Synthesis of binuclear platinum complexes containing the ligands 8-naphthyridine, 2-aminopyridine, and 7-azaindolate. An experimental study of the steric hindrance of the bulky pentafluorophenyl ligands in the synthesis of binuclear complexes.
The bidentate N-donor ligands 2-aminopyridine (2-ampy), 7-azaindolate (aza) and 1,8-naphthyridine (napy) have been used to study the steric effect of pentafluorophenyl groups in the synthesis of binuclear platinum(II) complexes. The 2-ampy and aza ligands bridge two "Pt(C 6F 5) 2" fragments with Pt...Pt distances of 4.1 and 3.4 A, respectively (complexes 1 and 3). Under the same reaction conditions the napy ligand shows chelating behavior and makes the mononuclear complex ( A) highly reactive because of its strained coordination. One of the Pt-N bonds of the chelating complex is broken on reaction with HX {X = Cl ( 4), Br ( 5)} because of protonation while the anion X (-) occupies a created vacant site. The resulting mononuclear complex eliminates C 6F 5H when refluxed, and a binuclear complex ( 6) with two napy ligands bridging two "Pt(C 6F 5)Cl" fragments is obtained. The reaction of A with HPPh 2 affords a mononuclear complex ( 7) analogous to complexes 5 and 6, but reflux gives a binuclear complex ( 8) with the two napy ligands terminally bound and the PPh 2 groups bridging the "Pt(C 6F 5)napy" moieties. The reaction of A with HCCPh gives a binuclear complex; moreover, the final product does not depend on the ratio of complex A to HCCPh. Complexes 1, 4, 6, 9 have been structurally characterized by X-ray diffraction.
Casas
José M
JM
Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-C.S.I.C., E-50009 Zaragoza, Spain.
Diosdado
Beatriz E
BE
Forniés
Juan
J
Martín
Antonio
A
Rueda
Angel J
AJ
Orpen
A Guy
AG