X-RAY CRYSTAL-STRUCTURE OF A TERNARY COPPER(II) PEPTIDE CREATININE COMPLEX, (AQUO)(CREATININE)(GLYCYLGLYCINATO) COPPER(II) SESQUIHYDRATE

The first creatinine ternary complex [Cu(gg)(H2O)(creat)]. 1.5 H2O (1) [gg = glycylglycine (2-), creat = creatinine] has been crystallized f rom aqueous solution. The coordination geometry about the copper is ap proximately square pyramidal with the tridentate glycylglycine dianion and the N(1) of creatinine occupying the corners of a square. The coo rdination sphere about the copper is completed by an axial water molec ule, Cu-OW(1) distance 2.496(2) Angstrom. Another water molecule OW(2) , Cu-OW(2) distance 2.907(2) Angstrom. extends qualitatively the coord ination geometry to octahedral. A third water molecule OW(3) with an o ccupancy factor of 0.5 is disordered and is located between two comple x units. The complete crystal structure is maintained by an extensive hydrogen-bonding network in which the three types of water molecules a re involved.