Yue-Jian Lin

Iridium-Mediated Regioselective B–H/C–H Activation of Carborane Cage: A Facile Synthetic Route to Metallacycles with a Carborane Backbone

One-pot reactions of carborane carboxylic acids (L), [Cp*IrCl2]2, and silver salt are reported, which lead to regioselective B-H or C-H bond activation at ambient temperature in good yields. This process is demonstrated for three carborane (o-, m-, p-) dicarboxylates, and metal-mediated B-H functionalization of a p-carborane derivative is accomplished for the first time. Two metal-induced self-assembly routes to tetra-nuclear metallacycles 3 and 5 were performed through B(4, 7)/H and B(2, 10)/H activation, respectively, and the two metallacycles were found to be stable and to exist in solution as discrete complexes. Different activation modes in the carborane cage were ascribed to the characteristic structure of the products and the electronic density differences. The analogous reaction of o-carborane monocarboxylate with the same metal precursor gave the C-H activation complex 6, indicating that the B-H bond is more stable than the C-H bond in this carborane cage. The selective activation was confirmed by DFT calculation results. In this study, a facile and efficient synthetic route has been developed through specific B-H bond activation to construct carborane-based metallacycles that are unavailable by conventional methods.

Stepwise Construction of Discrete Heterometallic Coordination Cages Based on Self-Sorting Strategy.

A chelation-directed self-sorting synthesis of a series of cationic heterometallic coordination cages (HCCs) with tunable sizes is described. Two complexation modes were found in the cage-forming process. Metal-anchoring host-guest behavior and size-selective in-cage catalytic activities were found for the HCCs.

Self‐Assembly of Molecular Borromean Rings from Bimetallic Coordination Rectangles

In contrast to conventional stepwise synthesis of molecular Borromean rings, a self-assembly synthetic method which proceeds without the aid of a template has been developed. In the formation of molecular rectangles, by adjustment of the long-arm length of the rectangles, a series of size-dependent Borromean-link frameworks were constructed. Both the shortest length of two arms and the relative proportion of the length of the long arm to that of the short arm play a key role in the formation of Borromean rings. DFT calculations were used to provide theoretical support for the formation of discrete interlocked frameworks.

Stepwise formation of “organometallic boxes” with half-sandwich Ir, Rh and Ru fragments

Octanuclear complexes with half-sandwich Ir, Rh and Ru fragments and tetra(4-pyridyl)porphyrin (L1) and oxalate (L2) spacer ligands [(Cp*M)4L1]2[L2]4 (M = Ir (6a) M = Rh (6b)), [((cymene)Ru)4(L1)]2[L2]4 were prepared and characterized.

Two-step assembly of multinuclear metallacycles with half-sandwich Ir, Rh, and Ru fragments for counteranion encapsulation.

Two-step reactions of [Cp*M(mu-Cl)Cl](2) (M = Ir, Rh) and [(p-cymene)Ru(mu-Cl)Cl](2) with first AgOTf or AgPF(6) and then pyridyl-substituted dionate ligands [3-(4-pyridyl)pentane-2,4-dione (L(1)), 1-(4-pyridinyl)butane-1,3-dione (L(2)), 1-(3-pyridinyl)butane-1,3-dione (L(3))] resulted in the formation of the hexanuclear 48-membered metallacycles [(Cp*Ir)(L(1))](6) x (OTf)(6) (1) and [(Cp*Rh)(L(1))](6) x (OTf)(6) (2), the tetranuclear 28-membered metallacycle [(Cp*Ir)(L(2))](4) x (OTf)(4) (3), and the 24-membered metallacycle [(p-cymene)Ru(L(3))](4) x (OTf)(4) (4), as well as the hexanuclear 48-membered metallacycles {[(p-cymene)Ru(L(1))](6)(OTf)} x (OTf)(5) (5) and {[(p-cymene)Ru(L(1))](6)(PF(6))} x (PF(6))(5) (6) showing encapsulation of the counteranions. Compounds 1-6 were characterized by single crystal X-ray analyses and revealed that these metallacycles constructed from half-sandwich metal corners and pyridyl-substituted diketone linkers formed large ring structures. In addition, when the couteranions of 5 and 6 were exchanged, the shapes and sizes of the host units [(p-cymene)Ru(L(1))](6)(6+) underwent some self-adjustment to allow for accommodation of the different anionic guests. Weak hydrogen bonding of the type C(S)-F(O)...H-C(sp(3)) and P-F...H-C(sp(3)) and electrostatic interactions are considered the basic forces to establish the metallacyclic units in 5 and 6 with anion encapsulation. The found variation in the metallacyclic geometries was explained on the basis of a structural flexibility of the corner fragments, subtle changes in coordination geometries, and changes in the orientation of the coordinate vectors in the given ligands, as well as the dihedral angles between the two binding fragments (the chelate and the monodentate fragments) in the nonplanar ligands.

Tetrahedral Anion Cage: Self‐Assembly of a (PO4)4L4 Complex from a Tris(bisurea) Ligand

Theseanalogies provide promising ideas for the self-assembly ofnovel supramolecular systems based on anion coordination.In the past few decades, zero-dimensional, aestheticallypleasing metal coordination complexes, such as molecularsquares, capsules, tetrahedra, and other complex polyhedralshapes, have attracted much interest.

Stacking Interactions Induced Selective Conformation of Discrete Aromatic Arrays and Borromean Rings

Herein, we describe how to utilize stacking interactions to achieve selective supramolecular transformation and molecular Borromean rings (BRs). By using a dinuclear naphthalenediimide (NDI)-based Cp*Rh acceptor and linear bipyridyl ligands, organometallic rectangles featuring dynamic behavior have been constructed. Unique discrete aromatic stacking arrays were formed by inducing pyrene units as guest molecules. The topology of the BRs was realized by the use of a strategically chosen ligand which was capable of participating in D-A interactions and hydrogen bonding, as evidenced from single-crystal X-ray analysis and computational studies. These self-assembly processes underline the advantages of dynamic bonding and π-π stacking interactions, and serve to illustrate a new approach to generating structurally and topologically nontrivial supramolecular architectures.

Facile Separation of Regioisomeric Compounds by a Heteronuclear Organometallic Capsule

Owing to the often-similar physical and chemical properties of structural isomers of organic molecules, large efforts have been made to develop efficient strategies to isolate specific isomers. However, facile separation of regioisomeric compounds remains difficult. Here we demonstrate a universal organometallic capsule in which two silver centers are rigidly separated from each other by two tetranuclear [Rh4] pyramidal frustums, which selectively encapsulate a specific isomer from mixtures. Not only is the present heterometallic capsule suitable as a host for the encapsulation of a series of aromatic compounds, but also the receptor shows widely differing specificity for the various isomers. Direct experimental evidence is provided for the selective encapsulation of a series of para (p)-disubstituted benzene derivatives, such as p-xylene, p-dichlorobenzene, p-dibromobenzene, and p-diiodobenzene. The size and shape matching, as well as the Ag-π interactions, are the main forces governing the extent of molecular recognition. The encapsulated guest p-xylene can be released by using the solid-liquid solvent washing strategy, and the other guest molecules are easily liberated by using light stimulus.

Helical Supramolecular Assemblies of {2,4,6-[Cp∗Rh(E2-1,2-C2B10H10)(NC5H4CH2S)]3(triazine)} (E = S, Se) Shaped by Cp∗−Toluene−Cp∗ π-Stacking Forces and BH−Pyridine Hydrogen Bonding

Polycarborane-substituted molecules [Cp*Rh{E 2C 2(B 10H 10)}] 3(tpst) [E = S ( 2a), Se ( 2b)] were synthesized and characterized. 2a and 2b form toluene solvates in the solid state showing infinitely connected [( 2a, b)-(toluene)] infinity helices. The chains of these supramolecules are held together by Cp*-toluene-Cp* pi-stacking interactions of two of the three Cp* ligands of the bell-shaped 2a and 2b molecules. Unconventional BH (delta-)-pyridyl (delta+) aromatic hydrogen bonding enforces the bell-shapes of the molecular units, and the Cp* conformations are expected to induce the supramolecular structures.

Discrepant gas adsorption in isostructural heterometallic coordination polymers: strong dependence of metal identity

Two isostructural porous 3d–4d materials [M(cyclam)Pd(2,4-pydc)2·4H2O]n (2,4-H2pydc = pyridine-2,4-dicarboxylate acid) (1, M = Ni and 2, M = Zn) and five other isostructural complexes {[M′(cyclam)]2[M(2,5-pydc)3]·xH2O}n (2,5-H2pydc = pyridine-2,5-dicarboxylate acid) (3, M = Co, M′ = Ni; 4, M = M′ = Ni; 5, M = Zn, M′ = Ni; 6, M = Ni, M′ = Zn and 7, M = M′ = Zn) were synthesized. Both complexes 1′ and 2′ show high selective CO2 capture over CH4 and N2. The comparisons of different gas sorption properties between 1′ and 2′ strongly suggest that metal identity has a great influence on the polarity of frameworks, but just the polar molecules respond to the polarity changes of different frameworks. The comparisons of CO2 sorption properties between five other isostructural complexes 3′–7′ also strongly suggest that metal identity has great influence on polarity of frameworks and further the CO2 uptake.