Monoorganotin oxo-carboxylates

Not until X-ray diffraction studies were performed was their structure finally clarified. Now, two types of hexanuclear organotin oxo-carboxylates are known -hexamers of composition [RSnO(OOCR )]6, which have a hexagonal prismatic cage structure, 165, (or drum structure) and ladder type compounds, 166, of composition [ RSnO(OOCR ) 2 RSn(OOCR )2X ] (X = R COO or Cl) both contain Sn202 aggregates. The compounds have been reviewed (510). 

One variety of the ladder hexanuclear tin oxo-carboxylates, 167, contains three Sn202 moieties fused into an open structure, with carboxylate bridging and halogen atoms at tin. 

The compounds [ RSnO(OOCR ) 2(RSn(OOCR )3 ] with R = Me, R = cyclo-CgHn [514] R = Bu , R = Me, Ph [514] and cyclo-Ce w [513] and the chloro derivative [ Bu SnO(OOCPh) 2 Bu°Sn(OOCPh)2Cl ] [513] have been structurally characterized. In the latter, the chlorine substituent replaces a chelating (nonbridging) carboxylato group. 

The drum and ladder types are interconvertible, as demonstrated by Sn NMR spectroscopy in solution. The most stable form is the hexagonal prism, with the incompletely hydrolyzed ladder probably being an intermediate. 

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