Ligand Isomerism in Coordination Cages.

Complexation reactions of palladium(II) nitrate with a set of 3-pyridyl appended nonchelating bidentate ligands possessing regioisomeric phenylene-diurea functionalities as spacers were carried out. The ligands utilized in this study are 1,1'-(1,2-phenylene)bis(3-(pyridin-3-yl)urea), L1; 1,1'-(1,3-phenylene)bis(3-(pyridin-3-yl)urea), L2; and 1,1'-(1,4-phenylene)bis(3-(pyridin-3-yl)urea), L3. The complexation reactions of the ligands (L1, L2, and L3) with palladium(II) produced single discrete isomeric cages (1, 2, and 3) of PdL formulation in each case and thereby illustrated ligand-isomerism in coordination cages.

Crystal structure of bis-(2-amino-anilinium) hydrogen phosphate.

The asymmetric unit of the title compound, 2C6H9N2 (+)·HPO4 (2-), comprises two 2-amino-anilinium cations and one hydrogen phosphate dianion. In the crystal, the HPO4 (2-) dianions are linked by O-H⋯O hydrogen bonds into chains along [100]. The inorganic anionic chains and organic cations are linked by N-H⋯O and N-H⋯N hydrogen bonds, forming a two-dimensional supra-molecular network extending parallel to (001).

Hypoelectronic 8-11-Vertex Irida- and Rhodaboranes.

A series of novel isocloso-diiridaboranes [(Cp*Ir)2B6H6], 1, 2; [1,7-(Cp*Ir)2B8H8], 4; [1,4-(Cp*Ir)2B8H8], 5; [(Cp*Ir)2B9H9], 8; isonido-[(Cp*Ir)2B7H7], 3; and 10-vertex cluster [5,7-(Cp*Ir)2B8H12], 6 (Cp* = η(5)-C5Me5) have been isolated and structurally characterized from the pyrolysis of [Cp*IrCl2]2 and BH3·thf. On the other hand, the corresponding rhodium system afforded 10- and 11-vertices clusters [5-(Cp*Rh)B9H13)], 7, and [(Cp*Rh)2B9H9], 9, respectively. Clusters 1 and 2 are topological isomers.

Gallium and indium complexes containing the bis(imino)phenoxide ligand: synthesis, structural characterization and polymerization studies.

A series of gallium and indium complexes containing a bis(imino)phenolate ligand framework were synthesized and completely characterized with different spectroscopic techniques. The molecular structures of a few complexes were determined using single crystal X-ray diffraction studies. These compounds were found to be extremely active towards the bulk ring opening polymerization (ROP) of lactides yielding polymers with high number average molecular weight (Mn) and controlled molecular weight distributions (MWDs).

Octadecanuclear gear wheels by self-assembly of self-assembled "double saddle"-type coordination entities: molecular "rangoli".

A series of self-assembled "double saddle"-type trinuclear complexes of [Pd3L'3L2] formulation have been synthesized by complexation of a series of cis-protected palladium(II) components with a slightly divergent "E-shaped" non-chelating tridentate ligand, 1,1'-(pyridine-3,5-diyl)bis(3-(pyridin-3-yl)urea (L). The cis-protecting agents L' employed in the study are ethylenediamine (en), tetramethylethylenediamine (tmeda), 2,2'-bipyridine (bpy), and 1,10-phenanthroline (phen), for 1, 2, 3, and 4, respectively. The crystal structures of [Pd3(tmeda)3(L)2](NO3)6 (2), [Pd3(bpy)3(L)2](NO3)6 (3), and [Pd3(phen)3(L)2](NO3)6 (4) unequivocally support the new architecture.