Protonation of metal-metal bonds in nitrosyl-bridged diruthenium complexes

The addition reaction of a proton towards the nitrosyl-bridged diruthenium complexes [Ru-2(CO)(4)(mu-NO)(mu-(PBu2)-Bu-t)(mu-(PP)-P-boolean AND)] ((PP)-P-boolean AND = Me2PCH2PMe2, dmpm, 1b; (PP)-P-boolean AND = Ph2PC(=CH2)PPh2, dppen, 1c; (PP)-P-boolean AND = Ph-2-PN(H)PPh2, dppa, 1d) has been investigated. The species 1b-d exhibit an enhanced metal basicity and react spontaneously with a proton (from HBF4) in diethyl ether to afford the corresponding oxidative addition products [Ru-2(CO)(4)(mu-NO)(mu-H)(mu-(PBu2)-Bu-t)(mu-(PP)-P-boolean AND)]BF4 (2b-d) in good yields. The molecular structures of 2b-d were confirmed by X-ray diffraction studies revealing a shortening of the metal-metal bond upon protonation in each case. (C) 2013 Elsevier Ltd. All rights reserved.