Synthesis, characterization and structure of cis and trans cobalt(III) bis chelates of 2-methyl-1,3-propanediamine, a prochiral sinambic ligand
1983; Elsevier BV; Volume: 73; Linguagem: Inglês
10.1016/s0020-1693(00)90857-0
ISSN1873-3255
AutoresJ D. Mather, Robert E. Tapscott, Charles F. Campana,
Tópico(s)Porphyrin and Phthalocyanine Chemistry
ResumoCis and trans isomers of [Co(metn)2Cl2]+ (metn = 2-methyl-1,3-propanediamine) have been prepared and characterized. Owing to the presence of rotationally nonequivalent donor atoms in the prochiral ligand, three diastereomers are possible for the cis isomer (C2(anti), C2(syn), and C1) and two diastereomers are possible for the trans complex (C2h and C2ν). A crystal structure of the purple compound [Co(metn)2Cl2]Cl·14CH3OH shows the presence of both the cis C2(anti) and trans C2h isomers. An uncompleted structure determination on green [Co(metn)2Cl2](H3O)Cl2 ·H2O reveals only the trans C2h isomer. X-Ray crystallography also shows a flattening of the 6-membered metn chelate ring compared with that of 1,3-propanediamine. Though 13C NMR spectra of trans-[Co(metn)2Cl2]+ show no evidence for more than one isomer in solution, this may be due to undetectably small chemical shift differences between the two diastereomers possible. IR spectra indicate a solid state cis to trans rearrangement of [Co(metn)2Cl2]+ in the presence of KBr.
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