TRIPOD LIGANDS OF CONSTITUTIONAL C-1 SYMMETRY CONTAINING A DELIBERATESET OF MIXED P S DONOR GROUPS - SYNTHESIS AND COORDINATION CHEMISTRY/

Various efficient strategies for the preparation of tripod ligands wit h mixed P/S donor sets such as H3CC(CH2PPh2)(CH2SR)(CH2SR') (6) or thr ee different S donors H3CC(CH3SR)(CH3SR')(CH2SR'') (5) are described. Compounds 5 are capable of acting as tridentate chelate ligands in com plexes such as [H3CC(CH2SEt)((CH2SPr)-Pr-i)(CH2S'Bu)Mo(CO)(3)] (9b). Q uite alike compounds 6 act as tripod ligands as evidenced by the isola tion and structural characterization of three derivatives [H3CC(CH2PPh 2)(CH2SR)(CH2SR')Mo(CO)(3)] (11a, 11c, 11e). It is shown that under 1 bar CO substitution of one SR group by CO occurs to give [H3CC(CH2PPh2 )(CH2SR)(CH2SR')Mo(CO)(4)] (12). With 11a, [H3CC(CH2PPh2)(CH2SPh)(CH2S Bn)Mo(CO)(3)], as the starting compound the carbonylation gives exclus ively 12a with the CH2SPh group playing the role of the dangling arm. All the new compounds are fully characterized by NMR and mass spectrom etric techniques as well as by IR spectra and cyclovoltammetric data a nd X-ray analysis for the coordination compounds. (C) 1998 Elsevier Sc ience S.A.