Mono- and dinuclear nickel(ii) complexes of resolved Schiff-base ligands with extended quinoline substituents

Dipesh Prema, Kayode Oshin, John Desper, Christopher J. Levy

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The coordination chemistry of four enantiopure tetradentate bis(iminoquinoline) ligands with nickel(ii) salts is reported. The previously reported ligands CBQ, CPQ, BBQ, and BPQ result from the condensation of (1R,2R)-cyclohexyldiamine or (R)-BINAM with two equivalents of 2-formylbenzo[h]quinoline or 8-isopropyl-2-quinolinecarboxaldehyde {CBQ = (1R,2R)-cyclohexanediamine-N,N′-bis(benzo[h]quinoline-2-ylmethylene), CPQ = (1R,2R)-cyclohexanediamine-N,N′-bis[[(8-isopropyl)-2-quinolinyl] methylene], BBQ = [(R)-1,1′-binaphthalene]-2,2′-diamine-N,N′- bis(benzo[h]quinoline-2-ylmethylene), BPQ = [(R)-1,1′-binaphthalene]-2, 2′-diamine-N,N′-bis[[(8-isopropyl)-2-quinolinyl]methylene]}. Reaction of NiI 2 with the (1R,2R)-cyclohexyl ligands gives the mononuclear distorted trigonal-bipyramidal (TBP) complexes [Ni(N 3-CBQ)I 2] and [Ni(N 3-CPQ)I 2]. Incomplete iodide abstraction from [Ni(N 3-CPQ)I 2] with AgOTf leads to partial replacement of the iodide with hydroxide from adventitious water to give [Ni(N 3-CPQ)I 1.6(OH) 0.4] (distorted TBP). The corresponding reaction with [Ni(N 3-CBQ)I 2] again fails to remove all of the iodide, resulting instead in conversion to the syn dinuclear [Ni 2(CBQ)(μ- X) 2I 2] (X = Cl 0.925I 0.075) complex, where chloride abstraction from the solvent (CH 2Cl 2) has resulted in a mixed halide system and the metal centers are square-pyramidal. Reaction of Ni(OTf) 2 with CBQ leads to the isolation of the octahedral cation [Ni(CMBQ) 2] 2+, with CMBQ [(1R,2R)-cyclohexanediamine-mono-N-(benzo[h]quinoline-2-ylmethylene)] being the partial hydrolysis product of CBQ. [Ni(CMBQ) 2][OTf] 2 crystallizes as a 1:1 mixture of P and M helical diastereomers. The coordination of NiI 2 with the (R)-BINAM derived ligands yields the anti dinuclear P-helical complexes [Ni 2(BBQ)(μ-I) 2I 2] and [Ni 2(BPQ)(μ-I) 2I 2]: one nickel ion is coordinated in each bidentate iminoquinoline pocket and the geometry at the metal centers is distorted square-pyramidal. Characterisation by 1H NMR, UV-Vis, electronic circular dichroism (ECD) spectroscopy, combustion analysis, and HRMS is reported in addition to structural and halide abstraction studies.

Original languageEnglish (US)
Pages (from-to)4998-5009
Number of pages12
JournalDalton Transactions
Volume41
Issue number16
DOIs
StatePublished - Apr 28 2012
Externally publishedYes

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Schiff Bases
Nickel
Iodides
Ligands
Diamines
Metals
Circular dichroism spectroscopy
Cations
Chlorides
Condensation
Hydrolysis
Salts
Nuclear magnetic resonance
Ions
Geometry
quinoline
Water
benzo(h)quinoline

All Science Journal Classification (ASJC) codes

  • Inorganic Chemistry

Cite this

Mono- and dinuclear nickel(ii) complexes of resolved Schiff-base ligands with extended quinoline substituents. / Prema, Dipesh; Oshin, Kayode; Desper, John; Levy, Christopher J.

In: Dalton Transactions, Vol. 41, No. 16, 28.04.2012, p. 4998-5009.

Research output: Contribution to journalArticle

Prema, Dipesh ; Oshin, Kayode ; Desper, John ; Levy, Christopher J. / Mono- and dinuclear nickel(ii) complexes of resolved Schiff-base ligands with extended quinoline substituents. In: Dalton Transactions. 2012 ; Vol. 41, No. 16. pp. 4998-5009.
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title = "Mono- and dinuclear nickel(ii) complexes of resolved Schiff-base ligands with extended quinoline substituents",
abstract = "The coordination chemistry of four enantiopure tetradentate bis(iminoquinoline) ligands with nickel(ii) salts is reported. The previously reported ligands CBQ, CPQ, BBQ, and BPQ result from the condensation of (1R,2R)-cyclohexyldiamine or (R)-BINAM with two equivalents of 2-formylbenzo[h]quinoline or 8-isopropyl-2-quinolinecarboxaldehyde {CBQ = (1R,2R)-cyclohexanediamine-N,N′-bis(benzo[h]quinoline-2-ylmethylene), CPQ = (1R,2R)-cyclohexanediamine-N,N′-bis[[(8-isopropyl)-2-quinolinyl] methylene], BBQ = [(R)-1,1′-binaphthalene]-2,2′-diamine-N,N′- bis(benzo[h]quinoline-2-ylmethylene), BPQ = [(R)-1,1′-binaphthalene]-2, 2′-diamine-N,N′-bis[[(8-isopropyl)-2-quinolinyl]methylene]}. Reaction of NiI 2 with the (1R,2R)-cyclohexyl ligands gives the mononuclear distorted trigonal-bipyramidal (TBP) complexes [Ni(N 3-CBQ)I 2] and [Ni(N 3-CPQ)I 2]. Incomplete iodide abstraction from [Ni(N 3-CPQ)I 2] with AgOTf leads to partial replacement of the iodide with hydroxide from adventitious water to give [Ni(N 3-CPQ)I 1.6(OH) 0.4] (distorted TBP). The corresponding reaction with [Ni(N 3-CBQ)I 2] again fails to remove all of the iodide, resulting instead in conversion to the syn dinuclear [Ni 2(CBQ)(μ- X) 2I 2] (X = Cl 0.925I 0.075) complex, where chloride abstraction from the solvent (CH 2Cl 2) has resulted in a mixed halide system and the metal centers are square-pyramidal. Reaction of Ni(OTf) 2 with CBQ leads to the isolation of the octahedral cation [Ni(CMBQ) 2] 2+, with CMBQ [(1R,2R)-cyclohexanediamine-mono-N-(benzo[h]quinoline-2-ylmethylene)] being the partial hydrolysis product of CBQ. [Ni(CMBQ) 2][OTf] 2 crystallizes as a 1:1 mixture of P and M helical diastereomers. The coordination of NiI 2 with the (R)-BINAM derived ligands yields the anti dinuclear P-helical complexes [Ni 2(BBQ)(μ-I) 2I 2] and [Ni 2(BPQ)(μ-I) 2I 2]: one nickel ion is coordinated in each bidentate iminoquinoline pocket and the geometry at the metal centers is distorted square-pyramidal. Characterisation by 1H NMR, UV-Vis, electronic circular dichroism (ECD) spectroscopy, combustion analysis, and HRMS is reported in addition to structural and halide abstraction studies.",
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T1 - Mono- and dinuclear nickel(ii) complexes of resolved Schiff-base ligands with extended quinoline substituents

AU - Prema, Dipesh

AU - Oshin, Kayode

AU - Desper, John

AU - Levy, Christopher J.

PY - 2012/4/28

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N2 - The coordination chemistry of four enantiopure tetradentate bis(iminoquinoline) ligands with nickel(ii) salts is reported. The previously reported ligands CBQ, CPQ, BBQ, and BPQ result from the condensation of (1R,2R)-cyclohexyldiamine or (R)-BINAM with two equivalents of 2-formylbenzo[h]quinoline or 8-isopropyl-2-quinolinecarboxaldehyde {CBQ = (1R,2R)-cyclohexanediamine-N,N′-bis(benzo[h]quinoline-2-ylmethylene), CPQ = (1R,2R)-cyclohexanediamine-N,N′-bis[[(8-isopropyl)-2-quinolinyl] methylene], BBQ = [(R)-1,1′-binaphthalene]-2,2′-diamine-N,N′- bis(benzo[h]quinoline-2-ylmethylene), BPQ = [(R)-1,1′-binaphthalene]-2, 2′-diamine-N,N′-bis[[(8-isopropyl)-2-quinolinyl]methylene]}. Reaction of NiI 2 with the (1R,2R)-cyclohexyl ligands gives the mononuclear distorted trigonal-bipyramidal (TBP) complexes [Ni(N 3-CBQ)I 2] and [Ni(N 3-CPQ)I 2]. Incomplete iodide abstraction from [Ni(N 3-CPQ)I 2] with AgOTf leads to partial replacement of the iodide with hydroxide from adventitious water to give [Ni(N 3-CPQ)I 1.6(OH) 0.4] (distorted TBP). The corresponding reaction with [Ni(N 3-CBQ)I 2] again fails to remove all of the iodide, resulting instead in conversion to the syn dinuclear [Ni 2(CBQ)(μ- X) 2I 2] (X = Cl 0.925I 0.075) complex, where chloride abstraction from the solvent (CH 2Cl 2) has resulted in a mixed halide system and the metal centers are square-pyramidal. Reaction of Ni(OTf) 2 with CBQ leads to the isolation of the octahedral cation [Ni(CMBQ) 2] 2+, with CMBQ [(1R,2R)-cyclohexanediamine-mono-N-(benzo[h]quinoline-2-ylmethylene)] being the partial hydrolysis product of CBQ. [Ni(CMBQ) 2][OTf] 2 crystallizes as a 1:1 mixture of P and M helical diastereomers. The coordination of NiI 2 with the (R)-BINAM derived ligands yields the anti dinuclear P-helical complexes [Ni 2(BBQ)(μ-I) 2I 2] and [Ni 2(BPQ)(μ-I) 2I 2]: one nickel ion is coordinated in each bidentate iminoquinoline pocket and the geometry at the metal centers is distorted square-pyramidal. Characterisation by 1H NMR, UV-Vis, electronic circular dichroism (ECD) spectroscopy, combustion analysis, and HRMS is reported in addition to structural and halide abstraction studies.

AB - The coordination chemistry of four enantiopure tetradentate bis(iminoquinoline) ligands with nickel(ii) salts is reported. The previously reported ligands CBQ, CPQ, BBQ, and BPQ result from the condensation of (1R,2R)-cyclohexyldiamine or (R)-BINAM with two equivalents of 2-formylbenzo[h]quinoline or 8-isopropyl-2-quinolinecarboxaldehyde {CBQ = (1R,2R)-cyclohexanediamine-N,N′-bis(benzo[h]quinoline-2-ylmethylene), CPQ = (1R,2R)-cyclohexanediamine-N,N′-bis[[(8-isopropyl)-2-quinolinyl] methylene], BBQ = [(R)-1,1′-binaphthalene]-2,2′-diamine-N,N′- bis(benzo[h]quinoline-2-ylmethylene), BPQ = [(R)-1,1′-binaphthalene]-2, 2′-diamine-N,N′-bis[[(8-isopropyl)-2-quinolinyl]methylene]}. Reaction of NiI 2 with the (1R,2R)-cyclohexyl ligands gives the mononuclear distorted trigonal-bipyramidal (TBP) complexes [Ni(N 3-CBQ)I 2] and [Ni(N 3-CPQ)I 2]. Incomplete iodide abstraction from [Ni(N 3-CPQ)I 2] with AgOTf leads to partial replacement of the iodide with hydroxide from adventitious water to give [Ni(N 3-CPQ)I 1.6(OH) 0.4] (distorted TBP). The corresponding reaction with [Ni(N 3-CBQ)I 2] again fails to remove all of the iodide, resulting instead in conversion to the syn dinuclear [Ni 2(CBQ)(μ- X) 2I 2] (X = Cl 0.925I 0.075) complex, where chloride abstraction from the solvent (CH 2Cl 2) has resulted in a mixed halide system and the metal centers are square-pyramidal. Reaction of Ni(OTf) 2 with CBQ leads to the isolation of the octahedral cation [Ni(CMBQ) 2] 2+, with CMBQ [(1R,2R)-cyclohexanediamine-mono-N-(benzo[h]quinoline-2-ylmethylene)] being the partial hydrolysis product of CBQ. [Ni(CMBQ) 2][OTf] 2 crystallizes as a 1:1 mixture of P and M helical diastereomers. The coordination of NiI 2 with the (R)-BINAM derived ligands yields the anti dinuclear P-helical complexes [Ni 2(BBQ)(μ-I) 2I 2] and [Ni 2(BPQ)(μ-I) 2I 2]: one nickel ion is coordinated in each bidentate iminoquinoline pocket and the geometry at the metal centers is distorted square-pyramidal. Characterisation by 1H NMR, UV-Vis, electronic circular dichroism (ECD) spectroscopy, combustion analysis, and HRMS is reported in addition to structural and halide abstraction studies.

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