N-Heterocyclic Germylenes and Stannylenes with a 1,1′-Ruthenocenylene Backbone, Including an Example with a Ru→Sn Bond

High Resolution Image Download MS PowerPoint Slide The unusually high reactivity of [3]ferrocenophane-type N-heterocyclic tetrylenes fc[(NR) 2 E] (fc = 1,1′-ferrocenylene, E = Si–Pb) reflects a particularly pronounced ambiphilicity due to the large E II bond angles caused by the fc backbone. We describe the use of a 1,1′-ruthenocenylene (rc) backbone to further increase the E II bond angle and achieve an even stronger ambiphilicity. We have developed a synthesis for 1,1′-diaminoruthenocene, thus opening the door to the target ruthenocene-based N-heterocyclic tetrylenes. For a start, we have focused on germylenes and stannylenes with N -silyl substituents. A comparison of the structures of the ferrocene-based congeners fc{[N(Si t BuMe 2 )] 2 E} (E = Ge, Sn) with those of the ruthenocene-based analogues rc{[N(Si t BuMe 2 )] 2 E} has revealed two effects. In the case of the germylenes, the desired widening of the Ge II bond angle is observed. The stannylenes demonstrate that the larger radius of Ru vs Fe is favorable for intermetallic bonding, leading to tricoordinate tin in rc{[N(Si t BuMe 2 )] 2 Sn} due to a dative Ru–Sn II bond.