New Organotin(IV) Complexes with a Potentially Multi-Site Ligand Based on the Cyclotriphosphazene Platform: Synthesis and Spectral Studies

A functionalized cyclotriphosphazene with four pyrazolyl substituents, N3P3(MeNC2H4O)(dmp)4 where dmp = 3,5-dimethylpyrazole, has been synthesized and characterized. The reaction of this potentially multi-site coordinating cyclotriphosphazene with diorganotin(IV) dichlorides, SnR2Cl2 (R = Ph, Me), leads to dinuclear [(SnPh2Cl2)2{N3P3(MeNC2H4O)(dmp)4}] (1) and mononuclear [(SnMe2Cl2){N3P3(MeNC2H4O)(dmp)4}] (2) complexes. These new compounds were characterized by elemental analysis and IR, 1H, 31P and 119Sn NMR spectroscopy. On the basis of these data, in the complex 1 pyrazolylcyclotriphosphazene acts as a bis-bidentate ligand and coordinates to two SnPh2Cl2 molecules via two geminal pyrazolyl nitrogen atoms. As for complex 2, coordination to one SnMe2Cl2 molecule occurs through two nongeminally substituted pyrazolyl nitrogens. The 119Sn NMR data are consistent with the increasing of coordination number of tin(IV) in solution