Self‐Assembly in Gold(I) Chemistry: A Double‐Stranded Polymer with Interstrand Aurophilic Interactions

Abstract

There has been remarkable progress and interest in the design and synthesis of hybrid organic-inorganic molecular materials, and a key strategy is to design simple building blocks that can be induced to form complex molecular structures by selfassembly.[1] Gold(i) centers are particularly versatile as components of such building blocks based on their tendency for linear coordination, [2, 3] their high reactivity towards ligand substitution, [2] and their ability to form secondary aurophilic bonds that can be used to direct the self-assembly.[2-9] These properties have made it possible to design macrocycles, molecular triangles, catenanes, and polymers with gold(i) centers coordinated to a phosphane and a nitrogen or carbon donor ligand. [2][3][4][5][6][7][8][9][10] The gold-carboxylate linkage is important in self-assembled monolayers on gold colloids [11] and is well known in simple complexes, [2,12] but it has not yet been exploited in molecular materials. Here we show that a simple condensation procedure can lead to the self-assembly of a cyclic dimer or trimer, or of a linear polymer for gold(i) complexes of the three isomers of diphenylphosphanylbenzoic acid, and that the polymer forms a remarkable doublestranded structure through aurophilic attractions. The ligands themselves are already known to give interesting gold compounds [13,14] and bimetallic compounds, [15] and this work further highlights their potential in the field of hybrid organic-inorganic molecular materials. The synthetic strategy was to eliminate HCl from the ortho (1), meta (2), and para (3) isomers of [AuCl(Ph 2 PC 6 H 4 -CO 2 H)], [13,14] to yield the corresponding oligomers or polymers [{Au(Ph 2 PC 6 H 4 CO 2 )} n ], with the expectation that the degree of aggregation would be different for the different isomers. Preliminary experiments with [AuCl(4-Ph 2 P-C 6 H 4 CO 2 H)] (3), which forms a hydrogen-bonded dimer in the solid state (Figure 1), were unsuccessful since the complex was resistant to dehydrochlorination with mild bases and was decomposed by stronger ones. However, success was achieved by a two-step reaction involving abstraction of the chloride ligand from each complex 1-3 using silver(i) trifluoroacetate to form the corresponding gold(i) trifluoroacetate complex, which was not isolated but was treated in situ with a base to eliminate trifluoroacetic acid and give the product, as outlined in Scheme 1. Complex 1 gave a mixture of dimer 4 and trimer 5, while complex 2 gave only a molecular triangle 6, and complex 3 gave an insoluble polymer 7.The soluble complexes 4-6 were characterized in solution by NMR spectroscopy and ESI mass spectrometry. Complex 6 gave a singlet in the 31 P NMR spectrum (in CDCl 3 ) at d = 28.8 ppm and a peak at m/z = 1639 in the ESI-MS (in CH 2 Cl 2 /CH 3 CN, with CsI present to enhance ionization), which corresponds to the [{Au(Ph 2 PC 6 H 4 CO 2 )} 3 ]·Cs + ion, and indicates the presence of the molecular triangle structure only. Complexes 4 and 5 formed an equilibrium mixture in solution. Thus, t...

Small Metal‐Containing Oligomers Using M2(dmpm)x and M2(dmb)y Luminescent Building Blocks (M = Cu, Ag; x = 2, 3; y = 1, 2)

“…The Cu···Cu separation is found to be 4.011 Å , where no Cu···Cu interaction is noted. The structure exhibits similarities with the d 10 -d 10 complex Pt 2 (dppm) 3 (PPh 3 ), [37] in which one Pt atom adopts a tetracoordinate geometry causing an increase in the Pt···Pt distance with respect to Pt 2 (dppm) 3 with the difference that one diphosphane ligand is replaced by two isocyanide groups.…”

“…The corresponding Ag 2 (dmpm) 3 2ϩ complex does not react with dmb even in excess. This behavior may reflect the fact that dmpm is a strong σ-donor, which renders the Ag I atoms significantly more electron-rich.…”

“…The X-ray structures for the M 2 (dmpm) 3 2+ (M = Cu, Ag) and Cu 2 (dmpm) 3 (CN-tBu) 2 2+ complexes, XRD patterns (X-ray powder diffraction), DSC (differential scanning calorimetry), TGA (thermal gravimetric analysis), and the solid-state IR spectra have been examined in order to characterize these complexes and oligomers. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) works on the {Pd 4 (dmb) 4 (dmb) 2ϩ } n [6] and {Pt 4 (dmb) 4 -(diphos) 2ϩ } n [7] polymers [diphos ϭ Ph 2 P(CH 2 ) m PPh 2 ; m ϭ 4Ϫ6; 84000 Ͻ MW n Ͻ 307000; Scheme 2].…”

A Microporous 1D Heterometallic Coordination Polymer Based on Phosphine–Ag5Cl4 Saddle Unit

“…In continued attempts to form polymers by self-assembly, a number of phosphine-based supramolecular polymers have been explored [10][11][12][13][14][15]. Hydrogen-bonded supramolecular polymers have been obtained based on hybrid phosphine ligands [16][17][18].…”

Synthesis of a serious of copper(II)-pyrazolyl complexes in different solvents and anions

“…Recent interest in copper-pyrazolyl complexes has been aroused by its resemblance to active sites in some copper-containing metalloproteins and its catalytic properties towards cyclopropanation and aziridination metalloproteins [2] or as the precursors for the syntheses of various multinuclear model complexes [3]. On the other hand, molecular self-assembly based on the principle of crystal deign and engineering has proved to be efficient for the formation of intriguing structural diversities and potential applications in supramolecular chemistry and material chemistry [4][5][6]. However, the mechanism of molecular self-assembly is still unclear, and the predictability and tunability of exact structures of the assembly products are difficult [7].…”