MONONUCLEAR AMIDO AND BINUCLEAR IMIDO ZIRCONIUM COMPLEXES SUPPORTED BY DIBENZOTETRAAZA[14]ANNULENE LIGANDS - X-RAY STRUCTURE OF [(ME(4)TAA)ZR(MU-NR)(2)ZR(NHR)(2)] (R=BU(T) OR 2,6-C(6)H(3)ME(2))

Reaction of 2 equiv of Li[NH-2,6-C(6)H(3)R(2)] with [(Me(4)taa)ZrCl2] (Me(4)taaH(2) = tetramethyldibenzotetraaza[14]-annulene) gives the bis (amido) derivatives [(Me(4)taa)Zr(NH-2,6-C(6)H(3)R(2))(2)] [R = Pr-i ( 1) and Me (2)]. Addition of Me(4)taaH(2) to [Zr(N-2,6-C6H3Pr2i)(NH-2,6 -C6H3Pr2i)(2)(py)(2)] also affords 1. The reaction of 2 equiv of aryl or alkyl amines H(2)NR with the bis(alkyl) complex [(Me(4)taa)Zr(CH(2) SiMe(3))(2)] is the most versatile method for preparing [(Me(4)taa)Zr( NHR)(2)] (R = 2,6-C6H3Pr2i, 2,6-C(6)H(3)Me(2), Ph, or Bu(t)). Reaction of 1 equiv of Me(4)taaH(2) with the binuclear complexes [(Bu(t)NH)(2) Zr(mu-NBu(t))(2)Zr(NHBu(t))(2)] or C(6)H(3)Me(2))(2)Zr-(NH-2,6-C(6)H(3 )Me(2))(2)(py)] gives the asymmetrically substituted derivatives [(Me( 4)taa)Zr(mu-NR)(2)Zr(NHR)(2)] [R = Bu(t) (6) or 2,6-C(6)H(3)Me(2) (8)] , which have been crystallographically characterized.