SYNTHESIS, STRUCTURE AND REACTIVITY OF FERROPHOSPHONIUM SALTS [CPFE(CO)(L)(PPH2CHR')]BF4 (L=CO, CH3CN, P(N)BU3, R'=PH,CN, COOET, PPH2, SIME3) - CRYSTAL-STRUCTURE OF [CPFE(CO2PPH2CH2SIME3]BF4 AND [CPFE(PPH2CH2PH)CPFE(CO)](MU-CO)2

Stoichiometric addition of the phosphine PPh2CH2R' to the aquo complex [CpFe(CO)2(H2O)]BF4, which is obtained from the dimer [CpFe(CO)2]2, gives functionalized alkylphosphine ligand complexes of the type [CpFe(CO)2PPh2CH2R']BF4 (R' = Ph, CN, SiMe3, COOEt, PPh2) (1a-e) in high yields. The tri-n-butylphosphine complex [CpFe(CO)2(PnBu3)]BF4 (1f) is prepared analogously. The neutral, dimeric monophosphine complex [CpFe(PPh2CH2Ph)CpFe(CO)](mu-CO)2 (3) is formed by the reaction of 1a with OH-. Direct substitution of CO in 1a-f by a second phosphine ligand does not give pure products except for 1f, which gives 4 in the presence of OH- and in contrast to the base reaction. However, alkylphosphine ligands which are activated in the alpha-position can be used to prepare [CpFe(CO)(pnBu3)(PPh2CH2CN)]BF4 (6) quantitatively, by thermal substitution of CH3CN in [CpFe(CO)(CH3CN)(PnBu3)]BF4 (5) obtained from 1f and acetonitrile. The ease of substitution of the new complexes, and their structures are discussed in terms of IR, H-1 and P-31 NMR data, along with cone angle comparison of the phosphines. The X-ray molecular structures of the ionic complex 1c and thc neutral dimer 3 are determined and discussed.