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

Selenosalicylic acid ( ortho -HSeC 6 H 4 CO 2 H), the heavy element congener of the widely studied thiosalicylic acid, was prepared by reaction of 2-carboxybenzenediazonium chloride (HO 2 CC 6 H 4 N 2 + Cl - ) with Na 2 Se 2 , followed by reduction of the resulting diselenide (SeC 6 H 4 CO 2 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(SeC 6 H 4 CO 2 )(PPh 3 ) 2 ], [{( p -cym)Ru(SeC 6 H 4 CO 2 )} 2 ] ( p -cym = η 6 - p -cymene, CH 3 C 6 H 4 CH(CH 3 ) 2 ), [{Cp*Rh(SeC 6 H 4 CO 2 )} 2 ] (Cp* = η 5 -C 5 Me 5 ) and [Cp*Ir(SeC 6 H 4 CO 2 )(PPh 3 )], 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(SeC 6 H 4 CO 2 )} 2 ] and [Cp*Ir(SeC 6 H 4 CO 2 )(PPh 3 )].