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.