화학공학소재연구정보센터
Inorganic Chemistry, Vol.46, No.21, 8836-8842, 2007
Dinitrogen coordination and cleavage promoted by a vanadium complex of a sigma,pi,sigma-donor ligand
The deprotonation of the tripyrrole MeTPH2 [MeTPH2 = 2,5-[(2-pyrrolyl)(C6H5)(2)C](2)(MeNC4H2)], containing one N-methylated pyrrolyl ring, was carried out with 2 equiv of KH. The corresponding dipotassium salt reacted with VCl3(THF)(3) to afford the complex [(MeTP)VCl(THF)]center dot THF (1). While the two lateral pyrrolide rings are sigma-bonded, the central one is perpendicularly oriented in a sort of pi-fashion. However, the bond distances clearly indicated that only the quaternized N atom is forming a bonding contact. Subsequent reduction of 1 with Na yielded the corresponding divalent complex [(MeTP)V(THF)]center dot(C7H8)(0.5) (2) where the central N-methylated ring adopted a more regular pi-orientation. When treated with a strong Lewis acid (AIMe(3)) THF was extracted from the vanadium coordination sphere, forming the dinuclear dinitrogen complex [(MeTP)V(mu-N-2)](2)center dot(C7H8)(2.9) (3). Reduction of 3 with potassium graphite gave cleavage of dinitrogen, affording the mixed-valent nitride-bridged complex [(MeTP)V(mu-N)](2)-(THF) (4).