Synthesis and crystal structures of rhodium acetate paddle‐wheel complexes with anchor group‐functionalised and hydrogen bond‐supported axial ligands

We report the synthesis and X-ray structures of four Rh2(OAc)4(LAx)2 (OAc=acetate, CH3COO−) paddle-wheel complexes (C1−C4) with methylthio-modified axial ligands LAx derived from benzamidine (L1), anilinopyrimidine (L2) or isothiourea (L3, L4) that are capable forming N−H⋅⋅⋅O hydrogen bonds to equatorially bridging acetate ligands. This was done aim suppress dissociation make amenable single-molecule conductance measurements in a scanning tunneling microscope break-junction (STM-BJ) setup. The characteristic spectroscopic features (NMR, IR, vis), crystal structures, hydrogen-bonding motifs DFT-based screening their frontier molecular orbitals presented. Our calculations suggest stabilises ligand binding by 15 kJ/mol 30 HOMO rhodium paddle-wheels is closer Au work function than LUMO, so expected constitute hole conductors.