TY - JOUR
T1 - Syntheses and crystal structures of geometrical isomeric pairs
T2 - Trans- and cis-(PPh4) [Co(acac)2(CN)2] and trans- and cis-[Co(acac)2(PMe3 or PEt3)2]PF6 (acac = pentane-2,4-dionate)
AU - Suzuki, Takayoshi
AU - Kashiwabara, Kazuo
AU - Kita, Masakazu
AU - Fujita, Junnosuke
AU - Kaizaki, Sumio
PY - 1998/10/30
Y1 - 1998/10/30
N2 - Reactions of trans-[Co(acac)2(PPh3)2]PF6 (acac = pentane-2,4-dionate) with NaCN and with PR3 (R = Me or Et) in methanol afforded new complexes, trans-(PPh4) [Co(acac)2(CN)2] and trans-[Co(acac)2(PR3)2]PF6, respectively. The structures of the new trans-isomers, together with those of the corresponding known cis-isomers, were determined by single-crystal X-ray diffraction. Complexes trans[Co(acac)2(PR3)2]+ were stable in dry organic solvents, but in wet methanol easily hydrolysed to give trans-[Co(acac)2(PR3) (H2O)] + and isomerized to cis-[Co(acac)2(PR3)2]+ by the addition of a catalytic amount of active charcoal. In contrast, trans- and cis-[Co(acac)2(CN)2]- and cis-[Co(acac)2(PR3)2]+ were stable in both dry and wet solvents. The X-ray structure analyses showed that the Co-C and Co-P bonds in the trans-isomers were longer by about 0.07 and 0.08 Å, respectively, than those of the corresponding cis-isomers. The Co-O bonds trans to cyanide and phosphine ligands were also longer than those of the mutually trans Co-O bonds, owing to the strong trans influences of cyanide and phosphine ligands.
AB - Reactions of trans-[Co(acac)2(PPh3)2]PF6 (acac = pentane-2,4-dionate) with NaCN and with PR3 (R = Me or Et) in methanol afforded new complexes, trans-(PPh4) [Co(acac)2(CN)2] and trans-[Co(acac)2(PR3)2]PF6, respectively. The structures of the new trans-isomers, together with those of the corresponding known cis-isomers, were determined by single-crystal X-ray diffraction. Complexes trans[Co(acac)2(PR3)2]+ were stable in dry organic solvents, but in wet methanol easily hydrolysed to give trans-[Co(acac)2(PR3) (H2O)] + and isomerized to cis-[Co(acac)2(PR3)2]+ by the addition of a catalytic amount of active charcoal. In contrast, trans- and cis-[Co(acac)2(CN)2]- and cis-[Co(acac)2(PR3)2]+ were stable in both dry and wet solvents. The X-ray structure analyses showed that the Co-C and Co-P bonds in the trans-isomers were longer by about 0.07 and 0.08 Å, respectively, than those of the corresponding cis-isomers. The Co-O bonds trans to cyanide and phosphine ligands were also longer than those of the mutually trans Co-O bonds, owing to the strong trans influences of cyanide and phosphine ligands.
KW - Cobalt complexes
KW - Crystal structures
KW - Cyanide complexes
KW - Phosphine complexes
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U2 - 10.1016/S0020-1693(98)00146-7
DO - 10.1016/S0020-1693(98)00146-7
M3 - Article
AN - SCOPUS:0002670738
SN - 0020-1693
VL - 281
SP - 77
EP - 84
JO - Inorganica Chimica Acta
JF - Inorganica Chimica Acta
IS - 1
ER -