Isolable zero-valent Ditin(0) and Diplumbum(0) complexes

Although complexes with monatomic zero-valent main group centers have been reported, diatomic zero-valent complexes are extremely rare and all previously reported examples were stabilized by either carbene or silylene ligands. Here, we present the isolation of diatomic E(0)-E(0) (E = Sn, Pb) species supported by two [N{CH₂CH₂NPiPr₂}₃Sn] fragments. The reaction of trilithium salt N{CH2CH2NLiPiPr2}3 with SnCl2 yields complex [N{CH2CH2NPiPr2}3]2Sn3 (1) with a Sn3 chain. The reduction of the mixture of 1 and SnCl2 with KC8 produces the catenated Sn4 chain [N{CH2CH2NPiPr2}3Sn2]2 (2), featuring a diatomic Sn(0)-Sn(0) unit. Further reduction of 2 with KC8 yields the alkali metal ion-bridged complex [N{CH2CH2NPiPr2}3SnK]2 (3). Moreover, the reaction of 3 with PbI2 and KC8 affords [N{CH2CH2NPiPr2}3SnPb]2 (4), which can also be generated by the reaction of KC8 with PbI2 and [N{CH2CH2NPiPr2}3SnLi]2 (5). Complex 4 features a diatomic Pb(0)-Pb(0) unit, representing a heavy diatomic zero-valent main group complex. The presence of diatomic E(0)-E(0) (E = Sn, Pb) units in complexes 2 and 4, respectively, is further confirmed by computational studies.