Catalytic Synthesis and Characterization of Biodegradable ...
Catalytic Synthesis and Characterization of Biodegradable ...
Catalytic Synthesis and Characterization of Biodegradable ...
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Chapter 2<br />
Figure 2.1 Crystal structure <strong>of</strong> the L 1 -Co III -dnp complex.<br />
The geometry around the cobalt atom was octahedral with an almost linear axial<br />
O(2)–Co(1)–O(4) bond angle <strong>of</strong> 177.52(7)º, <strong>and</strong> nearly perpendicular for O(1)–Co(1)–O(3),<br />
O(3)–Co(1)–N(2), N(2)–Co(1)–N(1) <strong>and</strong> N(1)–Co(1)–O(1) <strong>of</strong> 88.03(7)º, 94.96(8)º, 83.29(8)º,<br />
<strong>and</strong> 93.71(7)º, respectively, for the equatorial donor atoms. The Co(1) atom deviated from the<br />
N(1)N(2)O(1)O(3) least-squares plane by only 0.0276 Å, representing the nearly ideal<br />
octahedral arrangement. The distances from the Co atom to the O(1), O(2), O(3), O(4), N(1)<br />
<strong>and</strong> N(2) atoms were 1.8969(15), 1.8868(15), 1.8964(16), 1.9672(16), 1.8985(18) <strong>and</strong><br />
1.902(18) Å, respectively (Table 2.1). Interestingly, the phenolate oxygen, O(3), is involved in<br />
the equatorial planed rather than the four donor atoms in the tetradentate Schiff-base lig<strong>and</strong>.<br />
Table 2.1 Selected bond distances <strong>and</strong> angles for L 1 -Co III -dnp.<br />
Bond Distance(Å) Bond Angle(º) Bond Angle(º)<br />
Co-N(1) 1.8985(18) O(1)-Co-O(2) 92.54(7) O(1)-Co-N(2) 176.99(7)<br />
Co-O(1) 1.8969(15) O(1)-Co-N(1) 93.71(7) O(2)-Co-N(1) 96.37(7)<br />
Co-O(3) 1.8964(16) N(2)-Co-N(1) 83.29(3) O(1)-Co-O(3) 88.03(7)<br />
Co-N(2) 1.9020(18) O(2)-Co-O(3) 86.58(6) N(2)-Co-O(3) 94.96(8)<br />
Co-O(2) 1.8868(15) N(1)-Co-O(3) 176.50(7) O(1)-Co-O(4) 87.41(7)<br />
Co-O(4) 1.9672(16) O(2)-Co-O(4) 177.52(7) N(2)-Co-O(4) 92.16(7)<br />
N(1)-Co-O(4) 86.11(7) O(3)-Co-O(4) 90.93(7)<br />
O(2)-Co-N(2) 88.03(7)<br />
The IR spectral data <strong>of</strong> the lig<strong>and</strong>s <strong>and</strong> the complexes in Table 2.2 showed major b<strong>and</strong>s<br />
around 1624 cm -1 assigned to the C=N stretching vibration (vC=N), <strong>and</strong> around 1610 cm -1 <strong>and</strong><br />
1525 cm -1 assigned to the ring vibrations. The peaks around 1566 cm -1 <strong>and</strong> 1327 cm -1 were<br />
assigned to the stretching <strong>of</strong> the N=O bonds, <strong>and</strong> the peaks around 1252 cm -1 <strong>and</strong> 1063 cm -1<br />
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