Bis(mesitylen)niobium(0), Nbmes2, prepared via the NbCl5/Al/AlCl3/mes system by exaustive reduction in the presence of 1,2-dimethoxyethane or tetrahydrofuran as previously reported, has been studied by X-ray diffraction methods. The sandwich molecule has parallel, substantially planar, aromatic rings, in an eclipsed conformation. Nbmes2 is oxidized to Nbmes2X by reaction with 1,1'-dimethyl-4,4'-bipyridinium halides [methylviologen halides, MvX2 (X = Cl, I)]. The reaction of both halo compounds with CO yielded the niobium(I) derivatives [Nbmes2(CO)] [Nb2(mu-X)3(CO)8]. In the case of X = I an IR study at low temperature has shown the presence of intermediate carbonyl compounds, presumably Nbmes2I(CO) and [Nbmes2(CO)]+. The ionic iodide derivative was shown by X-ray diffraction methods to consist of discrete [Nbmes2(CO)]+ cations and [Nb2(mu-I)3(CO)8]- anions. The two mesitylene groups in the cation are bent and in an eclipsed conformation.
SYNTHESIS AND REACTIVITY OF MIXED ARENE HALIDES OF NIOBIUM(I) - CRYSTAL AND MOLECULAR-STRUCTURE OF NBMES2 AND [NBMES2(CO)][NB2(MU-I)3(CO)8]
CALDERAZZO, FAUSTO;PAMPALONI, GUIDO;
1992-01-01
Abstract
Bis(mesitylen)niobium(0), Nbmes2, prepared via the NbCl5/Al/AlCl3/mes system by exaustive reduction in the presence of 1,2-dimethoxyethane or tetrahydrofuran as previously reported, has been studied by X-ray diffraction methods. The sandwich molecule has parallel, substantially planar, aromatic rings, in an eclipsed conformation. Nbmes2 is oxidized to Nbmes2X by reaction with 1,1'-dimethyl-4,4'-bipyridinium halides [methylviologen halides, MvX2 (X = Cl, I)]. The reaction of both halo compounds with CO yielded the niobium(I) derivatives [Nbmes2(CO)] [Nb2(mu-X)3(CO)8]. In the case of X = I an IR study at low temperature has shown the presence of intermediate carbonyl compounds, presumably Nbmes2I(CO) and [Nbmes2(CO)]+. The ionic iodide derivative was shown by X-ray diffraction methods to consist of discrete [Nbmes2(CO)]+ cations and [Nb2(mu-I)3(CO)8]- anions. The two mesitylene groups in the cation are bent and in an eclipsed conformation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
