Novel seven coordination geometry of Sn(IV): Crystal structures of phthalocyaninato bis(undecylcarboxylato)Sn(IV), its Si(IV) analogue, and phthalocyaninato bis(chloro)silicon(IV). The electrochemistry of the Si(IV) analogueand related compounds

Three newly elucidated crystal structures of group IV phthalocyaninato comp lexes are reported, along with data for two further Sipe carboxylate comple xes. In one of these crystal structures, bis(undecylcarboxylate)Sn(IV) phth alocyanine, the tin ion is seven coordinate, which is a unique finding for this atom in phthalocyanine ring coordination. Comparison of these structur es with other group IV phthalocyaninato and related structures reveals diff erences, illustrating features significant in the chemistries of Si(IV) and Sn(IV) ions. These differences are thought to originate from their differi ng sizes and polarizabilities. The structures show that the Sn(IV) ion can only occupy an in-plane location in the phthalocyaninato ring where it elon gates toward the two axial ligands. When the axial ligands do not facilitat e this elongation cis coordination is preferred and the Sn(IV) ion sits abo ve the phthalocyaninato ring plane. In contrast, the Si(IV) structures, wit h smaller, harder (i.e., less polarizable) Si(IV) ions, are six coordinate with the Si(IV) ion in the phthalocyaninato ring plane in a distorted octah edral symmetry. The electronic spectra and cyclic voltammetry of some of th e Si compounds indicate that on the electrode the oxidized/reduced species behave as though they are in a solid film, rather than a soluble freely dif fusing species.