Vinylidene-, Alkynyl-, and trans-Bis(alkynyl)ruthenium Complexes. Crystal Structure of trans-[Ru(NH3)(C⋮C−Ph)(Ph2PCH2CH2PPh2)2]PF6

Abstract

A variety of vinylidene−ruthenium complexes [trans-RuCCHR(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, nBu, 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.