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 language | English (US) |
|---|---|
| Pages (from-to) | 4998-5009 |
| Number of pages | 12 |
| Journal | Dalton Transactions |
| Volume | 41 |
| Issue number | 16 |
| DOIs | |
| State | Published - Apr 28 2012 |
| Externally published | Yes |
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All Science Journal Classification (ASJC) codes
- Inorganic Chemistry
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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 journal › Article
}
TY - JOUR
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
Y1 - 2012/4/28
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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U2 - 10.1039/c2dt11813k
DO - 10.1039/c2dt11813k
M3 - Article
VL - 41
SP - 4998
EP - 5009
JO - Dalton Transactions
JF - Dalton Transactions
SN - 1477-9226
IS - 16
ER -