In the last decades, metal ligand cooperativity has intensively been used as tool in homogeneous catalysis for the development of potent catalysts for a variety of applications, above all hydrogenation and transfer hydrogenation reactions. Herein, we report on the synthesis of iminophosphinoyl-tethered ruthenium carbene complexes and their use in the activation of dihydrogen and the catalytic transfer hydrogenation of p-fluoroacetophenone. Variation of the N-substituent to an electron-withdrawing pnitrophenyl group enabled the reversible activation of elemental hydrogen via a 1,2-addition across the metal carbon double bond both in solution and in solid state. In comparison to the thiophosphinoyl-tethered carbene complex the presented iminophosphinoyl systems showed a considerably increased catalytic activity in transfer hydrogenation reactions, thus highlighting the tunability of the cooperative behavior of nucleophilic carbene complexes.