Oxo-Bridged Bis(group 4 metal unsymmetric phosphonium-stabilized carbene) Complexes

The
synthesis and reactivity of oxo-bridged bis­(group 4 metal unsymmetric
phosphonium-stabilized carbene) complexes are described. The reaction
of [CH2RNRS] (1; RN = PPh2NSiMe3, RS = PPh2S) with 1 equiv of [M­(NMe2)4] (M = Zr,
Hf) afforded the group 4 metal unsymmetric phosphonium-stabilized
carbene complexes [M­(NMe2)2(CRNRS)] (M = Zr (4), Hf (5)). Their reactions
with water in toluene afforded the oxo-bridged derivatives O­[M­(NMe2)­(CRNRS)]2 (M = Zr (6), Hf (7)). Compound 6 underwent
an insertion reaction with AdNCO to form O­[Zr­{OC­(NMe2)­NAd}­(CRNRS)]2 (8; Ad = adamantyl).
Compounds 4–8 were characterized
by NMR spectroscopy and X-ray crystallography.

本文报道了氧桥联双（第4族金属（group 4 metal）不对称鏻稳定卡宾（phosphonium-stabilized carbene））配合物的合成与反应性。配体[CH2RNRS]（1；其中RN = PPh2NSiMe3，RS = PPh2S）与1当量的[M(NMe2)4]（M=锆（Zr）、铪（Hf））反应，合成得到第4族金属不对称鏻稳定卡宾配合物[M(NMe2)2(CRNRS)]（M=Zr（4）、Hf（5））。该类配合物在甲苯中与水反应，生成氧桥联衍生物O[M(NMe2)(CRNRS)]2（M=Zr（6）、Hf（7））。化合物6与异氰酸金刚酯（AdNCO，Ad=金刚烷基（adamantyl））发生插入反应（insertion reaction），得到O[Zr{OC(NMe2)NAd}(CRNRS)]2（8）。最后，采用核磁共振波谱法（NMR spectroscopy）与X射线晶体衍射（X-ray crystallography）对化合物4~8进行了表征。