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.

Insertion reactions of aromatic alkynes into the Ir–C bond of six-membered cycloiridated complexes formed various novel products via different insertion modes.

Reactions of two dinaphthyl phosphines with [Cp*IrCl 2 ] 2 have been carried out. In the case of di(α-naphthyl)phenylphosphine ( 1a ), a simple P-coordinated neutral adduct 2a is obtained. However, tert -butyldi(α-naphthyl)phenylphosphine ( 1b ) is cyclometalated to form [Cp*IrCl(P^C)] ( 3b ). Complexes 2a and 3a undergo further cyclometalation to give the corresponding double cyclometalated complexes [Cp*Ir(C^P^C)] ( 4a , b ) upon heating. In the presence of sodium acetate, reactions of 1a , b with [Cp*IrCl 2 ] 2 directly afford the final double cyclometalated complexes ( 4a , b ). In the absence of acetate, [Cp*RhCl 2 ] 2 shows no reaction with 1a , b , whereas with acetate the reactions form the corresponding single cyclometalated complexes [Cp*RhCl(P^C)] ( 5a , b ), which react with t BuOK to form the corresponding rhodium hydride complexes ( 6a , b ). Treatment of 4a with CuCl 2 or I 2 leads to opening of two Ir–C σ bonds to yield the corresponding P-coordinated iridium dihalide ( 7 or 8 ) by means of an intramolecular C–C coupling reaction. A new chiral phosphine ( 11 ) is formed by the ligand-exchange reaction of 8 with PMe 3 . Reactions of the single cycloiridated complex 3b with terminal aromatic alkynes result in the corresponding five- and six-membered doubly cycloiridated complex 12 and/or η 2 -alkene coordinated complexes 13–15 ; the latter discloses that the electronic effect of terminal alkynes affects the regioselectivity. While the single cyclorhodated complex 5b reacts with terminal aromatic alkynes to form the corresponding six-membered cyclometalated complexes 16a–c by vinylidene rearrangement/1,1-insertion. Plausible pathways for formation of insertion products 13–16 were proposed. Molecular structures of twelve new complexes were determined by 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.