Flexible Building Blocks for Transition Metal Early−Late Chemistry. Synthesis of Heterobimetallic Tetranuclear Metallomacrocycles

The reaction of LiOCH2PPh2 with the metallocene compounds [Cp2MCl2] yields the
metallodiphosphines [Cp2M(OCH2PPh2)2] (M = Ti (1), Zr (2)). Compound 2 has also been
prepared by reaction of HOCH2PPh2 with [Cp2ZrMe2], although the reaction with [Cptt2ZrMe2] (Cptt = η5-1,3-di-tert-butylcyclopentadienyl) stops at the complex [Cptt2ZrMe(OCH2PPh2)] (3). The mononuclear late transition metal complexes containing (diphenylphosphanyl)methanol ligands, cis-[M(cod)(Ph2PCH2OH)2]BF4 (M = Rh (4), Ir (5)) and cis-[Pt(p-tolyl)2(Ph2PCH2OH)2] (6), have been prepared by reaction of [M(cod)(NCCH3)2]BF4 and [Pt(μ-SEt2)(p-tolyl)2]2 with HOCH2PPh2. The reaction of the metallodiphosphines 1 and 2 with
the compounds [M(diolef)(NCCH3)2]BF4 (M = Rh, Ir) afforded the tetranuclear d0−d8 early−late heterobimetallic (ELHB) metallomacrocycles [Cp2M(OCH2PPh2)2Ir(cod)]22+ (M = Zr (7),
Ti (8)) and [Cp2Zr(μ-OCH2PPh2)2Rh(nbd)]22+ (9). The crystal structures of the 16-membered
metallomacrocycles 7 and 9 have been determined by X-ray diffraction and show a rhomboidal
arrangement of the metal centers with a conformation that is largely determined on steric
grounds.

LiOCH₂PPh₂与茂金属化合物[Cp₂MCl₂]（Cp为环戊二烯基（cyclopentadienyl，Cp））反应，可生成金属双膦配合物[Cp₂M(OCH₂PPh₂)₂]（M为钛（Ti，产物1）、锆（Zr，产物2））。配合物2亦可通过HOCH₂PPh₂与[Cp₂ZrMe₂]的反应制备；但当使用[Cptt₂ZrMe₂]（Cptt为η⁵-1,3-二叔丁基环戊二烯基（η⁵-1,3-di-tert-butylcyclopentadienyl））进行反应时，反应仅停留在配合物[Cptt₂ZrMe(OCH₂PPh₂)]（3）阶段。含二苯基膦基甲醇配体的单核后过渡金属配合物cis-[M(1,5-环辛二烯（cyclooctadiene，cod）)(Ph₂PCH₂OH)₂]BF₄（M为铑（Rh，4）、铱（Ir，5））与cis-[Pt(p-甲苯基)₂(Ph₂PCH₂OH)₂]（6），可通过[M(cod)(NCCH₃)₂]BF₄、[Pt(μ-二乙硫基（μ-SEt₂）)(p-甲苯基)₂]₂与HOCH₂PPh₂的反应制备。
金属双膦配合物1和2与[M(二烯烃（diolefin，diolef）)(NCCH₃)₂]BF₄（M为Rh、Ir）发生反应，得到四核d⁰−d⁸型早-晚异双金属（early−late heterobimetallic，ELHB）金属大环[Cp₂M(OCH₂PPh₂)₂Ir(cod)]₂²⁺（M为Zr（7）、Ti（8））与[Cp₂Zr(μ-OCH₂PPh₂)₂Rh(降冰片二烯（norbornadiene，nbd))]₂²⁺（9）。通过X射线衍射（X-ray diffraction）测定了16元金属大环7与9的晶体结构，结果显示其金属中心呈菱形排布，构象主要由空间位阻因素决定。