Structural Diversity of Alkaline Earth Centered Gold(I) Metallacoronates

Abstract

One‐pot reactions of the catechol‐scaffolding aroylbis(N,N‐diethylthiourea) H2Lcat with mixtures of alkaline earth nitrates M(NO3)2 (M2+ = Ca2+, Sr2+ or Ba2+) and (NEt4)[AuCl4] or [Au(tht)Cl] (tht = tetrahydrothiophene) in methanol in the presence of Et3N as supporting base give rise to neutral trinuclear gold(I) {2}‐metallacoronates with the composition of {M ⊂ [Au2(Lcat)2]} (1). Similar reactions with the pyridine‐centered aroylbis(N,N‐diethylthiourea) H2Lpy, however, produce complexes with the same metal‐to‐ligand ratio but with higher nuclearity {2M ⊂ [Au4(Lpy)4]} (2). In both 1 and 2, Au(I) ions are exclusively S‐bonded with the organic ligands and adopt a virtually linear coordination fashion. Such metal‐ligand binding is responsible for the formation of metallacoronands, which accommodate alkaline earth metal ions in their molecular voids, thereby resulting in host–guest coordination assemblies. The level of metal‐ligand aggregation in the resulting assemblies is dependent on the denticity, size and flexibility of the centered building block of the aroylbis(N,N‐diethylthiourea) ligands.

Gold(I) {2}‐Metallacoronates derived from a Catechol‐scaffolding Aroylbis(N,N‐diethylthiourea): Syntheses and Structures

“…The compositions and structures of the products are characterized by spectroscopic methods as well as X-ray structure determination. Assuming that the obtained products have the analogous composition with the M 2 + -containing compounds reported, [9]…”

“…The compositions and structures of the products are characterized by spectroscopic methods as well as X‐ray structure determination. Assuming that the obtained products have the analogous composition with the M 2+ ‐containing compounds reported, [9] cationic complexes {M⊂[Au 2 (L cat ) 2 ]} + (M 3+ =La 3+ ( 1 a ), Nd 3+ ( 1 b ), Yb 3+ ( 1 c ) or In 3+ ( 1 d )) could result from the assembly of the ligand, Au + and trivalent M 3+ ions. The assumption is strongly supported by mass spectrometry.…”

Gold-Based Coronands as Hosts for M3+ Metal Ions: Ring Size Matters

“…This is particularly useful when ligands have ‘hard’ and ‘soft’ donor atoms well separated in different positions of their scaffold. Such ligands can be designed on the basis of aroylthioureas, which represent in their most simple form, the benzoylthioureas (HL R ), a bidentate S , O chelator, which forms [M(L R ) 2 ] complexes (type I in Figure 1 ) with a large variety of transition metal ions [ 27 , 28 , 29 , 30 ]. It is interesting to note that corresponding bipodal phthaloylbis( N , N -dialkylthioureas) with two S , O chelating units form multinuclear assemblies with divalent metal ions such as Ni 2+ , Pt 2+ or Cu 2+ .…”

“…Particularly interesting bonding features are established with ‘soft’ metal ions such as Ag + or Au + , where no chelate formation was found, but a monodentate coordination to the sulfur atoms of the ligands is observed. As a result, macrocyclic, coronand-type ligands were formed, which can accommodate one or two alkaline earth metal ions [ 30 , 41 ]. The ready formation of such assemblies raises questions concerning the mechanism of their formation, the role of the (central) metal ion(s) and if the resulting ring size is exclusively determined by the used precursors H 2 L1 R or H 2 L2 R .…”

Ammonium‐Iron(III) metallacryptate inclusion complexes based on Aroylbis(N,N‐diethylthioureas): Synthesis and structure

“…Their bifunctional coordinative sites, namely the pyridine-or catechol-scaffolding block and the aroylthiourea moieties, enable heterotrinuclear complexes. [16][17][18][19][20][21][22] Some representatives are presented in figure 2. These trinuclear systems are topologically analogous with organic-based host-guest cryptates.…”