Novel diastereoisomers of ethylenediaminetetrapropionato-chromate(III) Part 2. X-Ray structures of diaminetripropionato complexes

Abstract

The crystal structures of the complexes [Cr{(S)-pdtrp}(H₂O)]1[(S)-pdtrp =(S)-propane-1,2-diamine-N,N,N′-tripropionate] and [Cr{(SS)-cydtrp}(H₂O)]2[(SS)-cydtrp =(1S,2S)-trans-cyclohexane-1,2-diamine-N,N,N′-tripropionate] were determined by X-ray diffraction methods: 1, monoclinic, space group P2₁a= 13.474(9), b= 9.867(3), c= 14.506(5)Å, β= 105.85(3)° and Z= 4; 2, triclinic, space group P1, a= 13.938(7), b= 14.016(6), c= 13.901(4)Å, α= 106.24(3), β= 112.50(3), γ= 73.21(4)° and Z= 4. The two complexes have the same geometrical structure, trans-equatorial, where two propionato chelates attached to the tertiary amine are co-ordinated meridionally. This structure substantiates that the anomalous C–N bond rupture observed in the two of the three diastereoisomers of [Cr(edtp)]^–(edtp = ethylenediamine-N,N,N′,N′-tetrapropionate) type complexes occurs at the R (relaxed) out-of-plane ring, not at the G (girdling) in-plane ring.