Original scientific paper

Structure and Relative Stability of Dirhodium Tetracamphanate Adducts with 5-Pyrido- 1,4-benzodiazepines and Their 4,5-Dihydro Congeners; First Representatives of Non-Symmetric Bidentate 1,4-Bisnitrogen Ligands

Zlata Raza ; Ruđer Bošković Institute, P.O.B. 1016, 10000 Zagreb, Croatia
Branimir Klaić ; Ruđer Bošković Institute, P.O.B. 1016, 10000 Zagreb, Croatia
Radovan Marčec ; Ruđer Bošković Institute, P.O.B. 1016, 10000 Zagreb, Croatia
Vladimir Vinković ; Ruđer Bošković Institute, P.O.B. 1016, 10000 Zagreb, Croatia
Vitomir Šunjić ; Ruđer Bošković Institute, P.O.B. 1016, 10000 Zagreb, Croatia

Abstract

1H-NMR Spectra of dirhodium tetracamphanate adducts with 5- pyrido-1,4-benzodiazepin-2-ones 3-5 reveal different modes of com- plexation. Depending on the structure of the chelating pyridoben- zodiazepine, two types of kinetic and dynamic profiles are observed. Ligands 3 and 4, possessing a 1,4-bisnitrogen subunit with 47t electrons, behave as bidentate ligands and form the kinetically stable 1:1 adducts, non-symmetric diastereomers 6A, 7A, which undergo fast isomerization into the thermodynamically more stable 6B, 7B. Ligand 5 (4,5-dihydro derivative of 4) behaves as a pyridine derivative, forming the kinetically stable, symmetric 2:1 aduct 8, which very slowly isomer- izes into non-symetric 1:1 aduct 9. The relative stability of 8 is attributed to the hydrogen bonding N(4)-H-0(camphanyl), as well as to the low coordinating ability of the non-conjugated, pyramidal N(4) atom.

Keywords

Hrčak ID:

135957

URI

https://hrcak.srce.hr/135957

Publication date:

4.3.1996.

Visits: 1.104 *