Synthesis and characterization of thienyl phosphines and thienyl phosphine chalcogenides

Abstract

Functionalized phosphine and phosphine chalcogenide ligands have the potential for applications in organometallic, inorganic and polymer chemistry. They serve as traditionally versatile donor ligands but also as handles for further chemical modification. The synthesis of 2-diisopropylphosphinothiophene (1), 2-bromo-5-diisopropylphosphinothiophene (2) and 5-diisopropylphosphino-2,2′-bithiophene (3) were performed. Compounds 1, 2 and 3 were isolated via lithium halogen exchange of 2-bromothiophene, 2,5-dibromothiophene, or 2,2′-bithiophene followed by addition of chlorodiisopropylphosphine, respectively. Compounds 1, 2, and 3 were then converted to the phosphine chalcogenides by reaction with elemental sulfur or selenium in toluene to yield 2-diisopropylphosphinothiophene sulfide (4), 2-diisopropylphosphinothiophene selenide (5), 2-bromo-5-diisopropylphosphinothiophene sulfide (6), 2-bromo-5-diisopropylphosphinothiophene selenide (7), 5-diisopropylphosphino-2,2′-bithiophene sulfide (8) and 5-diisopropylphosphino-2,2′-bithiophene selenide (9). All compounds 1–9 were isolated in excellent yields (85%-quantitative). 1H, 13C, and 31P NMR, elemental analysis and gas chromatography mass spectrometry, were used to characterize the new phosphines and phosphine chalcogenides.