Synthesis, structure, and reactivity of β-diketiminate boron(III) complexes
1999; Elsevier BV; Volume: 18; Issue: 18 Linguagem: Inglês
10.1016/s0277-5387(99)00137-0
ISSN1873-3719
AutoresBaixin Qian, Sung W. Baek, Milton R. Smith,
Tópico(s)Coordination Chemistry and Organometallics
ResumoThe chemistry of boron supported by the β-diketiminate ligand, tolylnacnac (tolylnacnacH=2-N-p-tolylamino-4-N-p-tolylimino-2-pentene), has been investigated. (tolylnacnac)Li reacted with one equivalent of BF3·OEt2 to afford (tolylnacnac)BF2 (1) in 46% yield. The structure of compound 1 was solved indicating that the diketiminate ligand is η2-bound to B to form a six-membered heterocycle. While alkylation of compound 1 can be effected with alkyl lithium or Grignard reagents, nucleophilic addition to the diketiminate ligand occurred in the reaction between compound 1 and MeLi to afford [η2-(Me)2C(Ntolyl)CHC(Ntolyl)Me]BMe (2). For Me3SiCH2Li, deprotonation of the diketiminate ligand afforded [η2-CH2C(Ntolyl)CHC(Ntolyl)Me]BCH2SiMe3 (3). Conversely, alkyl Grignard reagents selectively delivered two alkyl groups to the boron center, and several pseudo-tetrahedral (tolylnacnac)BR2 (4a–d; a, R=Me, b, R=nPr, c, R=vinyl, d, R=allyl) complexes have been prepared. The structures of compounds 2, 3, and 4a were solved, and variations in B–N and B–C metrical data for compounds 2 and 4a were correlated to bond order, inductive effects of the co-ligands, and hybridization of the boron center. The reaction between compound 4a and tris(pentafluorophenyl)boron gave [(tolylnacnac)BMe]+[MeB(C6F5)3]− (5). Compound 5 reacted with pyridine to give an adduct, [(tolylnacnac)B(py)Me]+[MeB(C6F5)3]− (6).
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