A new series of mono‐ and bis‐alkynyl CoIII(TIM) complexes (TIM=2,3,9,10‐tetramethyl‐1,4,8,11‐tetraazacyclotetradeca‐1,3,8,10‐tetraene) is reported herein. The
The syntheses of the 2,9‐dimesityl‐1,10‐phenanthroline (
- NSF-PAR ID:
- 10457482
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Polymer Science
- Volume:
- 58
- Issue:
- 8
- ISSN:
- 2642-4150
- Page Range / eLocation ID:
- p. 1130-1143
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract trans ‐[Co(TIM)(C2R)Cl]+complexes were prepared from the reaction betweentrans ‐[Co(TIM)Cl2]PF6and HC2R (R=tri(isopropyl)silyl or TIPS (1 ), ‐C6H4‐4‐tBu (2 ), ‐C6H4‐4‐NO2(3 a ), andN ‐mesityl‐1,8‐naphthalimide or NAPMes(4 a )) in the presence of Et3N. The intermediate complexes of the typetrans ‐[Co(TIM)(C2R)(NCMe)](PF6)(OTf),3 b and4 b , were obtained by treating3 a and4 a , respectively, with AgOTf in CH3CN. Furthermore, bis‐alkynyltrans ‐[Co(TIM)(C2R)2]PF6complexes,3 c and4 c , were generated following a second dehydrohalogenation reaction between3 b and4 b , respectively, and the appropriate HC2R in the presence of Et3N. These new complexes have been characterized using X‐ray diffraction (2 ,3 a ,4 a , and4 c ), IR,1H NMR, UV/Vis spectroscopy, fluorescent spectroscopy (4 c ), and cyclic voltammetry. -
Abstract Three binuclear species [LCoIII2(μ‐Pz)2](ClO4)3(
1 ), [LNiII2(CH3OH)2Cl2]ClO4(2 ), and [LZnII2Cl2]PF6(3 ) supported by the deprotonated form of the ligand 2,6‐bis[bis(2‐pyridylmethyl) amino‐methyl]‐4‐methylphenol were synthesized, structurally characterized as solids and in solution, and had their electrochemical and spectroscopic behavior established. Species1 –3 had their water reduction ability studied aiming to interrogate the possible cooperative catalytic activity between two neighboring metal centers. Species1 and2 reduced H2O to H2effectively at an applied potential of −1.6 VAg/AgCl, yielding turnover numbers of 2,820 and 2,290, respectively, after 30 minutes. Species3 lacked activity and was used as a negative control to eliminate the possibility of ligand‐based catalysis. Pre‐ and post‐catalytic data gave evidence of the molecular nature of the process within the timeframe of the experiments. Species1 showed structural, rather than electronic cooperativity, while species2 displayed no obvious cooperativity. DFT methods complemented the experimental results determining plausible mechanisms. -
Abstract Exploration of the reduction chemistry of the 2,2’‐bipyridine (bipy) lanthanide metallocene complexes Cp*2LnCl(bipy) and Cp*2Ln(bipy) (Cp* = C5Me5) resulted in the isolation of a series of complexes with unusual composition and structure including complexes with a single Cp* ligand, multiple azide ligands, and bipy ligands with close parallel orientations. These results not only reveal new structural types, but they also show the diverse chemistry displayed by this redox‐active platform. Treatment of Cp*2NdCl(bipy) with excess KC8resulted in the formation of the mono‐Cp* Nd(III) complex, [K(crypt)]2[Cp*Nd(bipy)2],
1 , as well as [K(crypt)][Cp*2NdCl2],2 , and the previously reported [K(crypt)][Cp*2Nd(bipy)]. A mono‐Cp* Lu(III) complex, Cp*Lu(bipy)2,3 , was also found in an attempt to make Cp*2Lu(bipy) from LuCl3, 2 equiv. of KCp*, bipy, and K/KI. Surprisingly, the (bipy)1−ligands in neighboring molecules in the structure of3 are oriented in a parallel fashion with intermolecular C⋅⋅⋅C distances of 3.289(4) Å, which are shorter than the sum of van der Waals radii of two carbon atoms, 3.4 Å. Another product with one Cp* ligand per lanthanide was isolated from the reaction of [K(crypt)][Cp*2Eu(bipy)] with azobenzene, which afforded the dimeric Eu(II) complex, [K(crypt)]2[Cp*Eu(THF)(PhNNPh)]2,4 . Attempts to make4 from the reaction between Cp*2Eu(THF)2and a reduced azobenzene anion generated instead the mixed‐valent Eu(III)/Eu(II) complex, [K(crypt)][Cp*Eu(THF)(PhNNPh)]2,5 , which allows direct comparison with the bimetallic Eu(II) complex4 . Mono‐Cp* complexes of Yb(III) are obtained from reactions of the Yb(II) complex, [K(crypt)][Cp*2Yb(bipy)], with trimethylsilylazide, which afforded the tetra‐azido [K(crypt)]2[Cp*Yb(N3)4],6 , or the di‐azido complex [K(crypt)]2[Cp*Yb(N3)2(bipy)],7 a , depending on the reaction stoichiometry. A mono‐Cp* Yb(III) complex is also isolated from reaction of [K(crypt)][Cp*2Yb(bipy)] with elemental sulfur which forms the mixed polysulfido Yb(III) complex [K(crypt)]2[Cp*Yb(S4)(S5)],8 a . In contrast to these reactions that form mono‐Cp* products, reduction of Cp*2Yb(bipy) with 1 equiv. of KC8in the presence of 18‐crown‐6 resulted in the complete loss of Cp* ligands and the formation of [K(18‐c‐6)(THF)][Yb(bipy)4],9 . The (bipy)1−ligands of9 are arranged in a parallel orientation, as observed in the structure of3 , except in this case this interaction is intramolecular and involves pairs of ligands bound to the same Yb atom. Attempts to reduce further the Sm(II) (bipy)1−complex, Cp*2Sm(bipy) with 2 equiv. of KC8in the presence of excess 18‐crown‐6 led to the isolation of a Sm(III) salt of (bipy)2−with an inverse sandwich Cp* counter‐cation and a co‐crystallized K(18‐c‐6)Cp* unit, [K2(18‐c‐6)2Cp*]2[Cp*2Sm(bipy)]2 ⋅ [K(18‐c‐6)Cp*],10 . -
Abstract Metalation of the polynucleating ligandF,tbsLH6(1,3,5‐C6H9(NC6H3−4‐F−2‐NSiMe2tBu)3) with two equivalents of Zn(N(SiMe3)2)2affords the dinuclear product (F,tbsLH2)Zn2(
1 ), which can be further deprotonated to yield (F,tbsL)Zn2Li2(OEt2)4(2 ). Transmetalation of2 with NiCl2(py)2yields the heterometallic, trinuclear cluster (F,tbsL)Zn2Ni(py) (3 ). Reduction of3 with KC8affords [KC222][(F,tbsL)Zn2Ni] (4 ) which features a monovalent Ni centre. Addition of 1‐adamantyl azide to4 generates the bridging μ3‐nitrenoid adduct [K(THF)3][(F,tbsL)Zn2Ni(μ3‐NAd)] (5 ). EPR spectroscopy reveals that the anionic cluster possesses a doublet ground state (S =). Cyclic voltammetry of 5 reveals two fully reversible redox events. The dianionic nitrenoid [K2(THF)9][(F,tbsL)Zn2Ni(μ3‐NAd)] (6 ) was isolated and characterized while the neutral redox isomer was observed to undergo both intra‐ and intermolecular H‐atom abstraction processes. Ni K‐edge XAS studies suggest a divalent oxidation state for the Ni centres in both the monoanionic and dianionic [Zn2Ni] nitrenoid complexes. However, DFT analysis suggests Ni‐borne oxidation for5 . -
Abstract Metalation of the polynucleating ligandF,tbsLH6(1,3,5‐C6H9(NC6H3−4‐F−2‐NSiMe2tBu)3) with two equivalents of Zn(N(SiMe3)2)2affords the dinuclear product (F,tbsLH2)Zn2(
1 ), which can be further deprotonated to yield (F,tbsL)Zn2Li2(OEt2)4(2 ). Transmetalation of2 with NiCl2(py)2yields the heterometallic, trinuclear cluster (F,tbsL)Zn2Ni(py) (3 ). Reduction of3 with KC8affords [KC222][(F,tbsL)Zn2Ni] (4 ) which features a monovalent Ni centre. Addition of 1‐adamantyl azide to4 generates the bridging μ3‐nitrenoid adduct [K(THF)3][(F,tbsL)Zn2Ni(μ3‐NAd)] (5 ). EPR spectroscopy reveals that the anionic cluster possesses a doublet ground state (S =). Cyclic voltammetry of 5 reveals two fully reversible redox events. The dianionic nitrenoid [K2(THF)9][(F,tbsL)Zn2Ni(μ3‐NAd)] (6 ) was isolated and characterized while the neutral redox isomer was observed to undergo both intra‐ and intermolecular H‐atom abstraction processes. Ni K‐edge XAS studies suggest a divalent oxidation state for the Ni centres in both the monoanionic and dianionic [Zn2Ni] nitrenoid complexes. However, DFT analysis suggests Ni‐borne oxidation for5 .