Syntheses of very soluble alkylated bicyclic guanidinate ligands and structural characterization of a dipalladium paddlewheel

Fool-proof syntheses of two highly soluble tetraalkylated bicyclic guanidinates which are characterized by the NC(N)N core are reported along with the structures of the corresponding hydrochlorides. The compound with alkyl = methyl was used to prepare a paddlewheel species with a Pd24+ core devoid of a strong metal–metal bond but potentially useful as precursor to a rare single bonded Pd26+ species. The Pd1⋯Pd2 separation is only 2.5488(12) Å and the local coordination for each of the d8 Pd(II) atoms is square planar.

Two very soluble alkylated bicyclic guanidinates having a NC(N)N core have been synthesized and fully characterized. These compounds serve as ligand precursors to soluble metal-containing complexes as shown by a paddlewheel complex that has a Pd24+ core.Figure optionsDownload as PowerPoint slideHighlights
► A fool-proof preparation of two very soluble alkylated bicyclic guanidinates is provided.
► It is shown that these compounds can give rise to highly soluble paddlewheel compounds.
► A dipalladium complex with a Pd24+ core has been structurally characterized.
► The paddlewheel complex with a Pd24+ may serve as precursor to metal–metal bonded compounds with Pd26+ cores having a bond order of one.