Michael C. B. Colbert, Jack Lewis, Nicholas J. Long, Paul R. Raithby, Andrew J. P. White and David J. Williams
A series of novel heterobimetallic bis(acetylide) ferrocene complexes
featuring a bis[1,2-bis(diphenylphosphino)methane]ruthenium centre and
seven variously substituted aromatic acetylene ligands have been
synthesised and characterised. The crystal structure of
trans-[Ru(dppm)2{CC(C5H4
)Fe(C5H5
)}2
]
shows the ruthenium centre in a distorted-octahedral environment bound to
two ferrocene units in a linear fashion by ‘rigid-rod’-like
acetylene linkages. The conformation is stabilised by strong intramolecular
CH·
·
·π(C
C) interactions.
Electrochemical studies showed that incorporation of donor-substituted
aromatic acetylide ligands causes a cathodic shift in the
RuII/III redox potential. Conversely, an anodic shift is
observed when electron-withdrawing substituents are present in the
acetylide systems. Electronic spectral measurements indicated that the
systems belong to the Robin and Day ‘Class II’ mixed-valence
species and suggest that greater electronic interaction occurs in the
bis(acetylide) complexes than in the corresponding monoacetylide
chloro-complex.