Low-weight coordination polymers derived from the self-assembly reactions of Pd(II) pyrazolyl compounds and azide ion

• DOI: 10.1016/j.poly.2005.03.043
• Publication Date: 2005-05-27T11:02:16Z
• Authors: A.V.G. Netto; R.C.G. Frem; A.E. Mauro
• Keywords: Isostructural; Metallacycle; Coordination polymer

Abstract The low-weight Pd(II) coordination polymers [(N 3 )(HL)Pd {Pd 3 (μ-N 3 )(μ-L) 5 } 10 (μ-L) 2 Pd(L)(HL)] {L = Pz − ( 1 ); mPz − ( 2 ), IPz − ( 3 )} and [(N 3 )(HPz)Pd{Pd 6 (μ-N 3 ) 2 (μ-Pz) 5 (μ-L) 5 } 10 (μ-L) 2 Pd(Pz)(HPz)] {L = mPz − ( 4 ), dmPz − ( 5 ); IPz − ( 6 )} {L = pyrazolate (Pz − ), 4-methylpyrazolate (mPz − ), 4-iodopyrazolate (IPz − ), 3,5-dimethylpyrazolate (dmPz − )} have been prepared in this work. IR spectra clearly indicated the exobidentate nature of pyrazolato ligands as well the end-on coordination mode of the azido group. The molecular weight determinations by osmometry indicated that the species have a low degree of polymerization ( n = 10). NMR experiments showed two pyrazolate environments in a 2:1 ratio, being assigned to the six-membered ring Pd(μ-L) 2 Pd and the Pd(μ-N 3 )(μ-L)Pd metallocycle, respectively. UV–visible spectroscopy gave further evidences for the oligomeric structures of 1 – 6 . Some alternative structures for the isostructural polymers have been suggested.