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Nickel complexes supported by quinoline-based ligands: synthesis, characterization and catalysis in the cross-coupling of arylzinc reagents and aryl chlorides or aryltrimethylammonium salts

2012; Royal Society of Chemistry; Volume: 41; Issue: 34 Linguagem: Inglês

10.1039/c2dt30886j

1477-9234

Qiang Zhang, Xue-Qi Zhang, Zhong-Xia Wang,

Organometallic Complex Synthesis and Catalysis

Lithium and nickel complexes bearing quinoline-based ligands have been synthesized and characterized. Reaction of 8-azidoquinoline with Ph2PNHR (R = p-MeC6H4, But) affords N-(8-quinolyl)iminophosphoranes RNHP(Ph2)N(8-C9H6N) (1a, R = p-MeC6H4; 1b, R = But. C9H6N = quinolyl)). Reaction of 1a with (DME)NiCl2 generates a nickel complex [NiCl2{N(8-C9H6N)P(Ph2)NH(p-MeC6H4)}] (2a). Treatment of 1b with (DME)NiCl2 and following with NaH produces [NiCl{(1,2-C6H4)P(Ph)(NHBut)N(8-C9H6N)}] (4). Complex 4 was also obtained by reaction of (DME)NiCl2 with [Li{(1,2-C6H4)P(Ph)(NHBut)N(8-C9H6N)}] (5) prepared through lithiation of 1b. Reaction of 2-PyCH2P(Ph2)N(8-C9H6N) (6, Py = pyridyl) and PhNC(Ph)CH2P(Ph2)N(8-C9H6N) (8), respectively, with (DME)NiCl2 yields two five-coordinate N,N,N-chelate nickel complexes, [NiCl2{2-PyCH2P(Ph2)N(8-C9H6N)}] (7) and [NiCl2{PhNC(Ph)CH2P(Ph2)N(8-C9H6N)}] (9). Similar reaction between Ph2PCH2P(Ph2)N(8-C9H6N) (10) and (DME)NiCl2 results in five-coordinate N,N,P-chelate nickel complex [NiCl2{Ph2PCH2P(Ph2)N(8-C9H6N)}] (11). Treatment of [(8-C9H6N)NP(Ph2)]2CH2 (12) [prepared from (Ph2P)2CH2 and 2 equiv. of 8-azidoquinoline] with LiBun and (DME)NiCl2 successively affords [NiCl{(8-C9H6N)NP(Ph2)}2CH] (13). The new compounds were characterized by 1H, 13C and 31P NMR spectroscopy (for the diamagnetic compounds), IR spectroscopy (for the nickel complexes) and elemental analysis. Complexes 2a, 4, 7, 9, 11 and 13 were also characterized by single-crystal X-ray diffraction techniques. The nickel complexes were evaluated for the catalysis in the cross-coupling reactions of arylzinc reagents with aryl chlorides and aryltrimethylammonium salts. Complex 7 exhibits the highest activity among the complexes in catalyzing the reactions of arylzinc reagents with either aryl chlorides or aryltrimethylammonium bromides.