179028-86-5Relevant academic research and scientific papers
Reactivity of tantalum hydride aryloxide complexes toward organic isocyanide reagents
Clark, Janet R.,Fanwick, Phillip E.,Rothwell, Ian P.
, p. 3232 - 3237 (1996)
The tantalum monohydride compound [Ta(OC6H3Pri2-2,6) 2Cl2(H)(PMe2Ph)2] (1) reacts with organic isocyanides RNC to produce the phosphine adduct η2-iminoformyl complexes [Ta(OC6H3Pri2-2,6) 2Cl2{HC(PMe2Ph)NR}] (R = 2,6-diisopropylphenyl (2a), 2,6-dimethylphenyl (2b), tert-butyl (2c)). Compounds 2b,c were only detected spectroscopically as intermediates, while 2a was isolated and reacted with PMe3 to produce the complex [Ta(OC6H3Pri2-2,6) 2Cl2{HC(PMe3)NC6H3Pr i2-2,6}] (3), which was structurally characterized. The structure of 3 is best described as trigonal bipyramidal about tantalum with a chloride atom and the phosphine adduct of an η2-iminoformyl group occupying axial sites. Important structural parameters for 3 are Ta-N = 1.956(4), Ta-C = 2.210(5), and N-C = 1.421(7) A?. Compounds 2a and 3 do not react with a further 1 equiv of 2,6-diisopropylphenyl isocyanide. In contrast 2b reacts with 2,6-dimethylphenyl isocyanide to produce the ylide derivative [Ta(OC6H3-Pri2-2,6) 3Cl2{RN=CHC(=PMe2Ph)NR}] (4) (R = C6H3Me2-2,6), while 2c reacts with an additional 2 equiv of ButNC to produce the compound [Ta(OC6H3Pri2-2,6) 3Cl2{ButN=CHC-(=C=NBut)NBu t}] (5). Spectroscopic data on 4 and 5 and a single-crystal X-ray diffraction study of 5 show both molecules contain 2,5-diazacyclopent-2-ene rings with either ylide (4) or keteneimine (5) groups attached to the C-4 position. Addition of ButNC to 2a produces the complex [Ta(OC6H3Pri2-2,6) 2Cl2{RN=CHC(=C=NBut)NBut}] (6) (R = C6H3Pri2-2,6). The tantalum dihydride compound [Ta(OC6H3But2,-2,6) 2Cl2(H)(PMePh2)] (7) reacts with RNC to produce the monocyclometalated derivatives [Ta(OC6H3BUt-CMe2CH 2)(OC6H3BUt2-2,6)-Cl 2{N(R)CH3}] (8) (a, R = C6H3Me2-2,6; b, R = But), in which a total of three hydride groups have been transferred to the isocyanide substrate to produce the dialkylamido ligand.
