Stabilizing the [RSn(μ2-O)SnR] Motif through Intramolecular N→Sn Coordination. Synthesis and Characterization of [(RSn)2(μ2-O)(μ2-FcCOO)2(η-FcCOO)2]•THF and {(RSn)2(μ2-O)[(t-BuO)2PO2]2Cl2}•THF•2H2O (R=2-(Phenylazo)phenyl)

The reactions of RSnCl3 (1; R = 2-(phenylazo)phenyl) with FcCOOH or di-tert-butyl phosphate in refluxing THF afforded the monoorganodistannoxanes [(RSn)(2)(mu(2)-O)(mu(2)-FcCOO)(2)(eta-FcCOO)(2)]center dot THF (2) and {(RSn)(2)(mu(2)-O)[(t-BuO)(2)PO2](2)Cl-2}center dot THF center dot 2H(2)O (3). The molecular structure of 2 contains seven-coordinate tin centers in a distorted-pentagonal-bipyramidal geometry, while 3 contains six-coordinate tin centers in a distorted-octahedral geometry. In the dinuclear compounds 2 and 3 the two tin centers are bridged by a mu(2)-O unit, affording a rare Sn-O-Sn motif among monoorganostannoxanes. In addition, each tin is also intramolecularly coordinated to the nitrogen atom of the 2-phenylazophenyl substituent (N -> Sn). Further, in 2, the two tin centers are bridged by two isobidentate ferrocenecarboxylate ligands; each tin center also is bound to a chelating ferrocenecarboxylate ligand. On the other hand, in 3, while the two tin centers are bridged by two isobidentate di-tert-butyl phosphate ligands, each tin center also has a terminal chloride ligand.