REACTIONS OF YTTERBIUM(II) AMIDES WITH VARIOUS BRONSTED ACIDS, CS2 ORLINR(2) - CRYSTAL-STRUCTURES OF [(YB(NR(2))(MU-OCBU(3)(T)))(2)] AND [YB(OCBU(3)(T))(2)(THF)2] (R=SIME(3), THF=TETRAHYDROFURAN)

The reactions of [{Yb(NR(2))(mu-NR(2))}(2)] I or [Yb(NR(2))(2)(OEt(2)) (2)] II (R = SiMe(3)) with various Bronsted acids, carbon disulfide or LiNR(2) with N,N,N',N'-tetramethylethylenediamine (tmen) afforded the following complexes: (a) [{Yb(NR(2))(mu-OCBu(3)(t))}(2)] 1 from I and 2 Bu(3)(t)COH; (b) [{Yb(OCBu(3)(t))(mu-OCBu(3)(t))}(2)] 2 and [Yb(OCB u(3)(t))(2)(thf)(2)] 3 from I and 4 Bu(3)(t)COH in hexane or tetrahydr ofuran (thf), respectively; (c) [{Yb(OCBu(3)(t))(OR')}(x)] 4a (R' = C( 6)H(2)Bu(2)(t)-2,6-Me-4) from 1 and 2 HOR'; (d) [Yb(OCBu(3)(t))(OR')(t hf)(2)] 4b from 4a and an excess of thf; (e) [Yb(OCBu(3)(t))(OR')(py)( x)] 4c from 4b and an excess of pyridine (py); (f) Yb(O3SCF3)(2)(dme) 5 (dme = 1,2-dimethoxyethane) from II and 2 HO3SCF3; (g) [Yb(tmhd)(3)] 6 from I and 4 Htmhd (drop Bu(t)COCH(2)COBu(t)); (h) Yb(S(2)CNR(2))(2 ) 7 from II and 2 CS2; and (i) [Li{Yb(NR(2))(3)}(tmen)] 8 from II, LiN R(2) and tmen. A single-crystal X-ray diffraction study established 1 to be dimeric with asymmetrically bridging (-)OCBu(3)(t) ligands. In t his molecule the four-membered Yb2O2 ring has a fold angle of 24 degre es about the O(1)...O(2) direction, reducing the steric strain between adjacent bulky groups by bringing the two NR(2) groups slightly above the plane. Complex 3 is monomeric with the alkoxo and the tetrahydrof uran ligands in a distorted-tetrahedral configuration about the ytterb ium. One of the alkoxo ligands is bound in a conventional way with the Yb-O-C angle almost linear [175(2)degrees], while the other Yb-O-C an gle is significantly smaller [155(3)degrees].