Donor-funktionalisierte Alkinyle von Titan(IV), Kupfer(I) und Silber(I); Festkörperstrukturen von [Ti](CCCH2NMe2)2 und {[Ti](CCtBu)2}CuCCCCC2H5

The preparation of numerous donor-functionalised acetylides with Ti(IV) and/or Group II transition metals is described. The reaction of [Ti]Cl2 (1) {[Ti]=(η5-C5H4SiMe3)2Ti} with two equivalents of LiCCR1 [2a: R1=CMeCH2; 2b: R1=C6H4CN-4; 2c: R1=CH2NMe2; 2d: R=C5H4N-4] affords the bis(alkynyl)titanocenes [Ti](CCR1)2 [3a: R1=CMeCH2; 3b: R1=C6H4CN-4; 3c: R1=CH2NMe2] in good yields. While by treatment of 1 with 2d in a 1:2 molar ratio only non-characterisable products are formed, the use of [Ti](Cl)(CH2SiMe3) (4) produces [Ti](CH2SiMe3)(CCC5H4N-4) (5) in excellent yields. Monomeric, donor-functionalised copper(I) acetylides of general type {[Ti](CCR1)2}CuCCR3 [R1=tBu, 7a: R3=CCCH2CH3; 7b: R3=CMeCH2; 7c: R3=C6H4CN-4; R1=SiMe3, 7d: R3=CMeCH2; 7e: R3=C6H4CN-4] are accessible by (i) the reaction of {[Ti](CCtBu)2}CuSC6H4CH2NMe2-2 (6) with equimolar amounts of 2a–2c or (ii) treatment of the monomeric copper(I) methyl {[Ti](CCR1)2}CuCH3 (8a: R1=SiMe3, 8b: R1=tBu) with HCCR3 [9a: R3=CCCH2CH3, 9b: R3=CMeCH2, 9c: R3=C6H4CN-4] in a 1:1 molar ratio. The reaction chemistry of these complexes towards selected transition metal compounds is described. The bis(alkynyl)titanocenes 3a–3c produce with MLn {10a: MLn=CuCl; 10b: MLn=CuI; 10c: MLn=[Cu(CH3CN)4][PF6]; 10d: MLn=AgBF4; 10e: MLn=Ni(CO)4} the heterobimetallic tweezer complexes {[Ti](CCR1)2}ML [R1=CMeCH2; 11a: ML=CuCl; R1=C6H4CN-4; 11b: ML=CuCl; 11c: ML=CuI; 11d: ML=Ni(CO); R1=CH2NMe2; 11e: ML=CuPF6; 11f: ML=AgBF4]. In complexes 11a–11f an early and a late transition metal centre [e.g. Ni(0)] are linked via the corresponding R1CC ligands of the organometallic π-tweezer complexes. For complexes 11e and 11f a dynamic behaviour is observed in solution. The solid state structures of 3c and 7a are reported. Both compounds crystallise in the triclinic space group . They exhibit features that are characteristic for this class of complexes: (i) a tetrahedral environment around the Ti(IV) of 3c and 7a, (ii) a lengthening of the CC triple bonds upon η2-coordination to the transition metal complex fragment CuCCCCC2H5, (iii) a trans-deformation of the TiCCtBu unit, and (iv) a reduction of the bite angle CCCTiCCC for 7a.