Platinum assisted cyclization of S-methyl 3-acyl-2-methyldithiocarbazates under mild conditions. Crystal structure of [Pt2(μ-SMe)(terpy)2][ClO4]3 †

Abstract

The reaction of the newly synthesized aqua complex [Pt(terpy)(OH 2 )][BF 4 ] 2 with S-methyl 3-acyl-2-methyldithiocarbazates under a variety of experimental conditions has been studied. Using a 2 : 1 metal to ligand ratio in methanol, a platinum assisted cyclization was observed. The reaction products were ∆ 2 -1,3,4-oxadiazoline-5-thione derivatives and the binuclear tricationic complex [Pt 2 (µ-SMe)(terpy) 2 ] 3ϩ whose molecular structure has been determined by X-ray crystallography. This platinum assisted transformation is proposed as a new synthetic route to ∆ 2 -1,3,4-oxadiazoline-5-thiones under mild conditions. In the presence of an excess of a non-co-ordinating acid (HClO 4 , CH 3 SO 3 H or CF 3 SO 3 H) the cyclization is completely quenched and complexes with co-ordinated S-methyl 3-acyl-2-methyldithiocarbazates have been isolated. A general mechanism which accounts for the observed transformations is proposed on the basis of 1 H NMR and UV/Vis evidence.

The Relative Coordinating Ability of Some Weak O‐Donor Anions and Water Towards the [Pt(terpy)]2+ (terpy = 2,2′:6′,2″‐terpyridine) Center – X‐ray Crystal Structures of [Pt(terpy)(H2O)](CF3SO3)2 and [Pt2(μ‐OH)(terpy)2](PF6)2(CF3SO3)

“…These distortions are associated with a significant shortening of the Pt-N2 distance [1.914(4) Å] with respect to the Pt-N1 and Pt-N3 ones [2.021(5) and 2.009(4) Å, respectively], in agreement with the geometries observed in similar complexes of Pt II with ter-or tetradentate ligands. [18][19][20][21][22][23] The three coordinated terpy nitrogen atoms, the platinum atom, and the water oxygen atom lie approximately in the same plane with maximum deviations from this plane for O1 of 0.033 (5) basal plane and is linked to the oxygen atoms of two triflate anions by hydrogen bonds. The Pt-OH 2 distance [2.040(5) Å] compares well with the distances observed in Pt II square-planar complexes where a water molecule is trans to a nitrogen atom (range: 2.05-2.10 Å).…”

Kinetic and mechanistic investigation into the influence of chelate substituents on the substitution reactions of platinum(II) terpyridine complexes

“…The steric strain on [Pt(terpy)X] (2− n )+ type complexes is also another reason for the high reactivity 17. Therefore, a vast number of studies have been done on the kinetics of substitution of [Pt(terpy)X] n + ‐type complexes with various nucleophiles 8,13,14,17–33. In terms of their biological properties, these Pt(II) terpy complexes themselves have also been shown to bind to double‐stranded DNA through intercalation 34 and have been found to be cytotoxic against Trypanosoma and Leishmania parasites in addition to human ovarian carcinoma 35,36.…”

Controlling the Lability of Square-Planar PtII Complexes through Electronic Communication between π-Acceptor Ligands

“…N ‐(pyridyl‐2‐methyl)‐1,2‐diaminoethane was synthesized according to the literature method,11a whereas 2,6‐bis(aminomethyl)pyridine was prepared following a method used to synthesize 6‐(aminomethyl)‐2,‐2′‐bipyridine by using 2,6‐bis(bromomethyl)pyridine as starting material 11b,11c. Synthesis of aaa and ppp was performed according to literature methods 11d,11e. The preparation of the chloroplatinum precursor for pap, aap , and apa was performed according to a procedure similar to that used for the preparation of the chloro complex of ppp 11f.…”