Facile Formation of FePd Nanoparticles from Single-Source [1]Ferrocenophane Precursors

Mixed-metal FePd alloy nanoparticles
(NPs) have been synthesized
in moderate yield (ca. 55–60%) and at relatively low temperatures
from single-source [1]­ferrocenophane precursors. Thermolysis of [Fe­(η5-C5H4)2­Pd­(PnBu3)2] (7) (1 h, 150
°C) and the new species [Fe­(η5-C5H4)2­Pd­{PnBu2­(CH2)4­PnBu2}] (9) (1 h, 190 °C) afforded crystalline,
heterobimetallic FePd alloy NPs with diameters of ca. 4 nm (11) and 3.5 nm (12), respectively, together with
mixtures of unidentified, mainly ligand-derived products. Both sets
of particles were analyzed by high resolution transmission electron
microscopy, which, in addition to providing particle size, determined
the spacing between the lattice fringes to be 0.23 nm. Evidence for
the formation of alloy nanoparticles, rather than a mixture of those
comprising pure metals, was obtained by energy-dispersive X-ray analysis,
which confirmed the presence of both Fe and Pd in a single particle.
This assertation was further supported by wide-angle X-ray scattering
of 11 and 12, which displayed broad reflections
at 2θ = 40.58° and 40.09°, respectively, in good agreement
with previous studies of FePd NPs. Atomic absorption spectroscopy
was employed for bulk analysis of the particles and indicated that
that the compositions of 11 and 12 were
ca. Fe35Pd65.