Recent Trends in Group 11 Hydrogen Bonding

Conventional hydrogen bonding (H-bonding) has been extensively studied in organic and biological systems. However, its role in transition metal chemistry, particularly with Group 11 metals (i.e. Cu, Ag, Au) as hydrogen bond acceptors, remains relatively unexplored. Through a combination of experimental techniques, such as Nuclear Magnetic Resonance (NMR), Infrared spectroscopy (IR), X-Ray Diffraction (XRD), and computational calculations, several aspects of H-bonding interactions with Group 11 metals are examined, shedding light on its impact on structural motifs and reactivity. These include bond strengths, geometries, and effects on electronic structures. Understanding the intricacies of hydrogen bonding within transition metal chemistry holds promise for various applications, including catalytic transformations, the construction of molecular assemblies, synthesis of complexes displaying anticancer activities, or luminescence applications (e.g. Thermally Activated Delayed Fluorescence, TADF). This review encompasses the most significant recent advances, challenges, and future prospects in this emerging field.

Silver-based Terpyridine Complexes as Antitumor Agents

Silver complexes bearing substituted terpyridine or tetra-2-pyridinylpyrazine ligands have been prepared and structurally characterised. The study of the anticancer properties of silver complexes with this type of ligands is scarce, despite the possibilities of combining the properties of the metal and the ability of the ligands for DNA binding. Here, the antiproliferative activity, stability, CT-DNA binding and mechanism of cell death of these types of derivatives are studied. High cytotoxicity against different tumour cells was observed, and, more important, a great selectivity index has been detected between tumour cells and healthy Lymphocytes T for some of these compounds. The CT-DNA interaction study has shown that these derivatives are be able to interact with CT-DNA via moderate intercalation. Furthermore, cell death studies indicate that these derivatives promote the apoptosis via mitochondrial pathway.

New palladium(II) and platinum(II) complexes with 9-aminoacridine: structures, luminiscence, theoretical calculations, and antitumor activity

The new complexes [Pd(dmba)( N10-9AA)(PPh 3)]ClO 4 ( 1), [Pt(dmba)( N9-9AA)(PPh 3)]ClO 4 ( 2), [Pd(dmba)( N10-9AA)Cl] ( 3), and [Pd(C 6F 5)( N10-9AA)(PPh 3)Cl] ( 4) (9-AA = 9-aminoacridine; dmba = N,C-chelating 2-(dimethylaminomethyl)phenyl) have been prepared. The crystal structures have been established by X-ray diffraction. In complex 2, an anagostic C-H...Pt interaction is observed. All complexes are luminescent in the solid state at room temperature, showing important differences between the palladium and platinum complexes. Complex 2 shows two structured emission bands at high and low energies in the solid state, and the lifetimes are in agreement with excited states of triplet parentage. Density functional theory and time-dependent density functional theory calculations for complex 2 have been done. Values of IC 50 were also calculated for the new complexes 1- 4 against the tumor cell line HL-60. All of the new complexes were more active than cisplatin (up to 30-fold in some cases). The DNA adduct formation of the new complexes synthesized was followed by circular dichroism and electrophoretic mobility. Atomic force microscopy images of the modifications caused by the complexes on plasmid DNA pB R322 were also obtained.

Heteropolynuclear phosphide complexes: phosphorus as unique atom bridging coinage metal centres

In this paper we describe the synthesis and reactivity of the diphenylphosphine derivatives [Au(C6F5)(PPh2H)] and trans-[Au(C6F5)2(PPh2H)2]ClO4. Reactions of the latter or the neutral [Au(C6F5)3(PPh2H)] with the appropriate Group 11 metal reagents (M = Au, Ag, Cu) in the presence of acetylacetonate afford a series of novel Au(III)-M phosphido-bridged complexes, which have been scarcely represented to date. The crystal structure of the tetranuclear [(Au(C6F5)2(mu-PPh2)2Ag)2] and the dinuclear [Au(C6F5)3(mu-PPh2)M(PPh3)] (M = Au,Ag) complexes were established by X-ray diffraction methods. The synthesis and deprotonating activity of the anionic gold(III) complex PPN[Au(C6F5)3(acac)] (PNN = [N(PPh3)2]+) was studied.

Experimental and theoretical studies of the d8-d10 interaction between Pd(II) and Au(I): bis(chloro[(phenylthiomethyl)diphenylphosphine]gold(I))- dichloropalladium(II) and related systems

The reaction between thioether phosphine gold(I) precursors such as [AuCl(Ph2PCH2SPh)], 1, or [Au(Ph2PCH2SPh)2]CF3SO3 and PdCl2(NCPh)2 affords the new compounds [(AuCl(Ph2PCH2SPh)2PdCl2], 2, and [AuPdCl2(Ph2PCH2SPh)2]CF3SO3, 3. The crystal structure of complex 2 has the sterically unhindered Pd(II) and Au(I) at a distance of 314 pm. Quasirelativistic pseudopotential calculations on [AuPdCl3(PH2CH2SH)(SH2)] models give short Au-Pd distances at the second-order Møller-Plesset (MP2) level and long Au-Pd distances at Hartree-Fock (HF) level. A detailed analysis of the Au-Pd interaction shows dominant dispersion, some ionic contributions, and no net charge transfer between the metals.

Synthesis, structure, luminescence, and theoretical studies of tetranuclear gold clusters with phosphinocarborane ligands

Treatment of the tetranuclear gold cluster [Au4((PPh2)2C2B9H10)2(AsPh3)2] (1), which contains the nido-carborane-diphosphine [7,8-(PPh2)2C2B9H10]-, with various tertiary phosphines leads to derivatives [Au4((PPh2)2C2B9H10)2-(PR3)2] (PR3 = PPh3 (2), P(4-MeC6H4)3 (3), P(4-OMeC6H4)3 (4)). The X-ray crystal structure of complex 4 shows a tetrahedral framework of gold atoms, two of which are chelated by the diphosphine, and two are coordinated to one monophosphine ligand each. These compounds are very stable and are obtained in high yield. MP2 calculations suggest that the two types of chemically nonequivalent gold atoms can be formally assigned as Au(I) (those attached to the arsines or phosphines) and Au(0) (those bonded to the anionic diphosphine) and emphasize the role of correlation in the gold-gold interactions. The compounds are luminescent. The emission is assigned to a gold-centered spin-forbidden transition; the assignment of the oxidation state of the gold centers on this basis leads to results coincident with those obtained by theoretical calculations.

The elusive structures of pentakis[(triphenylphosphine)gold]ammonium(2+) bi

[Pentakis[(triphenylphosphine)gold(I)]ammonium(2+)] bis[(tetrafluoroborate)(1-)] was prepared from [tetrakis[(triphenylphosphine)gold(I)]-ammonium(1+)] [tetrafluoroborate(1-)] and [(triphenylphosphine)gold(I)] tetrafluoroborate in hexamethyl phosphoric triamide and tetrahydrofuran at 20 degrees C in 53% yield and crystallized from dichloromethane as the new solvate [[(Ph3P)Au]5N]3 [BF4]6 [CH2Cl2]4. The crystal structure of this product has been determined by single-crystal X-ray methods [monoclinic, P2(1/n), a = 34.200(3), b = 15.285(1), c = 53.127(3) A, beta = 107.262(2) degrees, V = 26521(3) A3, Z = 12, at 153 K]. The lattice contains three independent trinuclear dications that have no crystallographically imposed symmetry and are mutually similar in their molecular structure. The geometry of the [Au5N] core with pentacoordinate nitrogen atoms is intermediate between trigonal-bipyramidal and square pyramidal with severe distortions to minimize the Au-Au distances along some of the edges of the polyhedra. The three structures are thus different from that found previously in the tetrahydrofuran solvate [[(Ph3P)-Au]5N](BF4)2(C4H8O)2, where the geometry of the same trinuclear dication is closer to the trigonal-bipyramidal reference model. The new results are discussed in the light of the structures of tetra(gold)ammonium cations in salts of the type [[(Ph3P)Au]4N]+X- and of related tetra-, penta-, and hexacoordinate poly(gold)phosphonium, -arsonium, -sulfonium, and -selenonium cations.