The Thermolysis of Ru 3 (CO) 12 with Carboxylic Acids Revisited: Stepwise Assembly of Ru 2 to Ru 6 Cluster Frameworks

Thermolysis of Ru 3 (CO) 12 with carboxylic acids directly accessed a large variety of low valence ruthenium carbonyl complexs. Under the conditions of the reaction firstly reported by J. Lewis, 3 equivalents of acids were employed to assembly sawhorse‐type dirutheniumtetra carbonyl complex. Six Ru 3 ‐Ru 6 ruthenium clusters were unexpectedly isolated in the reaction of Ru 3 (CO) 12 with 1 equivalent of carboxylic acids under thermal condition. The reaction of Ru 3 (CO) 12 with ten kind of carboxylic acids were systematically investigated. The reactions of Ru 3 (CO) 12 with non‐coordinative carboxylic acids afforded β‐H 2 Ru 4 (CO) 13 ( 2 ), Ru 6 (μ 6 ‐C)(μ‐CO)(CO) 16 ( 3 ) and then to Ru 6 (μ 6 ‐C)(μ‐CO)(CO) 13 (η 6 ‐C 6 H 5 CH 3 ) ( 4 ), respectively. The further experiments indicated that the formation of 3 was attributed to the assembly of tetraruthenium carbonyl dihydrid 2 with polymeric sawhorse diruthenium intermediate [Ru 2 (CO) 4 (OOR) 2 ] n (R= alkyl, aryl). The thermolysis of phenylpropiolic acid with Ru 3 (CO) 12 unveiled an alternative pathway to access Ru 6 skeleton. The triruthenium cluster [(μ‐H)Ru 3 (CO) 9 (μ 3 ‐η 2 ‐(⊥)‐C≡CC 6 H 5 )] ( 5 ) and butterfly tetraruthenium compound Ru 4 (CO) 12 (HC≡CC 6 H 5 ) ( 6 ) were identified as the key intermediates in the construction of compound  3 .