Search for: All records

Abstract A new series of mono‐ and bis‐alkynyl Co^III(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 NAP^Mes(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. 

Abstract A pair of novel Fe‐alkynyl complexes, [Fe^III(HMTI)(C₂SiEt₃)₂]ClO₄(2) and [Fe^II(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. 

Controlling electron transfer (ET) processes in donor–bridge–acceptor (DBA) compounds by mid-IR excitation can enhance our understanding of the ET dynamics and may find practical applications in molecular sensing and molecular-scale electronics. 

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.