Propylenediamine complexes

Isomer Ratios for Cobalt(III) Ethylenediamine and (—)-Propylenediamine Complexes (13)... 

The corresponding propylenediamine complexes are similarly prepared, using the equivalent amount of amine. The yield of all these preparations is over 90%. 

Bis(propylenediamine) complexes with the four nitrogen atoms in the square planar configuration usually adopt the tram methyl (equatorial) configuration253-255 (15), but in Pt(.R-pn) + one methyl group is axial (16).256... 

Lifschitz (39) isolated both optical isomers of a-[Co(L-alaninate)3] (meridional), and recently both optical isomers of the P (facial) isomer have been isolated in four laboratories. Bailar (3) isolated both isomers of [Co( —)pn2C03]". He and several of his students have used the selective substitution in such optically active complexes of pn and en by a racemic mixture of a ligand to resolve partially the ligand. Dwyer studied the tris(propylenediamine) complexes of Co(III) (16) and Pt(IV) (17) and found that their formation is not absolutely stereospecific, as previously believed. 

Diamines. Chromatography has been used to isolate three isomers of trans- and cis-[Co(CN)2 (RR)-cyclohexane-l,2-diamine 2] and five isomers of the corresponding propylenediamine complexes. Mer- and /ac-isomers of tris(meso-pentane-3,4-diamine)cobalt(iii) have been prepared and separated using column chromatography. The rates of aquation of three isomers of [CoCl(tmd)(dien)] and one isomer of [CoCl(tmdXdpt)] have been measured and the kinetic parameters calculated [dpt = NH2(CH2)3NH(CH2)3NH2, tmd = NH2(CH2)3NH2]. The interaction of [Co(dien)2] with sulphate, thiosulphate, sulphite, selenite, tellurite, and carbonate ions has been studied potentiometrically and stability constants determined for the outer-sphere complexes. The i.r. spectrum of octahedral... 

Figure 2. Condensation reaction of metalfll)-propylenediamine complexes with acetone (M=Ni(II) or Cu(II))...

If one accepts this argumentation which has been strongly reinforced by the investigations of 1-propylenediamine complexes by SAITO et al. (2,3). 

Sato J, Jin H, Omata K, Kabuto K, Sasaki Y. Resolution of enantiomer signals by diamagnetic lanthanum(III)-A,A,Ar, N -tetrakis(2-pyridinylmethyl)-(R)-propylenediamine complex in H NMR. Enantiomer, 1999 4 147-150. 

This series of salts is yellow or brown in colour, and consists of the true hexammino-eompounds, and also compounds where all, or part, of the ammonia is replaced by ethylenediamine or propylenediamine. Every molecule of ethylenediamine or propylenediamine replaces two molecules of ammonia, and thus occupies two co-ordination positions in the complex. A few compounds are known where urea replaces ammonia in the complex, and in this case one molecule of urea replaces one molecule of ammonia, and occupies one co-ordination position only. 

A series of salts is known of the above type where ethylenediamine and propylenediamine enter the chromic complex, giving rise to mixed salts. This series was described by Pfeiffer in 1908.6... 

As with the carbocyclic systems, the hydrogens on both N and C adopt axial and equatorial positions, and in the change from one conformer to the other the axial H inverts to the equatorial position and vice versa. There are many examples of ring systems in coordination chemistry which can adopt these conformational isomeric positions. Four systems currently being studied are the complexes of 1,2-propylenediamine, 1,2-f/ww-cyclo-hexanediamine, 1,2-fraw.y-cyclopentanediamine, and 2,3-butanediamine, and some reference will be made to each of these. 

Figure 5. The absolute configuration of d-(—)-propylenediamine and the conformations of this ligand in the d configuration of the complex.

Equilibrium Concentrations of Cobalt(III) Complexes for Varying Ratios of Ethylenediamine and (-)-Propylenediamine (13)... 

Figure 15. Proton magnetic resonance spectra of cobalt(III) complexes containing ethylenediamine and/or (— )-propylenediamine (33). (100-mc TMS external reference...

The aqueous CD curves for Co(III) complexes containing ethylene-diamine and/or ( — )-propylenediamine are given in Fig. 20. The order of magnitude of the CD in the region of the first ligand-field band is similar to... 

Figure 20. The circular dichroism and absorption spectra of cobalt(III) complexes containing (-)-propylenediamine and/or ethylenediamine (in aqueous solution).

Since many ligands are organic compounds which have possibilities for isomerism, the resulting complexes can show isomerism from this source. Examples of isomeric ligands are 1,2-diaminopropane ( propylenediamine, pn) and 1,3-diaminopropane C trimethylenediamine, tn) or ortho-, meta-, and pcra-toluidine fCH3C6H4NH2). 

Propionohydroxamic acid metal complexes, 506 Propylenediamine metal complexes, 34 Protactinium complexes cupferron, 510 Proteins... 

However, a number of tris-chelate mixed ligand Cr(III) complexes do exhibit a correlation of the same signs between the lowest frequency 2E component and the major 4E component.119,120,122,123 This relation has been verified by examining the CD for diastereomers of [Cr(en)x(diamine)3 x]3 + (x = 0, 1, 2), c/i-[Cr(NH3)2 (diamine)2]3 +, where the diamines used were (R)- or (5)-propylenediamine and (IR,2R)- or (15,250-1,2-traras-cyclohexanediamine. The differences in CD patterns between each pair of the diastereomers were accounted for by separability and additivity of the configurational and conformational CD contributions. The CD in the spin-allowed 4T2 <— 4A2 transitions shows a positive major component (4E) for the configurational contribution and a minor negative (4Ai) and major positive (4E) components from the lower frequency side for the conformational contribution as shown in Figure 5.30. 

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