The Crystal Structure of (−)D-Tris(trimethylenediamine)cobalt(III) Bromide Monohydrate

Abstract

The structure of (−)D-[Co(tn)3]Br3·H2O (tn: H2N–CH2-CH2-CH2-NH2) has been solved by the heavy atom method and refined to R=0.11 by least-squares analysis based on 1845 threedimensional data. The substance crystallizes in the monoclinic space group P21 with unit cell dimensions: a=16.274, b=9.863, c=9.489 Å, β=126.4° and Z=2. The complex ion in the structure has approximately a three-fold axis of rotation. The three six-membered Co-tn rings are nearly identical and take chair form. The chelate ring is rather flattened out, owing to the strong H-H repulsion. The absolute configuration of (−)D-[Co(tn)3]3+ has been found to be the same as that of (+)D-[Co(en)3]3+.

The crystal structure of (−)589-tris(1,3-diaminopropane)cobalt(III) chloride monohydrate, (−)589-[Co(tn)3]Cl3.H2O

“…Table 3 lists some of the observed relations between hkl and hki and the calculated values. Comparison of the observed and calculated differences shows that the complex ion has the absolute configuration A, in accordance with our previous results (Nomura et al, 1969).…”

The crystal structure of (+)546-tris(R,R-2,4-diaminopentane)cobalt(III) chloride monohydrate, (+)456-[Co(R,R-ptn)3]Cl3.H2O

“…The sixmembered chelate ring has a twisted-boat form. The NCoN angles, unlike those in the (-)589-tris(1,3- (Nomura, Marumo & Saito, 1969), are all less than 90 °, the average being 87.9 + 1.3 °. The distortion of an octahedron formed by the six nitrogen atoms is opposite to that observed in A-[Co(tn)a] a+.…”

The crystal structure of (−)589-tris[(+)-trans-1,2-diaminocyclohexane]cobalt(III) chloride pentahydrate, (−)589-{Co[(+)-chxn]3}Cl3.5H2O

“…These values are quite normal in tris(diamine) cobalt(Ill) complexes, e.g. (+)589 [Co(en)3]C13.H20 (Iwata, Nakatsu & Saito, 1969), (-)589 [Co(-pn)3]Br~ (lwasaki & Saito, 1966) and (-)589 [Co(tn)3]Br3.H20 (Nomura, Marumo & Saito, 1969). The C-C and C-N distances are in agreement with the single-bond distances within experimental error.…”