NEUTRAL AND CATIONIC GROUP-4 METAL-COMPOUNDS CONTAINING OCTAMETHYLDIBENZOTETRAAZAANNULENE (ME(8)TAA(2-)) LIGANDS - SYNTHESIS AND REACTIVITYOF (ME(8)TAA)MX2 AND (ME(8)TAA)MX+ COMPLEXES (M = ZR, HF, X = CL, HYDROCARBYL, NR2, OR)

The synthesis and reactivity of out-of-plane (Me(8)taa)MX2 and (Me(8)t aa)MX+ complexes (M = Zr, Hf; X = Cl, hydrocarbyl, NR2, OR) containing the dianionic tetraaza-macrocycle ligand octamethyldibenzotetraazaann ulene (Me(8)taa(2-)) are described. The reaction of [Li(Et2O)]2[Me(8)t aa] (1) with MCl4(THF)(2) yields (Me(8)taa)MCl2 complexes (2a, M = Zr; 2b, M = Hf). Alkylation of 2a,b with LiCH2SiMe3 or LiMe in hydrocarbo n solvents yields (Me(8)taa)M(CH2SiMe3)(2) (3a, M = Zr; 4a, M = Hf) or (Me(8)taa)MMe2 (3b, M = Zr; 4b, M = Hf) complexes. Compound 3b rearra nges by migration of a Me group from Zr to a Me(8)taa imine carbon in coordinating solvents. The reaction of (Me(8)taa)H-2 with the appropri ate ZrR4 compound yields (Me(8)taa)Zr(CH2Ph)(2) (3c) and (Me(8)taa)Zr( CH2CMe3)(2) (3d). The reaction of (Me(8)taa)H-2 and Zr(NR2)(4) yields (Me(8)taa)Zr(NR2)(2) (6a, R = Me; 6b, R = Et). Spectroscopic data for (Me(8)taa)MX2 compounds 2, 3, 4, and 6 are consistent with cis, C-2 up silon-symmetric structures, Dialkyl complexes 3 and 4 and bis(amide) c omplexes 6 react with chlorinated solvents (1,1,2,2-tetrachloroethane, CH2Cl2) to yield 2. Compound 6a reacts with AlMe3 to afford the heter obimetallic mu-amido complex [(Me(8)taa)Zr(mu-NMe2)(2)AlMe2][AlMe4] (8 ), which does not undergo further reaction iu yield 3b. The reaction o f dialkyl complexes 3 and 4a with HNR3+ reagents yields cationic [(Me( 8)taa)MR][B(C6F5)(4)] compounds (10a, M = Zr, R = eta(2)-CH2Ph; 10b, M = Zr, R = CH2SiMe3; 10c, M = Zr; R = CH2CMe3; 10d, M = Hf, R = Me). T hese species form labile adducts with PMe2Ph and THF. Cation 10a polym erizes ethylene to a linear polymer with low activity, while 10d is un reactive with ethylene. 10a reacts with HOCMe2CH2CH2CH=CH2 to yield th e mononuclear alkoxide complex (Me(8)taa)Zr(OCMe2CH2CH2CH=CH2)(+) (13) , in which the pendant alkene not coordinated. 10a also reacts with wa ter or ethanol to yield binuclear complexes [{(Me(8)taa)Zr(mu-OR)}(2)] (2+) (14a, R = H; 14b, R = Et). An X-ray structural analysis of 14a re veals that one of the (Me(8)taa)Zr units has an unusual inverted confo rmation, and NMR data suggest that 14a,b adopt similar structures in s olution. 10d reacts with 2-butyne to yield the double insertion produc t [(Me(8)taa)Hf(CMe=CMeCMe=CMe2)](+) (15) and with MeC=CSiMe3 to affor d [(Me(8)taa)Hf(C(SiMe3)=CMe2)](+) (16), while 10a and 10b are unreact ive with these alkynes. 10a and 10c react with terminal alkynes by pro tonolysis to afford binuclear [{Me(8)taa)Zr(mu-C=CR)}(2)](2+) complexe s (17a, R = Ph; 17b, R = Pr). Complex 17a reacts reversibly with PMe3 to yield the mononuclear cation (Me(8)taa)Zr(C=CPh)(PMe3)(+) (18a). (M e(8)taa)MR+ species are less reactive for alkene and alkyne insertion than are Cp2MR+ species.