Synthesis, characterization, and photobehavior of cis- and trans-diammine(1,4,8,11-tetraazacyclotetradecane)chromium(II) and some related compounds

cis-andtrans-Diisothiocyanato(1,4,8,11-tetraazacyclotetradecane)chromium(III) Perchlorate

“…The cis isomer was prepared from cis-[Cr(cyclam)Cl2]Cl using an adaptation of existing literature methods (Kane-Maguire, Wallace & Miller, 1985;Ferguson & Tobe, 1970;Friesen, 1994). The trans isomer was synthesized from trans- Miller, 1985;Friesen, 1994). The preparation and analysis of these isomers as perchlorate salts using standard procedures has been described elsewhere (Friesen, 1994).…”

Metal centered ligand field excited states: Their roles in the design and performance of transition metal based photochemical molecular devices

“…Typically, the more N-H oscillators directly bound to the metal, the shorter the phosphorescence lifetime [73,80]. For example, the 77 K lifetime of Cr(NH 3 ) 6 3+ (with 18 N-H oscillators on atoms directly coordinated to the Cr(III)) is 70 s, whereas that for trans-Cr(cyclam)(NH 3 ) 2 3+ (with only 10 N-H oscillators) is 180 s [81]. These lifetimes also respond substantially to deuteration of the am(m)ines [18,82], e.g., N-H deuteration of trans-Cr(cyclam)(NH 3 ) 2 3+ increases its 77 K lifetime to 3720 s [81].…”

Structure of cis-(1,2-ethanediamine)(1,4,8,11-tetraazacyclotetradecane)chromium(III) perchlorate

“…After recrystallization from perchloric acid solution, analysis of the yellow compound obtained showed it to be a mixture of the triperchlorate and the diperchlorate nitrate, paralleling the behaviour of hexafluorophosphate and. tetrafluoroborate salts reported earlier (Kane-Maguire, Wallace & Miller, 1985).…”

“…There are other structure reports of cis cyclam Cr nI complexes (Forsellini, Parasassi, Bombieri, Tobe & Sosa, 1986), but none of these concerns the coordination of Cr nI to six amine ligands. Such amine complexes have played an important role in photochemical and photophysical studies, and their properties are anomalous in ways that seem to relate to the angular distortions of the coordination sphere at Cr nI (Kirk & Guedel, 1992 Wallace & Miller, 1985). After recrystallization from perchloric acid solution, analysis of the yellow compound obtained showed it to be a mixture of the triperchlorate and the diperchlorate nitrate, paralleling the behaviour of hexafluorophosphate and.…”