Tetrasilacyclobutadiene and Cyclobutadiene Tricarbonylruthenium Complexes: [η4-(tBu2MeSi)4Si4]Ru(CO)3 and [η4-(Me3Si)4C4]Ru(CO)3

The novel ruthenium tricarbonyl complexes (eta(4)-tetrasilacyclobutadiene)tricarbonyl ruthenium [eta(4)-((Bu2MeSi)-Bu-t)(4)Si-4]Ru(CO)(3) 2 and (eta(4)-cyclobutadiene)tricarbonylruthenium and [eta(4)-(Me3Si)(4)C-4]Ru(CO)(3) 4 were synthesized by the reaction of either the dipotassium salt of a tetras i lacyc lobutadi ene dianion derivative [((Bu2MeSi)-Bu-t)(4)Si-4](2-)center dot 2K(+) 1 or the dilithium salt of a cyclobutadiene dianion derivative [(Me3Si)(4)C-4](2-)center dot 2Li(+) 3 with [Ru(CO)(3)Cl-2](2). The spectral and structural characteristics of both 2 and 4 were compared with each other to reveal the general tendencies of the influence of the nature of skeletal atoms and transition metal on the geometry of the four-membered ring ligand and its electronic properties.