Di‐ and Trinuclear Alkyne‐ and Vinylidenerhodium(I) Complexes Including the X‐ray Crystal Structure of a Dendrimer‐Like Rh3 Compound

The dimer [RhClL2]2 (1; L = PiPr3) reacts with 1,3,5-C6H3(C≡CH)3 to give in the initial step the tris(alkyne)trirhodium compound 2, which rearranges in toluene at 60 °C to yield the isomeric tris(vinylidene) complex 3. Treatment of either 2 or 3 with pyridine affords the trinuclear tris(alkynyl)trihydridorhodium(III) complex 4. The trisilyl derivative 1,3,5-C6H3(C≡CSiMe3)3 reacts with 1 to form the mononuclear compound 5, in which only one of the C≡C bonds is coordinated to Rh. The diynes 1,3- and 1,2-C6H4(C≡CH)2 behave analogously to 1,3,5-C6H3(C≡CH)3 and upon treatment with 1 yield initially the bis(alkyne)dirhodium complexes 6 and 7 and subsequently the bis(vinylidene)dirhodium isomers 8 and 9. The reactions of 1,2-, 1,3-, and 1,4-C6H4(C≡CSiMe3)2 with 1 take a similar course and give the bis(alkyne) and bis(vinylidene) compounds 10–12 and 13–15, respectively. In the same way, the dinuclear bis(alkyne) and bis(vinylidene) complexes 16 and 17 have been prepared from 1 and the naphthalene derivative 1,5-C10H6(C≡CH)2. The molecular structures of 17 and of the dendrimer-like Rh3 compound 3 have been determined by X-ray crystallography.