The following crystalline oligonuclear metal alkyls have been synthesised under mild conditions and structurally characterised: [(THF)Li(μ-A)(μ-Cl)(μ3-OMe)Zn]2
(3), [Li(μ-A)2Tl]2
(4 and 4â²), [Li4(μ-A)3(μ3-OMe)]
(5), [(μ-A)Li2(μ-A)2(μ3-OMe)Ce(A)]
(6) and [Ce(A)(μ2-OMe)μ2-OS(O)(CF3)O}]2
(11)
[A
= CH(SiMe3)SiMe(OMe)2}]. Compounds 2â6 were obtained from [Li(μ-A)]â
(1) and ZnCl2
(3), TlCl (4 and 4â² and 5) and CeCl3
(6), and 11 was isolated from K(A)
(prepared from 1
+ KOBut) and cerium(III) triflate Ce(OTf)3. The principal novel features are (i) and (ii) as follows. As for (i), the diversity of ligand-to-metal bonding is noteworthy, the ligand being (a)
C,O-bridging in 3
as in the known compounds 1 and in [Li2Mg5(μ3-OMe)6(μ2-OMe)2(μ2-A)4]
(2)}; (b)
C,O,Oâ²-bridging and O,Oâ²-chelating in 4 and 4â²; (c)
C,O,Oâ²-bridging in 5; (d)
C,O,Oâ²-bridging and C,O-chelating in 6; and (e)
C,O-chelating in 11. Regarding (ii), it is interesting that the ligand [A]â is surprisingly ready to undergo fragmentation by SiâOMe cleavage and thereby present bridging methoxy ligands (μ2-OMe)2 to a pair of Ce3+ ions in 11, or μ3-OMe acting as a cap for triangular arrays of three hard metal ions (Mg3 in 2, LiZn2 in 3, Li3 in 5, and Li2Ce in 6).
以下晶体状的多核
金属烷基化合物在温和条件下合成并进行了结构表征:[(THF)Li(μ-A)(μ-Cl)(μ3-OMe)Zn]2 (3)、[Li(μ-A)2Tl]2 (4 和 4′)、[Li4(μ-A)3(μ3-OMe)] (5)、[(μ-A)Li2(μ-A)2(μ3-OMe)Ce(A)] (6) 和 [Ce(A)(μ2-OMe)μ2-
OS(O)(
CF3)O}]2 (11) [A = CH(SiMe3)SiMe(OMe)2}]。化合物2–6由[Li(μ-A)]∞ (1) 和ZnCl2 (3)、TlCl (4 和 4′以及5)及
CeCl3 (6) 合成,而11是通过K(A) (由1 + KOBut制备)和
铈(III)三
氟甲烷磺酸盐Ce(OTf)3分离得到的。主要的新特征如下:(i)和(ii)。关于(i),值得注意的是
配体与
金属的结合多样性,
配体为(a)在3中C,O-桥接如已知化合物1和[Li2Mg5(μ3-OMe)6(μ2-OMe)2(μ2-A)4] (2)中一样};(b)在4和4′中C,O,O′-桥接和O,O′-螯合;(c)在5中C,O,O′-桥接;(d)在6中C,O,O′-桥接和C,O-螯合;以及(e)在11中C,O-螯合。关于(ii),有趣的是
配体[A]−意外地容易通过Si–OMe断裂而发生碎裂,从而向11中的一对Ce3+离子提供桥接的甲
氧基
配体(μ2-OMe)2,或μ3-OMe作为三个硬
金属离子(三角排列,2中的Mg3,3中的
LiZn2,5中的Li3,以及6中的Li2Ce)的帽。