Cation- and Anion-Mediated Supramolecular Assembly of Bismuth and Antimony Tris(3-pyridyl) Complexes

Abstract

The use of antimony and bismuth in supramolecular chemistry has been largely overlooked in comparison to the lighter elements of Group 15, and the coordination chemistry of the tripodal ligands [Sb(3-py) 3 ] and [Bi(3-py) 3 ] (L) containing the heaviest p-block element bridgehead atoms has been unexplored. We show that these ligands form a common hybrid metal–organic framework (MOF) structure with Cu(I) and Ag(I) (M) salts of weakly coordinating anions (PF 6 – , SbF 6 – , and OTf – ), composed of a cationic substructure of rhombic cage (M) 4 (L) 4 units linked by Sb/Bi–M bonding. The greater Lewis acidity of Bi compared to Sb can, however, allows anion···Bi interactions to overcome Bi–metal bonding in the case of BF 4 – , leading to collapse of the MOF structure (which is also seen where harder metals like Li + are employed). This study therefore provides insight into the way in which the electronic effects of the bridgehead atom in these ligand systems can impact their supramolecular chemistry.

Highly Adaptive Nature of Group 15 Tris(quinolyl) Ligands─Studies with Coinage Metals

“…16,17 The coordination of the tris (3-pyridyl) and tris(4pyridyl) ligands to Cu and Ag salts gives extended structures involving a combination of N-donor and bridgehead-donor bonding (intermolecular coordination, Figure 1b). 18,19 Despite increasing interest in this area, the elaboration of this type of ligand using extended N-donor polyaromatic donor groups has been largely ignored as a means of modifying the coordination character. The first example of this type containing a heavier element bridgehead was MeSi(3-qy) 3 (qy = quinolyl), 20−22 effects and the geometric constraints imposed by the orientation of the donor quinolyl N atoms (Figure 1c).…”

“…Tripodal, facially coordinating tris (pyridyl) ligands have far-reaching applications in coordination, organometallic catalysis, and supramolecular chemistry. , The selection of the bridgehead atom and the position of the N-donor atoms in the pyridyl rings have a fundamental impact on the behavior and coordination properties of this family of ligands. , Classically, studies have focused on tris (2-pyridyl) ligands containing nonmetallic bridgehead atoms, E­(2-py) 3 (e.g., E = CR, COR, CH, N, P, PO; 2-py = 2-pyridyl) . However, incorporating heavier and more metallic main-group bridgehead atoms has been shown to provide an important tool for tuning the ligand character, enabling systematic modification of the bite angle, donor/acceptor properties, and reactivity. ,− Recent studies have explored the coordination chemistry of tris (2-pyridyl) ligands based on Sb and Bi, which coordinate metals (e.g., Cu + , Ag + , Li + ) through the three pyridyl arms in an N , N , N -chelate coordination mode, which is typical of the tris (2-pyridyl) family (intramolecular coordination, Figure a). , In addition, changing the position of the pyridyl N-donor atom from the 2- to the 3-position with respect to the bridgehead atom/group significantly changes the coordination behavior of the ligands, permitting the coordination of multiple metal centers. , The coordination of the tris (3-pyridyl) and tris (4-pyridyl) ligands to Cu and Ag salts gives extended structures involving a combination of N-donor and bridgehead-donor bonding (intermolecular coordination, Figure b). , …”

Structural and dimensional control of porphyrin capsules using Group 15 tris(3-pyridyl) linkers

“…We have very recently developed synthetic approaches to metallic or semi-metallic tris-pyridyl ligands, [42][43][44][45][46][47] including the heavier Group 15 ligands E(3-py) 3 [E = Sb (1), Bi (2)] (Fig. 2a), 48 and shown that the latter can be employed in the construction of a series of hybrid MOF arrangements with Cu + and Ag + (=M + ) salts, in which the ligands adopt a tetradentate N,N,N,E-bonding mode. 48 As shown in Fig.…”

“…2a ), 48 and shown that the latter can be employed in the construction of a series of hybrid MOF arrangements with Cu + and Ag + (=M + ) salts, in which the ligands adopt a tetradentate N,N,N,E-bonding mode. 48 As shown in Fig. 2b , these MOFs consist of E 4 M 4 cubane units in which the anions are encapsulated.…”

Base-Promoted Reactions of Organostibines with Alkynes and Organic Halides to Give Chalcogenated (Z)-Olefins and Ethers

“…Organostibines have gained great attention in the past decades and are widely used in Lewis acids, ligands, catalysts, and gas fixation . We are interested in C–C and C–Z (Z = O, S, Se N etc.)…”