PHOSPHINOMETHANIDE COMPLEXES OF LANTHANOI DS

By reaction of LnI(2).2THF, Ln = Yb, Sm with the phosphinomethanides L i[C(PMe(2))(2)X], X = SiMe(3), PMe(2) the addition products {(THF)Ln[C (PMe(2))(2)X]2I2Li(THF)}, Ln = Yb, X = SiMe(3) (1a), X = PMe(2) (1b) a nd Ln = Sm, X = SiMe(3) (2) are obtained; la could be characterized by X-ray crystal structure analysis. In contrast, complete substitution is achieved in the reaction of lanthanide triflates with lithium phosp hinomethanides. Thus the seven-coordinated and X-ray structurally char acterized complex {(THF)Lu[C(PMe(2))(2)(SiMe(3))](3)} (3) is obtained. Lu[C(PMe(2))(2)(SiMe(3))](3) (4) could be obtained from 3 by removing thf in vacuo or by reaction of Lu(CF3SO3)(3) with Li[C(PMe(2))(2)(SiM e(3))] in toluene. The derivative {(THF)Lu(Me)[C(PMe(2))(2)(SiMe(3))]( 2)} (5) has been isolated by treatment of 3 with LiMe. In a somewhat r andom way, one run with LiMe gave the X-ray structurally characterized , anionic complex THF)(4)Li]{Lu(OSiMe(3))[C(PMe(2))(2)(SiMe(3))](3)} ( 6) obviously by cleavage of silicon grease. A coordination number of e ight is observed in the anionic complexes {Ln[C(PMe(2))(2)(SiMe(3))]Li -4}, Ln = Er (7), Y (8) und La (9). The X-ray crystal structure of 9 v erifies the new type of an eightfold phosphorus coordinated lanthanoid center. In compounds Sc[C(PMe(2))(2)X)](3), X = SiMe(3) (10a) and X = PMe(2) (10b) the phosphino-methanide ligands are arranged in an inter mediate coordination mode between a-chelating and ii-type coordination as revealed by X-ray diffraction. The X-ray structurally characterize d dimeric complex {Sm[CH(PMe(2))(2)](3)}(2) (11) combines two differen t phosphinomethanide coordination modes. Two phosphinomethanide ligand s in 11 adopt a pi-type coordination, the third ligand is arranged in a eta(2), mu-C,P fashion.