Phospholyl (phosphacyclopentadienyl) and arsolyl (arsacyclopentadienyl) complexes of ytterbium(II) and samarium(II). Synthetic, structural and multinuclear (31P and 171Yb) NMR studies
摘要:
Bis(eta5-phospholyl) or bis(eta5-arsolyl)M(THF)2 complexes, where M = Sm or Yb, can be obtained either by reaction of potassium phospholides or arsolides with MI2(THF)2 or by cleavage of the P-P or As-As bond of a biphospholyl or biarsolyl by ytterbium or samarium metal powders. The THF molecules that coordinate to the metal are labile when the ligands are 2,3,4,5-tetramethylphospholyl or arsolyl, but not when they are 2,5-diphenylphospholyl. An X-ray crystal structure of bis(eta5-2,5-diphenylphospholyl)Yb (THF)2 is Presented. Yb-171 and P-31 NMR studies reveal that exchange of ligands is occurring in bis(eta5-2,3,4,5-tetramethylphospholyl)Yb(THF)2; this exchange is slow at room temperature and frozen at -20-degrees-C. For bis(eta5-2,5-phenyldiphenylphospholyl)Yb(THF)2 P-31 NMR data suggest that no exchange is occurring at room temperature.