full title: Synthesis and structure of [Zr(R)Cl(η-C5H5)2] [r = chiral, highly hindered alkyl: C̄HSiMe3C5H4N̈-2, C̄HSiMe3C6H4P̈Ph2-o, or C̄HSiMe3(C14H9-9)]; influence of the functional group on the nature and stability of their d1 reduction products Reaction of [ZrCl2(η-C5H5)2] with organolithium reagents Li(tmen)(Rn) [Rn = a highly hindered alkyl, C̄HSiMe3C5H4N̈-2 (R1), C̄HSiMe3C6H4P̈Ph2-o (R2), C̄HSiMe3(C14H9-9) (R3) (C14H9 = anthryl), or C̄HSiMe3(C6H4Me-p) (R4); tmen = Me2NCH2CH2NMe2] in tetrahydrofuran (thf) yields [Zr(Rn)Cl(η-C5H5)2], compounds (2), (4), (6), and (8), respectively. Electrochemical reduction of (6) is reversible (10 < t1/2 ≲ 50s) whereas for (2), (4), and (8) it is irreversible. Reduction of (2) and (4) yields chloride-free persistent d1 species, respectively [Zr(R1)(η-C5H5)2], with R1 chelating or η3-aza-allyl, and [Zr(CHSiMe3C6H4PPh2-o)(η-C 5H5)2] (31P coupling) either in thf (Na[C10H8]) or toluene (Na/Hg). Reduced (2), (4), (6), and (8) react with PMe3 yielding d1 [Zr(Rn) (PMe3)(η-C5H5)2]. Variable-temperature 1H n.m.r. investigation of (2) in toluene shows an equilibrium between four- and five-co-ordinate complexes; in the solid the latter prevails with a Zr-N distance of 2.341 Å, and an exceptionally long Zr-Cl distance (2.563 Å). In (4) the functional group is not bound to the metal centre [Zr-Cl 2.438(1), Zr-C 2.350(4) Å] and in (6) the potentially ambidentate alkyl R3 is bound through the benzylic carbon [Zr-C 2.349(4), Zr-Cl 2.454(1) Å].
|Number of pages||11|
|Journal||Journal of the Chemical Society, Dalton Transactions|
|Publication status||Published - 1986|