SYNTHESIS AND STRUCTURAL CHARACTERIZATIONS OF (MU(3)-H(PH)C=C)FECO2(CO)(7)DPPFE (DPPFE = 1,1'-BIS(DIPHENYLPHOSPHINO)FERROCENE) - INTRAMOLECULAR PI-PI INTERACTION BETWEEN THE APICAL PHENYL GROUP OF THE CLUSTER AND A PHENYL GROUP IN DPPFE

Thermal reaction of {mu(3)-H(Ph)C=C) FeCo2(CO)(9) (1) with dppfe in be nzene affords dark green {mu(3)-H(Ph)C=C} FeCo2(CO)(7)dppfe (2). The m olecular structures of 1 and 2 have been determined by single crystal x-ray analysis; dppfe replaces two equatorial carbonyls from two Co(CO )(3) groups. Thus, dppfe approaches the apical phenyl group. This unus ual conformation has been analyzed by computer visualization of the pi electrons of the apical phenyl group and one of the phenyl groups in dppfe to indicate an intramolecular pi-pi interaction between these tw o phenyl groups. Atomic charge analysis by Extended Huckel (E.H.) calc ulation suggests why dppfe coordinates to Co atoms preferentially Cycl ic voltammetric behavior for these compounds is interpreted in terms o f HOMO and LUMO, which have also been analyzed by E.H. calculations.