Synthesis, crystal structure, theoretical calculations and antimicrobial properties of [Pt(tetramethylthiourea)4] [Pt(CN)4]·4H2O

• The synthesis and crystal structure of [Pt(Tmtu)4][Pt(CN)4] is presented.
• Homodromic H-bonds of four H2O molecules per unit cell determine a 2D-network.
• Complex [Pt(Tmtu)4][Pt(CN)4] is moderately active against some microorganisms.
• Possible intermediacy of [Pt(Tmtu)2(CN)2)] is evaluated by DFT calculations.
• Complex [(Tmtu)2Pt(μ2-CN)(μ2-η2-CN)Pt(Tmtu)(CN)]CN was identified and characterized.

A new platinum(II) complex, [Pt(Tmtu)4][Pt(CN)4]·4H2O (1) was synthesized by reaction of K2[PtCl4], KCN and tetramethylthiourea (Tmtu). Its structure was determined by X-ray crystallography. The [Pt(CN)4]2− anion shows regular square planar geometry at platinum, while in the [Pt(Tmtu)4]2+ cation the geometry at platinum is somewhat distorted. Hydrogen bonding between water molecules and the cyanide nitrogen of [Pt(CN)4]2− ions stabilizes the structure and leads to a supramolecular 2D network. DFT calculations support the experimentally found dinuclear (homocoordinated) ion-pair structure 1 as the most stable in comparison to noncovalent dimer [Pt(CN)2(Tmtu)2]222 that could, in turn, be involved in the formation sequence of 1. Antimicrobial activities of the complex were evaluated by minimum inhibitory concentration and the results showed that the complex exhibited moderate activities against gram-negative bacteria (Escherichiacoli, Pseudomonas aeruginosa) and molds (Aspergillus niger,Penicilliumcitrinum).

A new dinuclear platinum(II) complex formed by a [Pt(Tmtu)4]2+ cation (Tmtu = tetramethylthiourea) and a [Pt(CN)4]2− anion is described and its higher stability with respect to a dimeric heterocoordinated [Pt(Tmtu)2(CN)2)] species computationally evaluated.Figure optionsDownload as PowerPoint slide