distances lie between 2.071(2) and 2.085(6) Å (Table ) similar to those reported for related arene ruthenium complexes with N , N ' bidentate ligands ,. [15a], The N–Ru–N bond angles range between 76.75(8) and 76.84(5)°, whereas the N–Ru–Cl angles ranged from 83.74(4) to 85.45(4)° as observed in related complexes , …”

Synthesis, Spectroscopic and Molecular Studies of Half‐Sandwich η6‐Arene Ruthenium, Cp* Rhodium and Cp* Iridium Metal Complexes with Bidentate Ligands

“…Upon coordination with the metal atom, each metal complex has shown seven signals in the range around 9.00 to 7.30 ppm similar to free ligand, which is, indicated that formation of mononuclear complexes. For all these complexes, the signals of the coordinated dipyridyl and phenyl protons are shifted to considerable downfield as compared to free ligand due to consequence of their coordination to metal atoms 29. Besides these signals, complexes 1 and 5 exhibit a singlet signal at δ = 6.35 ppm for the protons of the benzene ligand.…”