Synthesis and structural characterization of new organo-diimido and organo-imido niobium and titanium complexes

摘要

The organo-diimido complexes [{Nb(L-2)Cl-3}(2)(mu-1,4-NC6H4N)], L=CH3CN 1a or 4-(t)Bupy 2a, [{Nb(L-2)Cl-3}(2)(mu-1,3-NC6H4N)], L=CH3CN 1b or 4-(t)Bupy 2b, and [{Nb(L-2)Cl-3}(2)(mu-1,2-NC6H4N)], L=CH3CN 1c or 4-(t)Bupy 2c were isolated by treating NbCl5 in the presence of CH3CN or 4-(t)Bupy with the appropriate amount of the corresponding aniline N,N,N',N'-tetrakis(trimethylsilyl)-1,4-, -1,3-, or -1,2-phenylenediamine, respectively. Compound 1a reacts with appropriate alkylating reagents to give the corresponding alkyl complexes, namely [{NbLR3}(2)(mu-1,4-NC6H4N)], L=CH3CN, R=CH2SiMe3 3a; or CH2CMe3 3b; L=THF, R=CH2SiMe3 4a or CH2CMe3 4b. The crystal structure determination of 3a was carried out. Reaction of [Ti(py)(3)Cl-2((NBu)-Bu-t)] with N,N,N',N'-tetramethyl-1,4-phenylenediamine, in 2:1 or 1:1 stoichiometric ratio, afforded the organo-imido complexes [Ti(py)(n)Cl-2(1,4-NC6Me4NH2)], n=3 (5a) or 2 (5b), while analogous reactions with 1,4- or 1,3-phenylenediamine give intractable mixtures of products. Organo-imido and organo-diimido titanium complexes were easily prepared by treating TiCl4 with the appropriate N,N,N',N'-tetrakis(trimethylsilyl)phenylenediamines in CH2Cl2 in 1:1 and 2:1 molar ratios in the presence of 4-tert-butylpyridine or N,N,N',N'-tetramethylethylenediamine (TMEDA). The compounds prepared in this way are [Ti(4-(t)Bupy)(2)Cl-2{1,4-NC6H4N(SiMe3)(2)}] 6a, [Ti(TMEDA)Cl-2{1,4-NC6H4N(SiMe3)(2)}] 6b, [Ti(TMEDA)Cl-2{1,3-NC6H4N(SiMe3)(2)}] 7b, [{Ti(4-(t)Bupy)(2)Cl-2}(2)(mu-1,4-NC6H4N)] 8a, [{Ti(TMEDA)Cl-2}(2)(mu-1,4-NC6H4N)] 8b, [{Ti(4-(t)Bupy)(2)Cl-2}(2)(mu-1,3-NC6H4N)] 9a and [{Ti(TMEDA)Cl-2}(2)(mu-1,3-NC6H4N)] 9b. Finally, the same reaction with N,N,N',N'-tetrakis(trimethylsilyl)-1,2-phenylenediamine, in the presence of 4-(t)Bupy or TMEDA, gives the diamido complexes [Ti(4-(t)Bupy)(2)Cl-2{1,2-C6H4(NH)(2)}] 10a and [Ti(TMEDA)Cl-2{1,2-C6H4(NH)(2)}] 10b. The structures of the different families of complexes were determined by spectroscopic methods. [References: 17]