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  1. Abstract

    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. Thetrans‐[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 band4 b, were obtained by treating3 aand4 a, respectively, with AgOTf in CH3CN. Furthermore, bis‐alkynyltrans‐[Co(TIM)(C2R)2]PF6complexes,3 cand4 c, were generated following a second dehydrohalogenation reaction between3 band4 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.

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  2. Abstract

    A pair of novel Fe‐alkynyl complexes, [FeIII(HMTI)(C2SiEt3)2]ClO4(2) and [FeII(HMTI)(C2SiEt3)(NCCH3)]ClO4(3), is described herein. Reaction of Fe(meso‐HMC)Cl(ClO4)]ClO4(1) with lithiated triethylsilylacetylene and subsequent exposure to oxygen yielded the bis‐alkynyl2containing the dehydrogenated tetraimine macrocycle (HMTI). Reduction of2by mossy zinc in acetonitrile yielded the mono‐alkynyl3. The structures of2and3were determined using single‐crystal X‐ray diffraction. Analysis of visible absorption and electrochemical data establishes the redox‐active nature of the HMTI macrocycle, and indicates significant interactions between the Fedπ and tetraimine π* orbitals. These deductions are further supported by density functional theory calculations.

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  3. Free, publicly-accessible full text available October 1, 2024
  4. Both trans and cis iron–CTMC complexes, namely, trans -dichlorido[(5 SR ,7 RS ,12 RS ,14 SR )-5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradecane]iron(III) tetrachloridoferrate, [Fe(C 14 H 32 N 4 )Cl 2 ][FeCl 4 ] ( 1a ), the analogous chloride methanol monosolvate, [Fe(C 14 H 32 N 4 )Cl 2 ]Cl·CH 3 OH ( 1b ), and cis -dichlorido[(5 SR ,7 RS ,12 SR ,14 RS )-5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradecane]iron(III) chloride, [Fe(C 14 H 32 N 4 )Cl 2 ]Cl ( 2 ), were successfully synthesized and structurally characterized using X-ray diffraction. The coordination geometry of the macrocycle is dependent on the stereoisomerism of CTMC. The packing of these complexes appears to be strongly influenced by extensive hydrogen-bonding interactions, which are in turn determined by the nature of the counter-anions ( 1a versus 1b ) and/or the coordination geometry of the macrocycle ( 1a/1b versus 2 ). These observations are extended to related ferric cis - and trans- dichloro macrocyclic complexes. 
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  5. The new compound [(NC)Ru 2 (ap) 4 ] 2 (μ-1,4-C 6 H 4 ) (ap = 2-anilinopyridinate) was prepared to address the open question of whether a 1,4-phenylene bridge can mediate intermetallic electronic coupling. As a manifestation of strong coupling, hole delocalization between the Ru 2 centers on the IR time scale (10 −14 s) was established using spectroelectrochemistry. An orbital mechanism for coupling was elaborated with DFT analysis. 
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  6. Reported herein are the two new series of diruthenium aryl compounds: Ru 2 (DiMeOap) 4 (Ar) (1a–6a) (DiMeOap = 2-(3,5-dimethoxyanilino)pyridinate) and Ru 2 ( m - i PrOap) 4 (Ar) (1b–5b) ( m - i PrOap = 2-(3-iso-propoxyanilino)pyridinate), prepared through the lithium-halogen exchange reaction with a variety of aryl halides (Ar = C 6 H 4 -4-NMe 2 (1), C 6 H 4 -4- t Bu (2), C 6 H 4 -4-OMe (3), C 6 H 3 -3,5-(OMe) 2 (4), C 6 H 4 -4-CF 3 (5), C 6 H 5 (6)). The molecular structures of these compounds were established with X-ray diffraction studies. Additionally, these compounds were characterized using electronic absorption and voltammetric techniques. Compounds 1a–6a and 1b–5b are all in the Ru 2 5+ oxidation state, with a ground state configuration of σ 2 π 4 δ 2 (π*δ*) 3 ( S = 3/2). Use of the modified ap ligands (ap′) resulted in moderate increases of product yield when compared to the unsubstituted Ru 2 (ap) 4 (Ar) (ap = 2-anilinopyridinate) series. Comparisons of the electrochemical properties of 1a–6a and 1b–5b against the Ru 2 (ap′)Cl starting material reveals the addition of the aryl ligand cathodically shifted the Ru 2 6+/5+ oxidation and Ru 2 5+/4+ reduction potentials. These oxidation and reductions potentials are also strongly dependent on the p -substituent of the axial aryl ligands. 
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