57Fe NMR spectroscopy of ferrocenes derived from aminoferrocene and 1,1'-diaminoferrocene.
Three series of ferrocenes, derived from aminoferrocene Fc-NH2 and 1,1'-diaminoferrocene fc(NH2)2, were studied by 57Fe NMR spectroscopy. A marked decrease in 57Fe magnetic nuclear shielding with respect to ferrocene is observed if the nitrogen atom becomes part of a pi-acceptor linked to one or both cyclopentadienyl rings. In contrast, pi-donor properties of the amino group(s) affect delta57Fe to a much smaller extent. In the case of the fairly rigid structures of 1,3-diaza-2-element-[3]ferrocenophanes, a significant increase of 57Fe nuclear magnetic shielding is observed, in contrast to the corresponding [n]ferrocenophanes with n > 3. Structures of numerous of the ferrocene derivatives have been optimized for the gas phase by calculations (B3LYP/6-311 + G(d,p) level of theory), and 57Fe nuclear magnetic shieldings were calculated using these geometries. There is reasonable agreement in the trends for experimental and calculated data.
Anorganische Chemie II, Universität Bayreuth, D-95440 Bayreuth, Germany. b.wrack@uni-bayreuth.de
Bernd
B
Wrackmeyer
Elena V
EV
Klimkina
Heidi E
HE
Maisel
Oleg L
OL
Tok
Max
M
Herberhold
D005296:Ferrous Compounds / Q000737:chemistry*; D005740:Gases; D007503:Iron Isotopes; D009682:Magnetic Resonance Spectroscopy; D000075163:Metallocenes; D015394:Molecular Structure
D005296:Ferrous Compounds; D005740:Gases; D007503:Iron Isotopes; D000075163:Metallocenes; C004998:ferrocene