Investigation of the coordination modes of tris(pyrazolylmethane)/1,4,7-trithiacyclononane ruthenium(II) complex ions by electrospray ionization mass spectrometry

authors	Izquierdo, RA; Madureira, J; Ramos, CIV; Santana-Marques, MGO; Santos, TM
nationality	International
journal	INTERNATIONAL JOURNAL OF MASS SPECTROMETRY
author keywords	Ruthenium complexes; Electrospray ionization mass spectrometry; 1,4,7-Trithiacyclononane; Tris(pyrazolyl)methane; Coordination modes; Ion pairs
keywords	COLLISIONALLY ACTIVATED DISSOCIATION; SOFT THIOETHER COORDINATION; TRANSITION-METAL COMPLEXES; NOESY NMR-SPECTROSCOPY; CHARGED ALKALINE-EARTH; GAS-PHASE COMPLEXES; STRUCTURAL-CHARACTERIZATION; AMINO-ACIDS; TRIS(PYRAZOLYL)METHANE LIGANDS; = 1,4,7-TRITHIACYCLONONANE
abstract	Electrospray ionization mass spectrometry (ESIMS) was used to investigate the coordination modes of the complexes [Ru-II([9]aneS(3))(HCpz(3))Cl]Cl, [Ru-II ([9]aneS(3))(HCpz(3))](Cl)PF6 and [Ru-II([9]aneS(3))(HCpz(3))](PF6)(2) ([9]aneS(3) = 1,4,7-trithiacyclononane; HCpz(3) = tris(1-pyrazolyl)methane) in methanol, acetonitrile and methanol/water solutions. The complex [Ru-II([9]aneS(3))(HCpz(3))Cl]Cl shows a rapidly exchangeable Cl ligand, with formation of a doubly charged ion [Ru-II([9]aneS(3))(HCpz(3))](2+), m/z 248, but the [Ru-II([9]aneS(3))(HCpz(3))Cl](+), m/z 531, is also observed and both species still coexist after 16 h. The formation of the [Ru-II([9]aneS(3))(HCpz(3))](2+) and [Ru-II([9]aneS(3))(HCpz(3))Cl](+) ions by electrospraying solutions of [Ru-II([9]aneS(3))(dmso)Cl-2] (dmso = dimethylsulfoxide) and HCpz(3) in water/methanol was also studied. Fragmentation of the [Ru-II([9]aneS(3))(HCpz(3))](2+) ions by losses from the[9]aneS(3) ligand seems to point to a k(3) strained coordination mode, whereas fragmentation of the [Ru-II([9]aneS(3))(HCpz(3))Cl](+) points to a less strained complex and to two isomers: the complex [Ru-II([9]aneS(3))(HCpz(3))Cl](+) and the ion pair [Ru-II([9]aneS(3))(HCpz(3))+Cl](+). Further support for the ion pair hypothesis is the strong increase of the relative abundance of the [Ru-II([9]aneS(3))(HCpz(3))+PF6](+) ion, m/z 641, formed from solutions of the [Ru-II(k(3)-[9]aneS(3))(k(3)-HCpz(3))](Cl)PF6 and [Ru-II(k(3)-[9]aneS(3))(k(3)-HCpz(3))](PF6)(2) complexes, after 16 h. The high stability of the ion pairs indicates that they may be inner sphere ion pairs and that either [9]aneS(3) or HCpz(3) changes from a k(3) to a k(2) coordination mode. The results support an equilibrium between a full k(3)-[9]aneS(3)/k(3)-HCpz(3) complex and a k(2) + k(3) + Cl/PF6 ion pair. (C) 2010 Elsevier B.V. All rights reserved.
publisher	ELSEVIER SCIENCE BV
issn	1387-3806
year published	2011
volume	301
issue	1-3
beginning page	143
ending page	150
digital object identifier (doi)	10.1016/j.ijms.2010.08.007
web of science category	Physics, Atomic, Molecular & Chemical; Spectroscopy
subject category	Physics; Spectroscopy
unique article identifier	WOS:000290190000017