Unique Pt5 metallacycle: [PtIICl(pyrrolidinedithiocarbamate)]5

Abstract

The neutral complex [PtCl(PyDT)] 5 (PyDT = (CH 2 ) 4 NCS 2 -) represents the first example of a Pt 5 metallacycle. This unique architecture based on chiral S-bridged Pt II monomers was prepared by thermal degradation of the reaction product of PtCl 2 and a pyrrolidinedithioester.Dithiocarbamate complexes of transition metals have been widely studied, 1 focusing mainly on their antitumoral properties and flexible possibilities for molecular architectures. Due to their extremely versatile and robust motif, dithiocarbamates have been utilized for metal-directed self-assembly, 2 and more recently for the stabilization of gold nanoparticles.3 They are well-known chemoprotective agents against heavy metal intoxication, 4 particularly against cisplatin, 5 the most prolific antitumoral drug. Recent tendencies aiming to reduce the toxicity of antitumoral drugs require the design of new molecules based on either nitrogen (analogue to cisplatin) or sulfur donor atoms (as carbamates).6 Interesting results were obtained with Pt II , Pd II and Au III compounds with ethylsarcosinedithio-and dimethyldithiocarbamates as ligands. 7Complexes containing pyrrolidinedithiocarbamate (PyDT) are under investigation in order to develop potential antitumoral drugs, with Ru(III) complexes being the most active. 8The versatility of dithiocarbamates for molecular architectures lies in their ability to coordinate metals in different modes (Chart 1): as (i) monodentate ligands, involving one of the sulfur atoms, as (ii) bidentate ligands, with both donor S atoms coordinated to the same metal (as chelate) or to different (as bridging S) metals, and combining both modes, as (iii) tridentate and even (iv) as tetradentate ligands (Chart 1). The combination of such flexible ligands with the binding possibilities of transition metals results in a multitude of mono-and multinuclear, discrete and polymeric constructs. 9Here, we report the first example of a Pt 5 metallacycle, extending the existing series of platinum (Pt 2 , Pt 3 , Pt 4 and Pt 6 ) metallacycles. are not as common as other metallastructures, such as triangles, squares, hexagons or macrocycles. 11The reaction of PtCl 2 with pyrrolidinedithioester (PyDTM) yields [PtCl 2 (PyDTM)] (1), which after thermal degradation (220 • C) 6 produces [PtCl(PyDT)] 5 (2) (PyDT = pyrrolidinedithiocarbamate) (Scheme 1a). Crystals were grown by the slow evaporation of 2 in dichloroethane, crystallizing with two molecules of solvent. § Dithiocarbamate complexes of general formula [MCl(RDT)] n can be stabilized by halogen (M = Pd; n = 2) 12 or sulfur (M = Pd, Pt; n = 2, 3) 13 bridging ligands. Scheme 1The metallacyclic structure of complex 2 is assembled from five chiral PtCl(PyDT) units (Fig. 1c). The PyDT moieties act as tridentate ligands, both chelating Pt and bridging the platinum This journal is

Synthesis, characterization and cytotoxic activity of palladium (II) dithiocarbamate complexes with α,ω-diamines

“…In the [PdCl(mercaptonicotinic acid)] 3 species the single PdCl(mercaptonicotinic) units, in which the anion is S,N chelated to the metal, form a trimeric molecule held by sulfur bridges, the chlorine atoms being terminal [43]. An unique and exotic pentanuclear Pt 5 structure has been recently reported by the author where S atoms of PyDT ligands act as chelating and bridging donors at the same time [44].…”

Neutral discrete metal–organic cyclic architectures: Opportunities for structural features and properties in confined spaces

“…The versatility of dithiocarbamates lies in their ability to coordinate metal ions in different modes to afford discrete architectures [284]. The reaction of PtCl 2 with pyrrolidinedithioester (L143, PyDTM) afforded monometallic complex, [PtCl 2 (L143)], followed by the thermal degradation at 220 • C generated [PtCl(PyDT)] 5 (179) (Scheme 69) with two possible enantiomers ( , , , , and , , , , ) based on chiral S-bridged Pt II monomers [285].…”

“…The origin of the chirality of the monomer arose from the orientation of the linked platinum atom (Pt ) of a vicinal monomer, which can be Scheme 69. Preparation of compound 179 [285]. situated either above ( ) or below ( ) the coordination plane of the platinum atom of the monomer and, hence, two enantiomers ( , , , , and , , , , ) were possible, based on chiral Sbridged Pt II monomers.…”

“…Three different perspectives of complex 179: (a) detail of the chirality of the monomer; (b) schematic view of the envelope conformation and (c) molecular structure[285].…”

Fluorescent sensing of monofunctional platinum species

“…[21][22][23][24] FDCPt1 was synthesised in two steps from fluorescein (Scheme 1), first with amidation in hydrazine to give the fluorescein hydrazide. This intermediate was heated in the presence of carbon disulfide and potassium hydroxide.…”