An Excursion into the Intriguing World of Polymeric Tl(I) and Ag(I) Cyanoximates

Abstract

Abstract:The reaction of hot (~95 °C) aqueous solutions of Tl 2 CO 3 with solid HL (HL = NC-C(=N-OH)-R is a cyanoxime, and R is an electron-withdrawing group; 37 ligands are known up-to-date) leads to crystalline yellow/orange TlL. Similarly, the reaction between AgNO 3 and ML (M = K + , Na + ; L = anion of the monodeprotonated cyanoxime) this time at room temperature in mixed ethanol/aqueous solutions leads to sparingly soluble, colored AgL in high-yield. All synthesized monovalent Tl and Ag complexes were characterized using a variety of spectroscopic methods and X-ray analysis, which revealed the formation of primarily 2D coordination polymers of different complexity. In all cases cyanoxime mono-anions act as bridging ligands. Thallium(I) cyanoximates adopt in most cases a double-stranded motif that is originated from centrosymmetric (TlL) 2 dimers in which two Tl 2 O 2 rhombs are fused into infinite "ladder-type" structure. There are very short (3.65-3.85 Å) intermetallic distances in (TlL) n , which are close to that (3.46 Å) in metallic thallium. This opens the possibility for the electrochemical or chemical generation of mixed valence Tl(I)/Tl(III) polymers that may exhibit electrical conductivity.

Zinc Complexes with Cyanoxime: Structural, Spectroscopic, and Catalysis Studies in the Pivaloylcyanoxime–Zn System

“…There are only two reports containing preparation and some properties of Zn-cyanoximates, , but no crystallographic characterization was carried out. Cyanoximes represent an important subclass of oximes that has received intense studies in the last decades because of their greater acidity, diversity of donor atoms for metal ions binding, and, subsequently, excellent properties as polydentate ligands . Complexes of cyanoximes exhibited a variety of practically interesting properties .…”

“…Thus, the Tl + and Ag + PiCO-based complexes have been structurally characterized before. The crystal structure of the Ag-PiCO compound is a layered 2D coordination polymer where the PiCO – anion displayed bridging mode between four different silver­(I) atoms, while the crystal structure of Tl–PiCO complexes have been reported as coordination polymer with three different binding modes of the PiCO – anion. ,, …”

Polymeric Composites with Silver (I) Cyanoximates Inhibit Biofilm Formation of Gram-Positive and Gram-Negative Bacteria

“…Crystal structures of several AgL we previously reported [43,47]. These compounds are mostly 2D-coordination polymers (with the exception of Ag(CCO), which forms 3D-network [47] containing nitroso-anions that form bridges of different complexity [42]. Also, we had determined crystal structures for both yellow and red polymorphs of the Ag(PiCO).…”

“…Preparation of twelve Silver(I) complexes of 1:1 composition that include cyanoxime anions was accomplished using a modified straightforward one-pot two steps reaction [42,43,44,47,48]. Thus, the deprotonated cyanoxime, obtained upon the addition of K 2 CO 3 to the HL (Scheme 1) forming bright-yellow solution in water, received an aqueous solution of AgNO 3 , which was added dropwise at room temperature and intense stirring: (a) 2 HL + K 2 CO 3 = 2 KL + H 2 O + CO 2 ↑ and (b) KL + AgNO 3 = AgL ↓ + KNO 3 .…”

“…The latter include growth-regulating [37,38] and antimicrobial [39,40,41] properties. We initiated synthesis and characterization of structures and properties of the new family of silver cyanoximates (reviewed in Reference [42]) and performed a preliminary assessment of their antimicrobial activity [43], followed by their further detailed characterization [44]. In the most recent work, we obtained two previously unknown AgL (L = 2-oximino-2-cyano-N-morpholylacetamide, MCO- and 2-oximino-2cyano-N-piperidineacetamide, PiPCO-), which were added to the list of visible light and heat stable, poorly water soluble antimicrobial compounds [45].…”