The crystal structure of (+)589-cis-β-carbonato-(3S,8S-dimethyltriethylenetetramine)cobalt(III) perchlorate

Abstract

[Co(CO3) (3,8-dimetrien)]CIO4 crystallizes in the space group P2~2~2,, with four formula units in a cell of dimensions a= 12"284 (2), b= 17"913 (8) and c= 7.179 (3) A. The structure was solved by the heavyatom method and the positional and thermal parameters were refined by the method of least squares, using anisotropic thermal factors for the non-hydrogen atoms. The final R value for the 1894 observed reflexions collected by diffractometry is 0.041. The quadridentate ligand is linked to the central metal atom in cis-fl coordination. One of the substituted methyl groups lies in an equatorial position with respect to the chelate ring, while the other is in an axial position. All the bond lengths are normal. The Co-N distances range from 1"935 (5) to 1"958 (5) A. The absolute configuration of the complex ion can be designated as A(622). The absolute configurations about the two secondary nitrogen atoms are both R.

Carbonato[tris(2-aminoethyl)amine]cobalt(III) chloride trihydrate, [Co(C6H18N4)(CO3)]Cl.3H2O

“…The terminal nitrogen which is trans to the other carbonate oxygen also has a short Co-N distance [1.929 (1)./k]. A similar effect was observed by Toriumi & Saito (1975) …”

Absolute structure of (–)546-cis-β-carbonato(triethylenetetramine)cobalt(III) perchlorate monohydrate

“…The atom groupings O(1), 0(2), C(7), 0(3) and O(1), O(2), Co, N(1), N(3) are planar, the maximum deviations being 0.001(3) and -0.027 (2)/~ respectively. The dihedral angle between the planes of 1.1 ° is less than that found in some other cobalt carbonate compounds (Toriumi & Saito, 1975;Geue & Snow, 1971;Hoskins & Urban, 1987). Within the perchlorate group the average C1--O distance is 1.41 (3)/~.…”

“…It has been argued that the shortened bond reduces angular strain at the secondary N atom (Buckingham, Cresswell, Dellaca, Dwyer, Gainsford, Marzilli, Maxwell, Robinson, Sargeson & Turnbull, 1974). In cases where the chelating carbonate group is present it has been suggested that the shortened bond may result from a trans influence of the carbonate ion (Schlemper, Sen Gupta & Desgupta, 1983;Toriumi & Saito, 1975). Since the structure under investigation contains a carbonate group, it seems reasonable to suggest that both factors are at play.…”