Metal Complexes of New, Chiral N2O2 Tetradentate Ligands
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- 作者：Ronald J. Cross ; Louis J. Farrugia ; Paul D. Newman ; Robert D. Peacock ; and Diane Stirling
- 刊名：Inorganic Chemistry
- 出版年：1999
- 出版时间：March 22, 1999
- 年：1999
- 卷：38
- 期：6
- 页码：1186 - 1192
- 全文大小：135K
- 年卷期：v.38,no.6(March 22, 1999)
- ISSN：1520-510X
文摘
N,N'-Bis(2R-hydroxy-2R-phenylethyl)-N,N'-dimethyl-1R,2R-diaminocyclohexane, H2L1, and N,N'-bis(2S-hydroxy-2S-methylethyl)-N,N'-dimethyl-1R,2R-diaminocyclohexane, H2L2, have been synthesized from readily availablechiral precursors. They coordinate as neutral tetradentate ligands to Ni(II) and Cu(II) ions, from which thethiocyanates [M(H2L)(NCS)2] have been isolated and the structures of the H2L1 complexes determined by single-crystal X-ray techniques. In the blue complex [Ni(H2L1)(NCS)2]·H2O·2EtOH, 1, and green [Cu(H2L1)(NCS)2]·0.5H2O, 2, the neutral tetradentate ligands coordinate with the cis-
geometry with mutually cis N-bound thiocyanategroups, though the chiral ligands adopt a different stereochemistry in the two complexes. In 2, the absoluteconfiguration about the Cu(II) center is 
, with the nitrogens possessing the S stereochemistry, whereas for theNi(II) analogue, coordination gives the 
isomer with the R configuration at the stereogenic nitrogens. Additionof H2L1 or H2L2 to Mn(II) in basic methanol solution results in rapid aerial oxidation. -cis--[Mn(L1)(OMe)2]·MeOH, 3, was isolated as black crystals from the reaction mixture after addition of 2 mol of NaOMe. The analogouscomplex with (L2)2- proved extremely hygroscopic and was not obtained in pure form. Colorless crystals of-cis--[MoO2(L1)], 4, were precipitated from a methanolic solution of [MoO2(acac)2] and H2L1. The analogousreaction with H2L2 gave -cis--[MoO2(L2)], 5. Structures of 3, 4, and 5 are reported. The reactions of H2L1and H2L2 with 1 mol equiv of [Ti(OPri)4] produced the complexes -cis--[Ti(L1)(OPri)2] (white solid) and-cis--[Ti(L2)(OPri)2] (colorless oil), structural assignments for which were made possible by analysis of their1H NOE difference spectra. Thus the coordination of these tetradentate ligands is stereospecific, but the absoluteconfiguration of the complexes formed ( or ) is dependent on the metal ion involved.
geometry with mutually cis N-bound thiocyanategroups, though the chiral ligands adopt a different stereochemistry in the two complexes. In 2, the absoluteconfiguration about the Cu(II) center is , with the nitrogens possessing the S stereochemistry, whereas for theNi(II) analogue, coordination gives the isomer with the R configuration at the stereogenic nitrogens. Additionof H2L1 or H2L2 to Mn(II) in basic methanol solution results in rapid aerial oxidation. -cis--[Mn(L1)(OMe)2]·MeOH, 3, was isolated as black crystals from the reaction mixture after addition of 2 mol of NaOMe. The analogouscomplex with (L2)2- proved extremely hygroscopic and was not obtained in pure form. Colorless crystals of-cis--[MoO2(L1)], 4, were precipitated from a methanolic solution of [MoO2(acac)2] and H2L1. The analogousreaction with H2L2 gave -cis--[MoO2(L2)], 5. Structures of 3, 4, and 5 are reported. The reactions of H2L1and H2L2 with 1 mol equiv of [Ti(OPri)4] produced the complexes -cis--[Ti(L1)(OPri)2] (white solid) and-cis--[Ti(L2)(OPri)2] (colorless oil), structural assignments for which were made possible by analysis of their1H NOE difference spectra. Thus the coordination of these tetradentate ligands is stereospecific, but the absoluteconfiguration of the complexes formed ( or ) is dependent on the metal ion involved.