Vinylidene-, alkynyl-, and trans-bis(alkynyl)ruthenium complexes. Crystal structure of trans-[Ru(NH3)(C C-Ph)(Ph2PCH2CH2PPh2)(2)]PF6

A variety of vinylidene-ruthenium complexes [trans-Ru=C=CHR(Cl)(dppe)(2)]PF6 (2) are obtained by reaction of RuCl2(dppe)(2) (1) with terminal alkynes and NaPF6. On treatment with a base, complexes 2 afford the alkynyl-ruthenium derivatives trans-Ru-C=C-R(Cl)(dppe)(2) (3). trans-Ru(C=CR)(2)(dppe)(2) 4 are prepared under mild conditions via the reaction of RuCl2(dppe)(2) with terminal alkynes HC=C-R (R = Ph, Bu-n, SiMe3, C10H21, CH2OSiMe3, CH2OMe) in the presence of an excess amount of NaPF6 and NEt3, whereas trans-Ru(C=CH)(2)(dppe)(2) (5) was obtained directly from HC=C-SnBu3 and precursor 1. In contrast, unsymmetrically substituted complexes trans-Ru(C=CR1)(C=CR2)(dppe)(2) (6) were built from the vinylidenes 2 in the presence of another alkyne, NaPF6, and NEt3. On protonation with NH4+PF6-, the bis(alkynyl) derivatives 4 lead to the release of RC=CH and the formation of trans-[Ru(NH3)(C=CR)(dppe)(2)]PF6 complexes 7. The structure of trans-[Ru(NH3)(C=CC6H5)(Ph2PCH2CH2PPh2)]PF6 (7a) has been determined by X-ray diffraction.