Homodinuclear Rare‐Earth Metal Complexes as Efficient Precatalysts for the Stereoselective Hydrosilylation of Inactivated Internal Diaryl Alkynes with (Aryl)(vinyl)silanes or Diphenylsilane

Comprehensive Summary The hydrosilylation of internal alkynes is an important protocol for the synthesis of trisubstitued alkenyl silanes, which are very useful building blocks in synthetic chemistry and materials science. However, the hydrosilylation of inactivated internal diaryl alkynes with (aryl)(vinyl)silanes or diphenylsilane faces challenges of the lack of active catalyst and difficulty in controlling stereoselectivity. Herein, the bridged pincer homodinuclear rare‐earth metal complexes [ μ ‐ η 2 ‐{ κ 3 OCO ‐1‐(2‐C 4 H 7 OCH 2 )‐3‐(Ph 2 P(O)CH)C 8 H 4 N}RE(CH 2 SiMe 3 )] 2 (RE = Lu( 1a ), Yb( 1b ), Er( 1c ), Y( 1d ), Dy( 1e ), Gd( 1f )), [ μ ‐ η 2 ‐{ κ 3 OCO ‐1‐MeOCH 2 CH 2 ‐3‐(Ph 2 P(O)CH)C 8 H 4 N}RE(CH 2 SiMe 3 )] 2 (RE = Lu( 2a ), Y( 2b )) and [ μ ‐ η 2 ‐{ κ 3 OCN ‐1‐(2‐C 5 H 4 N)‐3‐(Ph 2 P(O)CH)C 8 H 4 N}RE(CH 2 SiMe 3 )] 2 (RE = Lu( 3a ), Yb( 3b ), Er( 3c )) were synthesized. Meanwhile, the pincer mononuclear complexes κ 3 OCO ‐[1‐(2‐C 4 H 7 OCH 2 )‐3‐(Ph 2 P(O)CH 2 )C 8 H 4 N]Lu(CH 2 SiMe 3 ) 2 ( 1a' ), and κ 3 OCO ‐[1‐MeOCH 2 CH 2 ‐3‐ (Ph 2 P(O)CH 2 )C 8 H 4 N]Lu(CH 2 SiMe 3 ) 2 ( 2a' ) were prepared for comparison of their catalytic activities with the homodinuclear complexes. These homodinuclear complexes displayed high catalytic activity in the hydrosilylation of inactivated internal diaryl alkynes with RSiH 3 (R = C 6 H 5 ‐, 4‐CH 3 C 6 H 4 ‐, C 8 H 17 ‐, C 6 H 13 ‐), (aryl)(vinyl)silanes and diphenylsilane, affording the vinylsilane products in moderate to high yields with excellent stereoselectivity. Among the complexes surveyed, the homodinuclear complex 1d exhibited the highest activity. Moreover, the bis‐hydrosilylation of two different internal alkynes with RSiH 3 was also developed. Control experiments evidence supports that the synergistic interaction between the bimetallic centers in these complexes played a crucial role in their high efficiency demonstrated in the reaction.