Triple Bonding to Tin: Synthesis and Characterization of the Square-Pyramidal Stannylyne Complex Cation [(dppe)2W⋮Sn−C6H3-2,6-Mes2]+(dppe = Ph2PCH2CH2PPh2, Mes = C6H2-2,4,6-Me3)

The reaction of trans- [W(dppe) 2 (N 2 ) 2 ] ( 1 ) with the m -terphenyl tin(II) chloride {Sn(Cl)(C 6 H 3 -2,6-Mes 2 )} 2 ( 2 ) affords by elimination of dinitrogen the 18-electron stannylyne complex trans- [Cl(dppe) 2 W⋮Sn−C 6 H 3 -2,6-Mes 2 ] ( 3; dppe = Ph 2 PCH 2 CH 2 PPh 2, Mes = C 6 H 2 -2,4,6-Me 3 ). Chloride abstraction occurs readily from 3 with TlPF 6 to give the cationic 16-electron stannylyne complex [(dppe) 2 W⋮Sn−C 6 H 3 -2,6-Mes 2 ]PF 6 ( 4 ), which dissolves in acetonitrile- d 3 to give the cationic 18-electron stannylyne complex trans- [(CD 3 CN)(dppe) 2 W⋮Sn−C 6 H 3 -2,6-Mes 2 ]PF 6 ( 5 ). The complexes 3 and 4 reveal by X-ray crystallography a very short W−Sn triple bond (2.504(1) Å ( 3 ), 2.4641(7) Å ( 4 )) and a linear geometry at the tin atom (W−Sn−C aryl = 175.88(8)° ( 3 ), 178.77(9)° ( 4 )). Comparative quantum-chemical analyses of the W−E triple bonds of the model compounds trans- [Cl(PH 3 ) 4 W⋮E−Me] (E = C, Sn) are presented.