Selenosalicylate; a little-studied heavy-element analogue of the versatile thiosalicylate ligand.

Selenosalicylic acid ( ortho -HSeC6 H4 CO2 H), the heavy element congener of the widely studied thiosalicylic acid, was prepared by reaction of 2-carboxybenzenediazonium chloride (HO2 CC6 H4 N2 + Cl- ) with Na2 Se2 , followed by reduction of the resulting diselenide (SeC6 H4 CO2 H)2 with zinc and acetic acid. The coordination chemistry of the selenosalicylate ligand towards a variety of platinum(ii), palladium(ii), nickel(ii), gold(iii), gold(i), rhodium(iii), iridium(iii) and ruthenium(ii) centres was explored. X-ray crystal structure determinations were carried out on the complexes [Pt(SeC6 H4 CO2 )(PPh3 )2 ], [{( p -cym)Ru(SeC6 H4 CO2 )}2 ] ( p -cym = η6 - p -cymene, CH3 C6 H4 CH(CH3 )2 ), [{Cp*Rh(SeC6 H4 CO2 )}2 ] (Cp* = η5 -C5 Me5 ) and [Cp*Ir(SeC6 H4 CO2 )(PPh3 )], and comparisons are made with corresponding thiosalicylate complexes. The complexes were characterised by NMR spectroscopy as well as ESI mass spectrometry, which indicated a greater propensity for fragmentation including by selenium loss, compared to the thiosalicylate analogues. Hirshfeld surface analysis to visualise and quantify intermolecular interactions revealed the dominance of H⋯H contacts in [{( p -cym)Ru(SeC6 H4 CO2 )}2 ] and [Cp*Ir(SeC6 H4 CO2 )(PPh3 )].