Related Experiment Video
Updated: Jun 16, 2026

Amide Coupling Reaction for the Synthesis of Bispyridine-based Ligands and Their Complexation to Platinum as Dinuclear Anticancer Agents
Published on: May 28, 2014
Steric control of coordination geometry in titanium-imido complexes of N,N'-bis(arylimino)acenaphthylene ligands
Kensha Marie Clark1, Joseph W Ziller, Alan F Heyduk
1Department of Chemistry, University of California, Irvine, California 92697, USA.
Abstract:
Titanium complexes of N,N'-bis(arylimino)acenaphthylene (BIAN) alpha-diimine ligands with varied steric profiles have been prepared. Coordination of the BIAN ligand derivatives to TiCl(4) afforded the adducts (dpp-BIAN)TiCl(4) (1a), (tmp-BIAN)TiCl(4) (1b), and (dmp-BIAN)TiCl(4) (1c) (dpp = 2,6-diisopropylphenyl; tmp = 2,4,6-trimethylphenyl; dmp = 3,5-dimethylphenyl). While the least sterically crowded complex 1c is robust toward loss of the diimine ligand, the dpp-BIAN and tmp-BIAN ligands are readily displaced by pyridine from the more crowded derivatives 1a and 1b, respectively. The crowded profiles engendered by the tmp-BIAN and dpp-BIAN ligands result in the formation of five-coordinate titanium-imide complexes, (dpp-BIAN)TiCl(2)(=N(t)Bu) (2a) and (tmp-BIAN)TiCl(2)(=N(t)Bu) (2b), upon addition of (t)BuNH(2) to solutions of 1a or 1b, respectively. Single-crystal X-ray diffraction studies reveal a square pyramidal coordination environment with an apical imide ligand and a short Ti-N distance, consistent with a Ti-N triple bond. Conversely, the less crowded dmp-BIAN ligand affords a six-coordinate titanium imido complex, (dmp-BIAN)TiCl(2)(=N(t)Bu)(NH(2)(t)Bu) (4), upon treatment of 1c with (t)BuNH(2). Surprisingly the imido ligand is coordinated trans to one arm of the diimine. This six coordinate species is fluxional in solution, and exchange and variable temperature (1)H NMR experiments suggest dissociation of the coordinated (t)BuNH(2) ligand to generate a five-coordinate imido intermediate analogous to 2a and 2b.
More Related Videos
10:52Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
Published on: July 27, 2022
09:37Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry
Published on: October 18, 2019
Related Concept Videos
Coordination Number and Geometry
Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Stereoisomerism
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Metal-Ligand Bonds
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
Valence Bond Theory
Coordination Compounds and Nomenclature