| Abstract
| - A family of new organometallic and coordination compounds supported by a combined imido−diamido−pyridine ligand set are reported. The new compounds were all prepared from the niobium or tantalum complexes shown (M = Nb or Ta; R = tBu or 2,6-C6H3iPr2) and include aryloxide, amide, benzamidinate, alkyl, and cyclopentadienyl derivatives.
- A family of new organometallic and coordination group 5 compounds supported by animido−diamido−pyridine ligand set are reported. Reaction of [M(NR)Cl(κ3-N2Npy)(py)](M = Nb, R = tBu 1; M = Ta, R = tBu 2 or Ar 3, where N2Npy = MeC(2-C5H4N)(CH2NSiMe3)2and Ar = 2,6-C6H3iPr2) with LiOAr or LiPhC(NSiMe3)2 afforded the five-coordinate aryloxideand benzamidinate complexes [M(NR)(OAr)(κ3-N2Npy)] (R = tBu, M = Nb 4 or Ta 5; R = Ar,M = Ta 6) and [Nb(NtBu){PhC(NSiMe3)2}(κ3-N2Npy)] (7), respectively. Reaction of 1 or 2with LiN(SiMe3)2 or LiCH(SiMe3)2 gave the four-coordinate compounds [M(NtBu)(X)(κ2-N2Npy)] (M = Nb, X = N(SiMe3)28 or CH(SiMe3)29; M = Ta, X = CH(SiMe3)210). Reactionof 1 or 2 with the less sterically demanding alkyl reagent LiCH2SiMe3 gave, in the case ofniobium, only the four-coordinate [M(NtBu)(CH2SiMe3)(κ2-N2Npy)] (11), but for tantalum anequilibrium mixture of four- (κ2-) and five- (κ3-) coordinate isomers was identified by NMRspectroscopy. Reaction of 1 with PhCH2MgCl or LiC5H4Me gave the corresponding η1- orη5-hydrocarbyl complexes [Nb(NtBu)(CH2Ph)(κ3-N2Npy)(py)] (13) and [Nb(NtBu)(η5-C5H4Me)(κ2-N2Npy)] (14). The X-ray crystal structures of the compounds 4, 6, and 9 are reported.
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