|Budget Amount *help
¥14,200,000 (Direct Cost: ¥14,200,000)
Fiscal Year 2003: ¥4,400,000 (Direct Cost: ¥4,400,000)
Fiscal Year 2002: ¥4,400,000 (Direct Cost: ¥4,400,000)
Fiscal Year 2001: ¥5,400,000 (Direct Cost: ¥5,400,000)
Recently we have found the novel reaction of a tungsten dinitrogen complex with acidic ruthenium η^2-dihydrogen complexes to form ammonia under mild conditions, although the reaction is stoichiometric.
In this project, we have paid our attention to late transition metal complexes by which both dinitrogen and dihydrogen are bound and activated.Our purpose is to develop the nitrogen fixation catalytic cycle in which dihydrogen is used for protonation and reduction of the coordinated dinitrogen on a metal complex. We have investigated synthesis and reactivity of late transition-metal complexes containing tridentate diamidoAbloether(NSN-type), diamido/phosphine(NPN-type), and diamido/amine(NNNAype)ligands.Although dinitrogen complexes could not be isolated, the IR spectrum-of a reaction solution showed the formation of [Ru(NSN)(PMe_3)_2(N≡N)], but hydrogenation of dinitrogen did not proceed.However, we have found the catalytic hydrogenation of benzonitnle, an isoelectronic molecule of dinit
rogen, by employing those metal complexes containing tridentate amido ligands.
On the other hand, the chemistry of multimetallic sulfido clusters has been receiving much attention in relevance to the active sites of nitrogenase. We have long aimed at construction of polynuclear metal-sulfur reaction sites, the stnictures of which are carefully controlled at molecular levels.In this study, cubane-type clusters having a [Mo_3MS_4] (M=Ru, Rh, Ni, Pd, Pt)core were prepared and their reactivities were investigated.The disproportionation reaction of hydrazine proceeded to form ammonia and dinitrogen, when [(Cp^^*Mo)_3(η^3-S)_4RuH_2(PAr_3)](Ar=Ph, p-tolyl)was reacted with hydrazine.Although attempts to prepare[Mo_3RuS_4]clusters binding dinitrogen on ruthenium have failed, [Mo_3NiS_4]clusters showed novel catalytic activity for the cyclization of alkynoic acids to enol lactones, which was not catalyzed by mononuclear Ni complexes.Further, [Mo_3MS_4](M=Pd, Ru)clusters exhibited higher catalytic activity than mononuclear Pd or Ru complexes for the intramolecular hydroamination of aminoalkynes. Less