On the occurrence of 119Sn-CIDNP during some reactions of trimethylstannyl radicals

The ¹¹⁹Sn nuclei of hexamethylditin, formed during the photochemical reaction of trimethyltin hydride with d₁-t-butyl peroxide or dibenzyl ketone, or during the thermal decomposition of azodusobutyronitrile with trimethyltin hydride, exhibit CIDNP. The nuclear polarisation is built up in radical pairs $\text{Me}{}_3\text{Sn··SnMe}{}_3$¹. The full CKO theory has to be used for explaining the net effect in the main ¹¹⁹Sn signals of the hexamethylditin. The high field approximation is not valid because of the high value of the ¹¹⁹Sn hyperfine splitting in trimethylstannyl radicals. The multiplet effect in the ¹¹⁷Sn satellites is interpreted in terms of the high field treatment. A negative sign is found for a_117Sn(Me₃Sn) and a_119Sn(Me₃Sn). ¹¹⁹Sn-CIDNP also appears in benzyltrimethyltin during photolysis of dibenzylketone with trumethyltin hydride. It is concluded from ¹H-CIDNP investigations that nuclear polarisations built up in radical pairs containing both stannyl radicals and others are not observed in hexamethylditin. A positive sign is found for

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