| Abstrakt: |
Dichlorides of group 12 elements react with (NEt4)[HFe(CO)4] in tetrahydrofuran to give the di-hydrides [(OC)4HFe-E-FeH(CO)4] (E = Zn, Cd, Hg) in good yields. These compounds undergo proton abstraction by nBuLi to give di-anions [(OC)4Fe-E-Fe(CO)4]2-, stabilized as their bis(triphenylphosphine)nitrogen(+) (PPN+) salts. (PPN)2[(OC)4Fe-Hg-Fe(CO)4] crystallizes in the triclinic system, space group P1with a20.382(3), b15.328(2), and c13.420(2) Å; α 115.96(3), β 108.89(2), and γ 87.09(2)o, and Z= 2. The anion consists of an almost linear spine (Fe-Hg-Fe angle 178.7(1)o), with an average Fe-Hg bond distance of 2.546(2) Å. The Fe atoms display a trigonal bipyramidal geometry, and the equatorial CO groups linked to the iron atoms are in an eclipsed conformation, resulting in an idealized D3hsymmetry. The existence of two conformers for this anion and the presence of Hg · · · CO backbonding are discussed on the basis of qualitative molecular orbital theory. The [(OC)4Fe-Hg-Fe(CO)4]2-anion undergoes redistribution reactions with [M(CO)3(η-C5H5)]2Hg (M = Mo, W) to give the new unsymmetrical anions [(OC)4Fe-Hg-M(CO)3(η-C5H5)]-. |
