Organostannoxane-Supported Multiferrocenyl Assemblies: Synthesis, Novel Supramolecular Structures, and Electrochemistry

Organotin metalloligands for selective sensing of metal ions

Four new organotin carboxylates, [(t-C₄H₉)₂Sn(L₁)₂] (1), [(t-C₄H₉)₂Sn(L₂)₂] (2), [{(n-C₄H₉)₂Sn(L₁)}₂O]₂ (3) and [{(n-C₄H₉)₂Sn(L₂)}₂O]₂ (4), are reported. All complexes selectively recognize Cu(ii) and Fe(iii) ions in solution. Complex 1 was found to be the best one for sensing those ions among all complexes.

Windmill-shaped octanuclear Zn/Ln (LnIII = Dy, Tb, Ho) heterometallic ensembles supported by a tetraferrocene scaffold

Utilizing a new ferrocene-based compartmental ligand, H₄L (1), a series of novel heterometallic complexes [{LZn(μ-OAc)Dy}₄(μ₄-H₂O)] (2), [{LZn(μ-OAc)Tb}₄(μ₄-H₂O)] (3), [{LZn(μ-OAc)Ho}₄(μ₄-H₂O)] (4), [L = Fe[(C₅H₄){-C(Me)[double bond, length as m-dash]N-N[double bond, length as m-dash]C₆H₃-(o-O)(m-O)}]₂] were synthesized and characterized. 2 and 3 crystallize in the monoclinic crystal system in the I2/m space group, whereas 4 crystallizes in the tetragonal crystal system in the I4/m space group. The tetra deprotonated ligand L^4- has two distinct coordination compartments: one pocket (2N, 2O) suitable for the transition metal (3d) ions and another pocket (4O) suitable for lanthanide (4f) metal ions. Additionally, the terminal phenoxo group can be utilized for cluster expansion. In all the complexes, the Zn^II ion is in a perfect square pyramidal (2N, 3O) geometry whereas the lanthanide ion has a coordination number of eight (8O) in a distorted biaugmented trigonal-prism geometry. The electrochemical properties of 2 and 3 along with ligand H₄L (1) were studied by cyclic voltammetry (CV). All the complexes display a similar type of electrochemical behavior viz., one quasi-reversible oxidation typical of a ferrocene/ferrocenium motif. The magnetic properties of all the complexes have also been investigated.

Phase-pure fabrication and shape evolution studies of SnS nanosheets

SnS nanosheets were synthesized by the injection of n-bis(piperidinedithiocarbamato)tin(iv) into oleylamine at 230 °C.

Cyclophosphazene–organostannoxane hybrid motifs in polymeric and molecular systems

The synthesis and structural characterization of two hybrid inorganic ring systems that contain interconnected cyclophosphazene–stannoxane motifs are reported.

Heterobimetallic metal-complex assemblies constructed from the flexible arm-like ligand 1,1'-bis[(3-pyridylamino)carbonyl]ferrocene: structural versatility in the solid state

The bidentate ferrocenyl sandwich molecule 1,1'-bis[(3-pyridylamino)carbonyl]ferrocene (3-BPFA) has been employed as an organometallic ligand in reactions with a series of transition metal salts to construct heterobimetallic architectures. X-ray crystallographic characterization reveals that the crystal packing of free ligand 3-BPFA induces spontaneous resolution of helical chains via intermolecular hydrogen bonds. By combining the flexibility from the arm-like molecule (3-BPFA) with the variation of the coordination property from different metal ions and/or the different counteranions, five different types of architectures are prepared: one octahedral coordination cage (copper(II) complex 1); two discrete pseudocapsules for combination of chlorine anions (nickel(II) complex 2 and cobalt(II) complex 3); two dimers with metal-metal interactions (silver(I) complexes 4 and 5); one macrocyclic complex (mercury(II) complex 6); and five two-dimensional mixed-metal-organic frameworks (M'-MOFs) (zinc(II), cadmium(II), and mercury(II) complexes 7-11). The structures of all complexes are characterized in detail by IR, elementary analysis, and single-crystal X-ray diffraction analysis. The factors inducing the structure variation among the complexes are discussed by taking account of the coordination geometry of different metal ions, the span angle between the two "arms", and the coordination mode of the 3-BPFA ligand.

Edge-to-face CH/pi aromatic interaction and molecular self-recognition in epi-cinchona-based bifunctional thiourea organocatalysis

The impact of cooperativity between intermolecular interactions is demonstrated by the molecular self-recognition properties of highly enantioselective epi-cinchona bifunctional thiourea organocatalysts. Low-temperature NMR experiments in inert solvents have revealed two sets of nonequivalent resonances in equal population for thiourea-modified members of the epi-quinine and epi-quinidine families. In solution, the predominance of an asymmetric (C1) dimeric self-assembly with noteworthy structural motifs became evident: simultaneous intra- and intermolecular thiourea hydrogen bonding and a CH/pi interaction were observed. Both the stereochemical and the diverse conformational features of the system favor the observed quinoline T-shaped aromatic pi-pi stacking interaction. The structure findings are supported by quantitative proton-proton distance data that were available from NOE buildup curves. The 3D structure of the dimeric assembly has been modeled in agreement with the H-H distance restraints. Owing to the geometrical preference associated with the dimerization process, the self-assembled bifunctional system is interpreted as a charge-transfer complex with the potential for catalyst self-activation.

Nanodimensional organostannoxane molecular assemblies

Organooxotin cages, clusters, and coordination polymers containing [Sn 2(mu-O)], [Sn 2(mu-OH)], [Sn 2(mu-O) 2], [Sn 2(mu-OH) 2], and [Sn 3(mu 3-O)(mu-OR) 3] building blocks have been assembled by the reactions of organotin precursors with phosphonic, phosphinic, carboxylic, or sulfonic acids. Various synthetic methodologies including Sn-C bond cleavage reactions and solventless procedures have been utilized to generate several nanodimensional organostannoxane assemblies. The synthesis, structure, and structural interrelationship of these diverse organostannoxane compounds are discussed. The synthetic knowledge gained to prepare specific organostannoxane structural forms in high yields has been utilized for the construction of dendrimer-like molecules. These contain a central stannoxane core and a functional periphery. The functional periphery can be readily modulated to assemble photoactive, electroactive, or multisite coordinating molecules. The synthesis, structure, and potential uses of these compounds are discussed.