The “masked” terminal Zn sulfide, [K(2.2.2‐cryptand)][MeLZn(S)] (
Improved complexation of paraquats with crown ether‐based pyridyl cryptands
The commonly used paraquat guest
- PAR ID:
- 10047958
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Heteroatom Chemistry
- Volume:
- 28
- Issue:
- 6
- ISSN:
- 1042-7163
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract 2 ) (MeL={(2,6‐iPr2C6H3)NC(Me)}2CH), was isolated via reaction of [MeLZnSCPh3] (1 ) with 2.3 equivalents of KC8in THF, in the presence of 2.2.2‐cryptand, at −78 °C. Complex2 reacts readily with PhCCH and N2O to form [K(2.2.2‐cryptand)][MeLZn(SH)(CCPh)] (4 ) and [K(2.2.2‐cryptand)][MeLZn(SNNO)] (5 ), respectively, displaying both Brønsted and Lewis basicity. In addition, the electronic structure of2 was examined computationally and compared with the previously reported Ni congener, [K(2.2.2‐cryptand)][tBuLNi(S)] (tBuL={(2,6‐iPr2C6H3)NC(tBu)}2CH). -
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Abstract The “masked” terminal Zn sulfide, [K(2.2.2‐cryptand)][MeLZn(S)] (
2 ) (MeL={(2,6‐iPr2C6H3)NC(Me)}2CH), was isolated via reaction of [MeLZnSCPh3] (1 ) with 2.3 equivalents of KC8in THF, in the presence of 2.2.2‐cryptand, at −78 °C. Complex2 reacts readily with PhCCH and N2O to form [K(2.2.2‐cryptand)][MeLZn(SH)(CCPh)] (4 ) and [K(2.2.2‐cryptand)][MeLZn(SNNO)] (5 ), respectively, displaying both Brønsted and Lewis basicity. In addition, the electronic structure of2 was examined computationally and compared with the previously reported Ni congener, [K(2.2.2‐cryptand)][tBuLNi(S)] (tBuL={(2,6‐iPr2C6H3)NC(tBu)}2CH). -
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Abstract A family of neodymium complexes featuring a redox‐active ligand in three different oxidation states has been synthesized, including the iminoquinone (L0) derivative, (dippiq)2NdI3(
1‐iq ), the iminosemiquinone (L1−) compound, (dippisq)2NdI(THF) (1‐isq ), and the amidophenolate (L2−) [K(THF)2][(dippap)2Nd(THF)2] (1‐ap ) and [K(18‐crown‐6)][(dippap)2Nd(THF)2] (1‐ap crown ) species. Full spectroscopic and structural characterization of each derivative established the +3 neodymium oxidation state with redox chemistry occurring at the ligand rather than the neodymium center. Oxidation with elemental chalcogens showed the reversible nature of the ligand‐mediated reduction process, forming the iminosemiquinone metallocycles, [K(18‐crown‐6)][(dippisq)2Nd(S5)] (2‐isq crown ) and [K(18‐crown‐6)(THF)][(dippisq)2Nd(Se5)] (3‐isq crown ), which are characterized to contain a 6‐membered twist‐boat ring. -
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Abstract A family of neodymium complexes featuring a redox‐active ligand in three different oxidation states has been synthesized, including the iminoquinone (L0) derivative, (dippiq)2NdI3(
1‐iq ), the iminosemiquinone (L1−) compound, (dippisq)2NdI(THF) (1‐isq ), and the amidophenolate (L2−) [K(THF)2][(dippap)2Nd(THF)2] (1‐ap ) and [K(18‐crown‐6)][(dippap)2Nd(THF)2] (1‐ap crown ) species. Full spectroscopic and structural characterization of each derivative established the +3 neodymium oxidation state with redox chemistry occurring at the ligand rather than the neodymium center. Oxidation with elemental chalcogens showed the reversible nature of the ligand‐mediated reduction process, forming the iminosemiquinone metallocycles, [K(18‐crown‐6)][(dippisq)2Nd(S5)] (2‐isq crown ) and [K(18‐crown‐6)(THF)][(dippisq)2Nd(Se5)] (3‐isq crown ), which are characterized to contain a 6‐membered twist‐boat ring. -
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Abstract Two new cryptands,
2 and4 , were prepared from bis(m ‐phenylene)‐32‐crown‐10 (BMP32) 5,5'‐diacid chloride and dibenzo‐30‐crown‐10 (DB30) 4,4'‐diacid chloride, respectively, by reaction with pyridine‐2,6‐dimethanol. The resultant cryptands2 and4 have the ester moieties reversed from the previously reported isomers,1 and3 . These “reverse” cryptands display lower association constants with viologen derivatives than the original cryptands; this is rationalized by the conjugation of the ester moieties with the aromatic rings, which reduces their electron‐donating properties and offsets the increased basicity of the pyridyl nitrogen atoms. The crystal structure of the BMP32‐based cryptand2 indeed confirms the coplanarity of the ester and aromatic moieties and indicates that, as a result, the available cavity is quite small and that the pyridyl nitrogen atom points away from the cavity.
