New tetradentate Schiff base-oxovanadium(IV)complexes, [VO{3-Xsal-(
R,R)-2,4-ptn}](H
2{3-Xsal(
R,R)-2,4-ptn}:
N,N'-di-3-Xsalicylidene-(
R,R)-2,4-pentanediamine;X = EtO (ethoxy), MeO (methoxy), and H) were preparedand characterized. Only an orange polymeric form was obtained forthe 3-methoxy and nonsubstituted (X = H)complexes. Both orange polymeric (
1) and greenmonomeric (
2) crystals were obtained for the 3-ethoxysubstitutedcomplex. X-ray structure analyses of
1 and
2were carried out. Crystal data:[VO{3-EtOsal-(
R,R)-2,4-ptn}]·H
2O(
1),VO
6N
2C
23H
30,orthorhombic,
P2
12
12
1,
a = 13.764(4) Å,
b = 21.544(4) Å,
c = 7.682(5) Å,
Z = 4;[VO{3-EtOsal-(
R,R)-2,4-ptn}] (
2),VO
5N
2C
23H
28,orthorhombic,
P2
12
12
1,
a = 10.393(2) Å,
b = 22.278(2) Å,
c = 9.886(2) Å,
Z = 4. The orange crystals (
1) havewater of crystallization, and the complexes take a polynuclearlinearchain structure (···V=O···V=O···) with asix-membered N-N chelate ring in a chair form. The greencrystals(
2) have no water of crystallization, and the complexes takea mononuclear square-pyramidal structure with asix-membered N-N chelate ring in a flattened boat form. Uponheating at 170
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C for 10 min, orange
1 turnedto green
2, which reverted to orange
1 bysuspension in water-acetonitrile. Mechanism of theinterconversionbetween the polymeric and monomeric forms is discussed on the basis oftheir crystal structures.