“…The iron atoms exist in the oxidation states 0, + 2 and + 3, from which + 3 by far prevails. The inner coordination sphere about iron atoms are Fe (0) (Achak et al , 1996 ), Hg (Sosinski et al , 1983 ), FeC 10 (Mammano et al , 1977 ;Graziani et al , 1980 ;Yukle et al , 1996 ), FeC 3 HBr 2 (Enland et al , 1997 )]; Fe(II): [FeN 3 ( H ö hn et al, 1991 ), FeS 4 (Achak et al , 1996 ;Bowers et al , 1996 ;Akari et al , 1998 ), FeC 6 (Adam et al , 1990 ;Behrens et al , 1991 ;Schwarz et al , 1996 ;Yian et al , 1996 ), FeN 5 O and FeN 4 O 2 (Cingi et al , 1985 )]; Fe(III): [FeC 5 N (Castellano et al, 1977, Kl ü fers andHauss ü l, 1985 ;Mulliza et al , 1990 ;Navaza et al , 1990 ;Johnson et al , 1991 ), FeC 6 (Mayer and Pichard , 1988 ;Meyer and Pickerdt , 1989 ;Swartner et al , 1997 ), FeO 4 N 2 (Pavel č í k and Kettmann, 1983 ), FeO 6 (Burger and Kl ü fers, 1966a,b ;Calogero et al , 1977 ), FeO 5 N 2 (Cohen and Hoard , 1966 ;Solans et al , 1984a,b ), and FeO 4 N 3 (Chuklianova et al , 1981 )]. The mean Fe(0)-L bond distance elongated in the order: 1.69 ( μ -H) < 1.78 ( μ -CO) < 2.045 (C, cp) < 2.317 (Zn) < 2.522 (Hg) < 2.627 (In) < 2.641 (Bi).…”