Metal phosphinohydrazone complexes
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Metal phosphinohydrazone complexes Yu. S. Panova, A. V. Sheyanova, V. V. Sushev, N. V. Zolotareva, A. V. Cherkasov, and A. N. Kornev G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, 49 ul. Tropinina, 603137 Nizhny Novgorod, Russian Federation. Fax: +7 (831) 462 7497. E-mail: [email protected] The reaction of benzophenone hydrazone with chlorodiphenylphosphine in the presence of triethylamine affords the monophosphino derivative Ph2C=N—N(H)PPh2 (1). The lithiation of 1 with one equivalent of MeLi produces the stable salt Ph2C=N—N(Li)PPh2, and the addition of the second equivalent of MeLi results in the lithiation of the aromatic ring of the Ph2C group followed by the cyclization to lithium-substituted diazaphosphinine. The treatment of the latter with chlorotrimethylsilane furnishes 1,4-diphenyl-2-trimethylsilyl-1,2-dihydrobenzo[d][1,2,3]diazaphosphinine. Phosphinohydrazone 1 gives 2 : 1 complexes with cobalt and nickel bromides, which were characterized by X-ray diffraction. The migratory insertion of the Ph2P group into the N—N bond was not observed in phosphinohydrazone derivatives, as opposed to phosphinohydrazides M—NR—NR—PPh2 (M is metal). Key words: hydrazones, phosphinohydrazones, phosphine complexes, azaphosphinines, cobalt complexes, nickel complexes.
The term "phosphinohydrazones" combines several types of compounds with different functionality. The most representative type includes chelating N,P-ligands containing phosphine and hydrazone groups linked by a carb on chain.1—9 These ligands are successfully used in different catalytic processes.1—8 Another type of compounds includes pentavalent phosphorus compounds of the general formula R2C=NN(R´)P(X)R2, where X = O, S, containing a P—N bond.10—12 In compounds belonging to the third, least characterized, type of phosphinohydrazones, the hydrazone group is directly bonded to the phosphine group. A single representative of these compounds was prepared by the reaction of phosphinoboranes with diazomethane derivatives.13 Our interest in the third type of phosphinohydrazones is due to systematic research into rearrangements in systems containing a PIII—N—N chain. Previously, we have studied in detail the phosphinohydrazide systems {(M—N(R1)—N(R2)—PR32)} containing metal atoms of different nature (alkali metals, transition metals, main-group metals, lanthanides). Under particular conditions, these systems were shown to be prone to rearrangements accompanied by the insertion of the R2P group into a nitrogen—nitrogen bond. Several types of these rearrangements giving iminophosphoranate, amidophosphine, and phosphazene moieties (I, II, and III, respectively) were described in the literature.14—18 The formation of a pentavalent four-coordinate phosphorus atom is the driving force for these transformations (Scheme 1).
Scheme 1
M is metal.
Meanwhile, it is known that metal complexes with uncharged bidentate phosphinohydrazide ligands M(R2P— NRNR—PR2)18—21 are thermodynamically stable, like carbon analogs M(R2P—CH2CH2—PR
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