Gold and Silver Chains Supported by Linear Hexaphosphine Ligands

A new linear hexaphosphine, rac‐cis,cis,trans ‐ bis{[(diphenylphosphinomethyl)phenylphosphinomethyl]phenylphosphino}methane ( P 6 ), was synthesized and isolated as a pure isomer, confirmed by transforming to the corresponding phosphine sulfide. The methylene‐bridged linear hexaphosphine readily organized flexible gold(I) and silver(I) hexanuclear chains, [M 6 (μ‐ P 6 ) 2 ]X 6 (X 6 =(OTf) 6 , M=Au ( 1 ), Ag ( 2 ); X 6 =Cl 2 (PF 6 ) 4 , M=Au ( 3 )). The hexaphosphine also supported a tetrasilver(I) complex [Ag 4 (μ‐ P 6 ) 2 ](OTf) 4 ( 4 ), which was readily transformed by treatment with AgOTf into 3 , revealing a drastic alternation of the two P 6 arrangement. The hexagold(I) chains exhibited a considerably red‐shifted absorption (∼410 nm) and emission (540–580 nm) to 1 [5d σ* →6p σ ] and from 3 [5d σ* →6p σ ] excited states of the metal centers, respectively. The new linear hexaphosphine could be a useful tool to construct linear metal clusters as subnano building blocks.