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Synthesis, Structure, and Spectroscopy of the Biscarboranyl Stannylenes ( bc )Sn·THF and K 2 [( bc )Sn] 2 ( bc = 1,1'( ortho -Biscarborane)) and Dibiscarboranyl Ethene ( bc )CH=CH( bc ).

Alice C PhungJames C FettingerPhilip P Power
Published in: Organometallics (2023)
Two compounds containing a Sn(II) atom supported by a bidentate biscarborane ligand have been synthesized via salt metathesis. The synthetic procedures for ( bc )Sn·THF ( bc = 1,1' ( ortho -carborane) ( 1 ) and K 2 [( bc )Sn] 2 ( 2 ) involved the reaction of K 2 [ bc ] with SnCl 2 in either a THF solution ( 1 ) or in a benzene/dichloromethane solvent mixture ( 2 ). Using the same solvent conditions as those used for 2 but using a shorter reaction time gave a dibiscarboranyl ethene ( 3 ). The products were characterized by 1 H, 13 C, 11 B, 119 Sn NMR, UV-vis, and IR spectroscopy, and by X-ray crystallography. The diffraction data for 1 and 2 show that the Sn atom has a trigonal pyramid environment and is constrained by the bc ligand in a planar five-membered C 4 Sn heterocycle. The 119 Sn NMR spectrum of 1 displays a triplet of triplets pattern signal, which is unexpected given the absence of a Sn-H signal in the 1 H NMR, IR spectrum, and X-ray crystallographic data. However, a comparison with other organotin compounds featuring a Sn atom bonded to carboranes reveal similar multiplets in their 119 Sn NMR spectra, likely arising from long-range nuclear spin-spin coupling between the carboranyl 11 B and 119 Sn nuclei. Compound 3 displays structural and spectroscopic characteristics typical of conjugated alkenes.
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