Controlling Catenation in Germanium(I) Chemistry through Hemilability

We present a novel approach for constructing chains of Group 14 metal atoms linked by unsupported metal–metal bonds that exploits hemilabile ligands to generate unsaturated metal sites. The formation/nature of catenated species (oligo‐dimetallynes) can be controlled by the use of (acidic/basic) “protecting groups” and through variation of the ligand scaffold. Reduction of Ar(NiPr2)GeCl (Ar(NiPr2)=2,6‐((i)Pr(2)NCH(2))(2)C(6)H(3))—featuring hemilabile N(i)Pr(2) donors—yields (Ar(NiPr2)Ge)(4) (2), which contains a tetrameric Ge(4) chain. 2 represents a novel type of a linear homo‐catenated Ge(I) compound featuring unsupported E−E bonds. Trapping experiments reveal that a key structural component is the central two‐way Ge=Ge donor‐acceptor bond: reactions with IMe(4) and W(CO)(5)(NMe(3)) give the base‐ or acid‐stabilized digermynes (Ar(NiPr2)Ge(IMe(4)))(2) (4) and (Ar(NiPr2)Ge{W(CO)(5)})(2) (5), respectively. The use of smaller N‐donors leads to stronger Ge‐N interactions and quenching of catenation behaviour: reduction of Ar(NEt2)GeCl gives the digermyne (Ar(NEt2)Ge)(2), while the unsymmetrical system Ar(NEt2)GeGeAr(NiPr2) dimerizes to give tetranuclear (Ar(NEt2)GeGeAr(NiPr2))(2) through aggregation at the N(i)Pr(2)‐ligated Ge(I) centres.