
TY  - JOUR
A1  - Bernhardt, PV 
A1  - Hambley, TW 
A1  - Lawrance, GA 
A1  - Molloy, KJ 
T1  - Quinquedentate Coordination of 3-[(2'-Amino-ethyl)amino]-2-[(2&#8243;-aminoethyl)aminomethyl]propionic Acid (LH). Crystal Structure of <I>trans</I>-[Co(L)Cl][ClO<sub>4</sub>].H<sub>2</sub>O And Molecular Mechanics Examination of Isomers
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1994
VL  - 47
IS  - 5
SP  - 817
EP  - 827
KW  - 
UR  - https://doi.org/10.1071/CH9940817 
N2  - The anion (1c) of the branched polyamino acid 3-[(2&#8242;-aminoethyl)amino]-2-[(2&#8243;-aminoethyl)- aminomethyl ] propionic acid (1b) binds as a quinquedentate ligand to cobalt(III). Reaction with cobalt(II) chloride, followed by oxidation and acidification, yields exclusively one isomer of [Co(1c) Cl ]+. The complex was crystallized readily as a perchlorate monohydrate salt, in the monoclinic space group P 21/n, a 7.921(2), b 17.357(4), c 11.852(4) &#506;, &#946; 107.25(2)&#176;, Z = 4; a single-crystal X-ray structure determination was refined to R 0.033 for 2099 `observed' reflections. The carboxylate and two adjacent secondary amines occupy an octahedral face, with the chloro  ligand trans to the carboxylate , and the secondary amines adopt R,S stereochemistries. The Co-O distance [1.901(2) &#506;] is at the short end of the range of cobalt- carboxylate bonds, and Co-N distances [average 1.944 &#506; (primary amines), average 1.950 &#506; (secondary amines)] are slightly shorter than average for Co-N bonds. The Co- Cl distance is 2.255(1) &#506;. Molecular mechanics examination of all possible isomers and conformers of [Co(1c) Cl ]+ and of the related pentaamine  1,5,9-triamino-5-methyl-3,7-diazanonane (2) indicate a greater variation in strain energy across the range of isomers and conformers in the latter more strained system. 
ER  -

