First Example of Zinc(II) Monomeric Species Stabilized by η2-Bonded Alkynes

Monomeric ZnX 2 (X = Cl, Br) moieties have been stabilized by alkynes through the reaction of [Ti](C⋮CR) 2 (R = SiMe 3 ( 1 ), Fc ( 2 ); Fc = (η 5 -C 5 H 4 )Fe(η 5 -C 5 H 5 ), [Ti] = (η 5 -C 5 H 4 SiMe 3 ) 2 Ti) with the anhydrous Zn(II) salts ZnX 2 (X = Cl ( 3 ), Br ( 4 )). The resulting heterodinuclear complexes of formula {[Ti](C⋮CR) 2 }ZnX 2 (R = SiMe 3, X = Cl ( 5a ), Br ( 5b ); R = Fc, X = Cl ( 6a ), Br ( 6b )) could be obtained in high yield. The identities of all new complexes have been confirmed by analytical and spectroscopic (IR, 1 H and 13 C{ 1 H} NMR) data. Additionally, the structure of complex 6b has been established by X-ray diffraction. Two different orientations within the molecule have been encountered ( 6b 1 and 6b 2 ). The solid-state structure of 6b clearly demonstrates η 2 coordination of the FcC⋮C ligands to ZnBr 2, resulting in a pseudotetrahedral surrounding of the zinc(II) center, whereby the zinc atom is in-plane bonded with the Ti(C⋮C) 2 moiety. Additionally, the electrochemical behavior of {[Ti](C⋮CR) 2 }ZnBr 2 (R = SiMe 3, Fc), in which early- and late-transition-metal atoms are linked via σ,π-coordinated alkyne ligands, is reported.