Reactions of the Lithiated Diphosphine t Bu 2 P–P(SiMe 3 )Li with [(η 6 ‐C 6 H 6 )RuCl 2 ] 2 in the Presence of Tertiary Phosphines

t Bu 2 P–P(SiMe 3 )Li reacted with [(η 6 ‐C 6 H 6 )RuCl 2 ] 2 at –40 °C in the presence of PR 3 (PR 3 = PEt 3 , PEt 2 Ph, PEtPh 2 ) by the nucleophilic addition of the t Bu 2 P–P(SiMe 3 ) moiety to the benzene ring to yield solely the complexes [(R 3 P) 2 Ru(Cl){η 5 ‐C 6 H 6 (Me 3 SiP–P t Bu 2 )}] ( 1 ). These products decomposed slowly at ambient temperature to yield benzene, Ru clusters, and small amounts of the dinuclear ruthenium complexes [{(R 3 P) 2 Ru} 2 (µ,η 2:2 ‐P 2 ) 2 Ru(PR 3 ) 2 ] ( Ru–Ru ) ( 6 ). Single‐crystal X‐ray diffraction studies of [(PhEt 2 P) 2 Ru(Cl){η 5 ‐C 6 H 6 (Me 3 SiP–P t Bu 2 )}] ( 1b ) and [(Ph 2 EtP) 2 Ru(Cl){η 5 ‐C 6 H 6 (Me 3 SiP–P t Bu 2 )}] ( 1c ) revealed that the addition of the t Bu 2 P–P(SiMe 3 ) group occurred through an exo pathway. Complex 6a (R = Et) displays a planar rectangular P 4 system consisting of two P 2 units and a Ru–Ru distance that lies in the range of a single bond.