 Most common organoactinide complexes involve π bonding with ligands such as cyclopentadienyl, but there are a few exceptions, namely in thorium and uranium chemistry as these are the most easily handleable elements of this group.Attempts to synthesize uranium alkyls were first made during the Manhattan project by Henry Gilman, inspired by the volatility of main group organometallics.However he noticed that these compounds tend to be highly unstable.