Chemistry Reference
In-Depth Information
4.3.2 2 D Coordination Polymers
Nucleobases and Anions as Bridging Ligands.
The examples of 2D covalent frameworks, based on the coordinative properties of
the nucleobases, are rare. No examples with only bridging nucleobase bidimensional
networks have been described to date. The two cases encountered in the CSD data-
base exhibit cooperative bridging of a nucleobase and of an auxiliary anion. Lippert
et al.
reported the fi rst of these two cases in which
trans
- [Pt(CH
3
NH
2
)
2
(cytosinato -
N1
)(cytosinato -
N3
)] molecules are cross-linked by Cu
II
ions through the still avail-
able N3 and N1 positions of the cytosine ligands to give a 1D coordination polymer.
These · · · Pt - cytosinato - Cu - cytosinato - Pt · · · chains are further cross-linked by means
of double m - hydroxo bridges between Cu
II
atoms belonging to adjacent chains
leading to the overall corrugated 2D crystal structure (Figure 4.33).
38
The 2D
extended solid-state structure can also be described as fused rings comprised of 4
Pt and 6 Cu metal centres.
Verma and Purohit recently reported a 2D framework constructed from 9-
allyladenine and silver nitrate.
39
Its asymmetric unit contains distorted tetrahedral
Figure 4.33
Section of the 2D heteronuclear [
trans
-[Pt(CH
3
NH
2
)
2
(
µ
-cytosinato-N1,N3)(
µ
-
cytosinato-N3,N1)Cu(OH)]ClO
4
·1.2H
2
O coordination complex
