Ring openings of lactone and ring contractions of lactide by frustrated Lewis pairs.

While B(C(6)F(5))(3) forms the adducts (CH(2))(4)CO(2)B(C(6)F(5))(3)1 and (CHMeCO(2))(2)B(C(6)F(5))(3)7 with δ-valerolactone and lactide, the frustrated Lewis pairs derived from B(C(6)F(5))(3) and phosphine or N-bases react with lactone to effect ring opening affording zwitterionic species of the form L(CH(2))(4)CO(2)B(C(6)F(5))(3) (L = tBu(3)P 2, Cy(3)P 3, C(5)H(3)Me(3)N 4, PhNMe(2) 5, C(5)H(6)Me(4)NH 6) while reaction with rac-lactide results in ring contraction to give salts [LH][OCCHMeCO(2)(CMe)OB(C(6)F(5))(3)] (L = tBu(3)P 8, Cy(3)P 9, C(5)H(3)Me(2)N 10, C(5)H(6)Me(4)NH 11). The mechanistic implications of these reactions are discussed.

Reactions of Zn bis-ferrocenyl-β-diketiminates with [Ph3C][B(C6F5)4].

The ZnMe complexes of bis-ferrocenyl-β-diketiminate ligands are prepared and the reactions with [Ph(3)C][B(C(6)F(5))(4)] are found to yield the salts [H(Ph(3)C)C(MeC(N(C(5)H(4))FeCp)(2)ZnMe] [B(C(6)F(5))(4)] and [CH(2)=C(MeC(N(C(5)H(4))FeCp)(2)ZnMe][B(C(6)F(5))(4)], derived from electrophilic substitution and hydride abstraction.

Ti and Zr complexes of ferrocenyl amidinates.

Preparation of a N-ferrocenyl-amidinate complex was achieved by employing (TMEDA)Li[(CpFeC(5)H(4))NC(Ph)NSiMe(3)] (1) to prepare Cp*Zr[(CpFeC(5)H(4))NC(Ph)NSiMe(3)]Cl(2) (2). Complex 2 exhibited poor polymerization activity and thus a series of C-ferrocenyl bis(amidinate) complexes of the type M(L)(2)Cl(2) (M = Zr, 4; M = Ti, 5; L = (CyNC(CpFeC(5)H(4))NCy) were synthesized via reaction of ferrocenyl-amidine, H(L) and M(NMe(2))(2)Cl(2) (M = Ti, Zr·2THF). Half sandwich mono(amidinate) complexes, Cp'ZrLCl(2) (Cp' = Cp, 7; Cp' = Cp*, 8), were prepared by the reaction of Cp'ZrCl(3) with Li(L) and subsequently alkylated to give M(L)(2)Me(2) (M = Zr, 9; M = Ti, 11), CpZr(L)(CH(2)Ph)(2) (12) and Cp*Zr(L)Me(2) (10) with the appropriate alkylating agent.

Rare-earth amidate complexes. Easily accessed initiators for epsilon-caprolactone ring-opening polymerization.

The direct synthesis of yttrium amidate complexes using the simple reaction of amide proligands and Y(N(SiMe3)2)3 results in the high-yielding preparation and isolation of crystalline, monomeric materials. The complex, tris(N-2',6'-diisopropylphenyl(naphthyl)amidate)yttrium mono(tetrahydrofuran) (4), was structurally determined to be a 7-coordinate C1 symmetric structure, maintaining one bound tetrahydrofuran molecule. Compound 4 (C12H17[NCO]C10H7)3Y(C4H8O) crystallized in the monoclinic space group P2(1)/c with a = 13.