Flexible Building Blocks for Transition Metal Early−Late Chemistry. Synthesis of Heterobimetallic Tetranuclear Metallomacrocycles
摘要:
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 [Cp-2(tt)-ZrMe2] (Cp-tt = eta(5)-1,3-di-tert-butylcyclopentadienyl) stops at the complex [(Cp2ZrMe)-Zr-tt(OCH2-PPh2)] (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(mu-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 d(0)-d(8) early-late heterobimetallic (ELHB) metallomacrocycles [Cp2M(OCH2PPh2)(2)Ir(cod)](2)(2+) (M = Zr (7), Ti (8)) and [Cp2Zr(mu-OCH2PPh2)(2)Rh(nbd)](2)(2+) (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.
Metallatriphos complexes: synthesis and molecular structure of [TpZr(OCH2PPh2)3] (Tp=tris(pyrazolyl)hydroborate) and formation of the heterodinuclear complex [TpZr(μ-OCH2PPh2)3Mo(CO)3] with bridging phosphinoalkoxide ligands
[TpZr(OCH2PPh2)(3)] (1) is obtained from [TpZrCl(3)] and LiOCH2PPh2 in THF. Complex 1 reacts with [Mo(CO)(3)(NCEt)(3)] to give the heterodinuclear complex [TpZr(mu -OCH2PPh2)(3)Mo(Co)(3)] (2). Complexes 1 and 2 were characterised spectroscopically. Crystal structure determinations were carried out on 1 and on HOCH2PPh2. The former showed that the lone pairs of the P atoms appear to be suited ideally for coordination to a second metal centre. (C) 2001 Elsevier Science Ltd. All rights reserved.