Reactions of three aryl-substituted phosphines with [Cp*MCl2]2 (M = Ir and Rh) have been carried out in the presence of sodium acetate. Aryl-substituted phosphine is cyclometalated readily to give the corresponding five-membered metallacycle complex via an intramolecular activation of C­(sp2)–H or C­(sp3)–H bond. Competition reaction indicates that the aromatic C­(sp2)–H bond is more likely to be activated than C­(sp3)–H bond under the same conditions. As representatives of cyclometalated complexes containing an M–C­(sp2) bond, cycloiridated complex 1 and cyclorhodated complex 3 reacted with DMAD to afford corresponding seven-membered cyclometalated complexes 13 and 14 via 1,2-insertion of alkyne into M–C bond. However, the reaction of 1 with diphenylacetylene or phenylacetylene resulted in five-membered and six-membered doubly cycloiridated complexes 15 or 16, the formation of which presumably went through the vinylidene rearrangement of alkynes followed by 1,1-insertion; while the reaction of 3 with diphenylacetylene or phenylacetylene mainly gave normal seven-membered cyclorhodated complexes 17 or 18 by 1,2-insertion. For two representatives of cyclometalated complexes comprising an M–C­(sp3) bond, cycloiridated complex 4 and cyclorhodated complex 6 reacted with DMAD to form corresponding seven-membered cyclometalated complexes 20 and 21 by 1,2-insertion. Interestingly, the reactions of 4 and 6 with phenylacetylene generated six-membered metallacycle complexes 22 and 23, and a plausible formation pathway is the similar 1,1-insertion of vinylidene ligand into the M–C bond followed by the isomerization of the C–C double bond. Molecular structures of five-membered cyclometalated complexes 4 and 5 and insertion products 13, 15–19, 21, and 22 were determined by X-ray diffraction.

Reactions of naphthyl‐ and o‐methylphenyl‐substituted phosphines with [RuCl2(p‐cymene)]2 resulted in the corresponding phosphine‐substituted ruthenium dichlorides (1a,b and 3). When the reactions of aryl‐substituted phosphines or phosphinites with [RuCl2(p‐cymene)]2 are carried out in the presence of sodium acetate, aryl‐substituted phosphines or phosphinites are cyclometalated to give the corresponding five‐membered metallacycle complexes (2a,b and 4–6) through the intramolecular activation of a C(sp2)–H or C(sp3)–H bond. Competition reactions indicate that the aromatic C(sp2)–H bond is more likely to be activated than the C(sp3)–H bond under the same conditions, and that a five‐membered ring is formed in preference to a six‐membered ring. The chemical reactivity of 2a,b, two representatives of cycloruthenated complexes, were explored, including conversion of 1a,b to 2a,b, a substitution reaction of the η6‐arene ligand in 2a, synthesis of a bis(phosphine) complex starting from 2b, and reaction of 2a with diphenylacetylene. Besides, their catalytic activity on the reduction of ketones by transfer hydrogenation was also tested. The molecular structures of nine compounds, 1b, 2a, and 4–10, were determined by single‐crystal X‐ray diffraction.

Several five-membered cyclometalated rhenium complexes (1–5) were synthesized, and their photocatalytic activity on direct arylation of arenes with aryl halides was examined.

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