Nitrogen ligands, transition metal characterization

L. K. Gupta and S. Chandra, Physicochemical and biological characterization of transition metal complexes with a nitrogen donor tetra-dentate novel macro-cyclic ligand, Transition Metal Chemistry, vol. 31, no. 3, pp. 368-373, 2006. 

Herein we have reported the synthesis, characterization, and reactivity of both transition metal and actinide elements supported by tripodal ligand scaffolds. The carbon-anchored ligands TIME normally form polynuclear species while the nitrogen-anchored ligands TIMEN can coordinate to transition metals in a 1 1, fashion, rendering the coordinated metal centers in well-protected pockets. 

The preparation of tropidinyl transition metal complex 53 was achieved by reaction of 4-trimethylstannyltropidine 52 with M(CO)sBr, M = Mn, Re <2003ZFAC2408>. In complex 53, the tropidinyl ligand is coordinated through the nitrogen and the three-carbon allylic system which serve as a 2o /47t-electron donor. It has been characterized by single-crystal X-ray diffraction analysis (Equation II). 

Transition metal atoms coordinated by dithiocarbamate ligands through four sulfur atoms have both electronic (free d-orbitals) and steric (free octahedral sites) propensity to form adducts with nitrogen bases, since nitrogen atoms have one sp -hybrid orbital, which is occupied by the lone pair of stereochem-ically active electrons. To characterize newly prepared adducts of dimethyl-, diethyl- and morpholinedithiocarbamate zinc(II) complexes with cyclic N-donor bases, such as pyridine, piperidine, hexamethyleneimine and morpholine, compounds 28-35 have been prepared and studied by and CP/MAS... 

---