Synthesis and properties of nickel(I) and Nickel(II) complexes of a series of macrocyclic N{sub 4} ligands: Crystal structures of C-RSSR-[Ni{sup I}HTIM](ClO{sub 4}), C-RSSR-[Ni{sup II}HTIM](ClO{sub 4}){sub 2}, C-RRSS-[Ni{sup II}HTIM](ClO{sub 4}){sub 2}, and [Ni{sup II}TIM](ClO{sub 4}){sub 2} (HTIM = 2,3,9,10-tetramethyl-1,4,8,11-tetraazacyclotetradecane, TIM = 2,3,9,10-tetramethyl-1,4,8,11-tetraazacyclotetradeca-1,3,8,10-tetraene)
- Brookhaven National Lab., Upton, NY (United States)
Two isomers of the square-planar nickel(II) complex of 2,3,9,10-tetramethyl-1,4,8,11-tetraazacyclotetradecane (HTIM) were prepared from the nickel (II) complex of 2,3,9,10-tetramethyl-1,4,8,11-tetraazacyclotetradeca-1,3,8-10-tetraene (TIM) by NaBH{sub 4} reduction in aqueous solution. The properties of Ni(II) complexes, Ni(I) complexes, and Ni(I)-CO complexes with a series of 14-membered macrocyclic N{sub 4} ligands were studied by means of UV-vis, NMR, and IR spectroscopy. The CO binding constants range from 1.3 x 10{sup 2} to 2.8 x 10{sup 5} M{sup -1} at 25 {degrees}C in acetonitrile. The crystal structures of C-RSSR-[Ni{sup I}HTIM]ClO{sub 4} (1), C-RSSR-[Ni{sup II}HTIM](ClO{sub 4}){sub 2} (2), C-RRSS-[Ni{sup II}HTIM](ClO{sub 4}){sub 2} (3) and [Ni{sup II}TIM](ClO{sub 4}){sub 2} (4) have been determined from single-crystal X-ray diffraction data collected by using Mo K{alpha} radiation. All complexes have square-planar geometry and the stereochemistry of the four coordinating N atoms in complexes (1), (2), and (3) is Trans III. Although the two sets of Ni-N distances of 2.083(3) and 2.053(3) {angstrom} for the Ni(I) complex, (1), are much longer than those of 1.969(1) and 1.969(1) and 1.948(2) {angstrom} for the corresponding Ni(II) complex, (2), distortion of the macrocycle core was not observed upon the reduction of the metal center. The structural changes associated with the reduction of Ni(II) to Ni(I) in square-planar complexes can be classified in three ways: (1) expansion of Ni-N distances; (2) distortion of nickel core; (3) both expansion and distortion.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 421016
- Journal Information:
- Inorganic Chemistry, Vol. 33, Issue 25; Other Information: PBD: 7 Dec 1994
- Country of Publication:
- United States
- Language:
- English
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