Kinetic studies of the interaction between organotin(IV)chlorides and tetraaza Schiff bases: Synthesis and characterization of some novel tin(IV) Schiff base complexes

Abstract

In this article the kinetics of the interaction between the teteraaza Schiff bases as donor with organotin(IV)chlorides as acceptor was studied in acetonitrile. Teteraaza Schiff bases are (Me4‐Bzo2[14]tetraeneN4) (tmtaa), (Me4‐4‐CH3Bzo2[14]tetraeneN4) (Metmtaa), (Me4‐4‐ClBzo2[14]tetraeneN4) (Cltmtaa), i.e., [(Me4‐Bzo2[14]tetraeneN4)] means that (5,7,12,14‐tetramethyldibenzo[b,i][1,4,8,11] tetraazacyclotetradecine) (tmtaa) and organotin(IV)chlorides are methyltin(IV) trichloride, phenyltin(IV)trichloride, dimethyltin (IV)dichloride, diphenyltin(IV) dichloride, and dibutyltin(IV)dichloride. The kinetic parameters and the second‐order k2 rate constants show the donor properties of tetraaza Schiff bases as Me4‐4‐CH3Bzo2[14]tetraeneN4 > Me4‐Bzo2[14]tetraeneN4 > Me4‐4‐ClBzo2[14]tetraeneN4 and also the acceptor properties of organotin(IV)chlorides as PhSnCl3 > MeSnCl3 > Ph2SnCl2 > Me2SnCl2 > Bu2SnCl2. An excellent linearity of kobs vs. the molar concentration of the acceptor, the high span of k2 values, the large negative values of ΔS≠, and the low ΔH≠ values suggest an associative (A) mechanism for the acceptor–donor interaction. © 2011 Wiley Peiodicals, Inc. Int J Chem Kinet 43: 247–254, 2011

Kinetics and mechanism of the ligand exchange reaction between tetradentate schiff base N,N'-ethylen-bis (salicylaldimine) and Ni(N,N'-propylen-bis(salicylaldimine))

“…26 These observations lead us to suggest a possible mechanism for the reaction when a Ni(salpn) complex reacts with H 2 salen ligand (Equations 10 and 11): is in agreement with a number of studies on the polydentate ligand exchange reaction. [5][6][7] The lone pairs electron on the phenolic oxygen atoms of H 2 salen provide a reasonable basis to propose the formation of adduct [Ni(salpn] . H 2 salen as the first step in the reaction.…”

“…1,3 Polydentate ligand exchange reactions are very interesting from a mechanistic point of view due to their importance in coordination chemistry. 4,5 However, the kinetics of polydentate ligands exchange reactions have not been studied in the same detail as monodentate ligands. In general, such systems proceed through intermediates, where the incoming polydentate ligand is partially coordinated and the leaving ligand is partially dissociated.…”

“…In general, such systems proceed through intermediates, where the incoming polydentate ligand is partially coordinated and the leaving ligand is partially dissociated. [5][6][7] The driving force for ligand exchange reactions in metal-complexes with polydentate ligands is the formation of a more stable complex. [8][9][10] The structures of the Ni(II) and Cu(II) complexes of multidentate ligands such as salen Schiff base ligands and its derivatives (Scheme 1) have been studied by various groups.…”