21 July 2021
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Coordination polymers og Hg(II) with 2,2'- bipyrimidine
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Emanuele Priola, Eliano Diana, Giuliana Gervasio, Elisabetta Bonometti, Roberto Rabezzana, Lorenza Operti
Dipartimento di Chimica Università di Torino
Via P. Giuria 7, Torino 10125 emanuele.priola@studenti.unito.it
n 1983 S. Lanza reported the preparation and spectroscopic characterization of a binuclear complex of 2,2’-bipyrimidine (bpym) with HgCl (Inorg. Chim. Acta, 1983, 75(1), 131). This work has been developed by 2
I
Jaradat, K. Barqawi and T.S. Akasheh in 1986 (Inorg. Chim. Acta, 1986, 116(1), 63), that prepared theomolo-gous with bromine and iodine and did a spectroscopic and electrochemical characterization of the comple-xes. Recently, a renovated interest on this kind of chelating ligand has been inspired by his flexibility in the formation of coordination polymers. Jing-Yun Wu, Hung-Yu Hsu, Chun-Chieh Chan, Yuh-Sheng Wen, Chiitang Tsai, and Kuang-Lieh Lu reported a brilliant synthesis of a layered structure obtained by interaction of HgCl and HgBr with 5,5’-bipyrimidine (Cryst. Growth Des., 2009, 9(1), 258):2 2
Q.
Bridging halogenide, interaction and interactions between aromatic rings have per-mitted to obtain a columnar structure based on a Hg-Cl-Hg coordination polymer.
mercuriophilic p-p
Hg
Hg
ecause of the interesting structural and luminescent properties usually shown by coordination
pol-10
ymers of d metals containing aromatic ligands, we decided to develop the study of the interactions
B
between 2,2-bipyrimidine and HgX compounds, where X=2 , , , , with the purpose to obta-in Hg (bpym)X complexes.2 4
-Cl I- CN- SCN
-he synt-hesis of t-he complexes has been executed by refluxing an acetonitrile solution of bpym and t-he appropriate mercury salt, in the ratio 1:2. The clear solution obtained has been slowly evaporated and
T
crystal suitable for XRD analysis have been obtained.[ -(2,2'-bipyrimidine-N1,N1':N3,N3')]tetrachlorodi
m
mercury
2.348 2.360 2.575 2.617 3.219 3.095Esa-coordinated Hg(II) geometry derives from a distorted tetrahedron with insertion of two chlorine atoms.
Bridgin chlorine and p-p interactions among bpym generates 1-D polymeric chains
1-D chains develop along crystallographic a axis and don’t interact each others
[ -(2,2'-bipyrimidine-N1,N1':N3,N3')]tetrakis(cyano)di
m
mercury
The cyanide complex is a molecular compound. Mercury has a distorted tetrahedral coordination. The stacking of bipym is stag-gered. A significant contribution to the crystalline packing comes from N×××H hydrogen bond between cyanide ligands and the wa-ter.
[ -(2,2'-bipyrimidine-N1,N1':N3,N3')]tetraiododi
m
mercury
Bridging iodide generate a 1-D coordination polymer
Ribbons of iodide-mercury-bpym are stacked thanks to weak p-p interaction between aromatic rings. The angle between
superposed C N rings is 15.5°4 2
In the iodide complex, Hg(II) is coordinated to five atoms: two bpym nitrogen, two bridging iodide, one terminal iodide.
2.606 3.330 2.608 2.681 2.740
[ -(2,2'-bipyrimidine-N1,N1':N3,N3')]tetrakis(thiocyanate)di
m
mercury
Thiocyanate ligand generate an interesting structure: mercury is penta-coordinate to three nitrogen ( two of bpym and one of
-
-SCN ) and to two sulfur. The ambidentate nature of -SCN permits the formation of a 3-D polymer
2.443 2.659 2.513 2.471 2.415 300 350 400 450 500 550 600 0 5000 10000 15000 20000 25000 30000 35000 40000 a r b it r a r y u n it s l(nm) E x c i t a t i o n - e m i s s i o n s p e c t r a o f ( b i py m ) H g ( S C N )2 4
The intense emission obtained upon excitation at 350 nm is under study, in order to discriminate the contribution of ligand transi-tion from those of the metal.
Infrared spectra of (bipym)Hg2(CN) (bottom) and bpym (top) with some significant assignments4
4000 3500 3000 2500 2000 1500 1000 500 wavenumber (cm-1) %T n(OH) d(HOH) d(HgCN) n(CºN)
Raman spectra of (bipym) Cl (red) and bpym (black). It’s possible to notice the effect of the coor-4 -1
dination on the vibrational modes of bpym ( the shift of ring modes in the range 1600-1400 cm and
-1 -1
at 1000 cm ), and the appearance of a strong mode at 280 cm , attributable to Hg-Cl stretching. Hg2 1600 1400 1200 1000 800 600 400 200 wavenumber (cm-1) r a m a n sc a tt e r in g
