Synthesis and Thermal Investigations of Eleven-Membered Ring Systems Containing One of the Heavier Group 14 Element Atoms Si, Ge, and Sn.Unique eleven-membered rings containing silicon, germanium, and tin were synthesized in good yields by the reactions of the corresponding 1,2-bis((2-bromothiophen-3-yl)methoxy)benzenes with (C6H5)2ECl2 where E = Sn, Ge, Si.  Thermal analysis investigations (TGA and DSC methods) of these eleven-membered rings suggested the loss of a phenyl group in the first decomposition step. 
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