Stable, Water‐Soluble Pta‐Based Ru–Ag Organometallic Polymers

Abstract

One of the latest trends in supramolecular chemistry is the quest for reproducible methods to achieve controlled selforganization of discrete units to form homo-and heterometallic coordination networks, aggregates, and polymers.[1] This development is based on the use of appropriate organic, inorganic, and organometallic building blocks that allow the synthesis of 1D linear or twisted chains, 2D squares and polygons, and 3D cubes and polyhedra.[2] Among the organic spacers, nitrogen-based aromatic heterocycles are the most widely used due to their good donor properties and rigidity. These ligands can act as corner units (bipy, phen) [3] and spacers (pyrazines, [4] terpy, [5] porphyrinates, [6] tetraazamacrocycles [7] ). P-donor ligands as spacers have received less attention:[8] P 2 and P 5 ligands have been studied by Scheer and co-workers, [9] whereas the use of multidentate phosphanes has been reviewed recently.[10] To the best of our knowledge, the use of mixed N,P ligands as metal-coordinating spacers has not been reported to date.Very few coordination polymers are water soluble, an example being the poly(ferrocenylsilane)-b-poly(aminomethacrylate) copolymer recently described by Manners and coworkers [11] as part of their ongoing study on metallocenebased polymers, [12] which can be prepared by ring-opening polymerization to afford either macromolecules with pendant ferrocenyl substituents in the polymer side chains [13] or poly(ferrocenylsilane)s. [14] Other examples of ligands that afford coordination polymers with various topologies and applications are ferrocenyl ligands bearing bipyridines [15] or carboxylates.[16]Herein we describe the first known case of a watersoluble, air-stable, heterobimetallic polymeric structure based on two metal-containing moieties ([CpRu] + and [AgCl 2 ] À ) bridged by a cagelike, water-soluble monodentate phosphane, 1,3,5-triaza-7-phosphaadamantane (pta), in an unprecedented N,P coordinating mode.We recently reported the synthesis and characterization of the water-soluble cyclopentadienylruthenium complex [CpRuCl(pta) 2 ] (1), which is stabilized by the phosphaadamantane-like pta ligand, and described its catalytic and biological properties.[17] As part of our studies on new water-soluble organometallic derivatives based on the [CpRu(pta) 2 ] + moiety, [18] we treated 1 with one equivalent of AgOTf (OTf = OSO 2 CF 3 ) in DMSO to remove the chloro ligand. Unexpectedly, no AgCl precipitated from the resulting orange solution, and neither did it contain the expected product [CpRu(OTf)(pta) 2 ] (2), which was obtained by treatment of 1 with TlOTf. [19] Intrigued by this apparently odd result, we repeated the experiment in an NMR tube.31 P{ 1 H} NMR analysis in [D 6 ]DMSO indicated the formation of a 1:1 mixture of the new complex [CpRu(pta) 2 (dmso-kS)]OTf (3; singlet at d = À28.13 ppm) and the bimetallic neutral coordination polymer [{CpRu(pta) 2 (dmso-kS)}{AgCl 2 }] ¥ (4; singlet at d = À23.19 ppm), as shown in Scheme 1.Quantitative formation of 4 could be attained by ...

Synthesis, Reactivity, X‐ray Crystal Structures and Electrochemical Behaviour of Water‐Soluble [Tris(pyrazolyl)borato]ruthenium(II) Complexes of 1,3,5‐Triaza‐7‐phosphaadamantane (PTA)

“…Their solubility in common solvents depends strongly on the nature of the phosphanes contained in the complexes. Thus, 2 is soluble in most common polar organic solvents but only slightly soluble in water (S 25°C = 2.1 mg mL -1 ), whereas replacement of the second PPh 3 [19] has also been reported. Quantitative formation of the same aquo cation takes place at 60°C upon mixing D 2 O solutions of TlPF 6 and 3 (NMR-tube experiment).…”

Gold(I) and Palladium(II) Thiolato Complexes Containing Water‐Soluble Phosphane Ligands

“…[10][11][12][13] A review and recent reports of new coordination modes of this ligand illustrate the rich and varied coordination chemistry displayed by this compound. [13][14][15][16] The diacetate derivative of PTA known as DAPTA has only been reported recently [17] and to date only a very limited number of complexes with this ligand have been described. [11,17] In this paper we report the synthesis and structures of some water-soluble gold(I) and palladium(II) complexes containing PTA and DAPTA with various thiolato ligands.…”

Boron–Nitrogen Adducts of 1,3,5‐Triaza‐7‐phosphaadamantane (PTA): Synthesis, Reactivity, and Molecular Structure

“…PTA coordinates to metal atoms through the phosphorus atom, with only one known example of a PTA complex containing a nitrogen-metal dative bond; a polymeric structure formed through the coordination of a nitrogen of a ruthenium-bound PTA ligand to silver. [9] Because metals preferentially bind to the phosphorus of PTA, the amine functionalities of PTA are the preferred site of alkylation and protonation. [7,10] We have been interested in the coordination chemistry of PTA and, specifically, why transition metals bind to the phosphorus site and other Lewis acids, such as H + and R + , bind preferentially, although not exclusively, to the nitrogen sites.…”