Generation and Reactions of Ruthenium Phosphido Complexes [(η 5 ‐C 5 H 5 )Ru(PR′ 3 ) 2 (PR 2 )]: Remarkably High Phosphorus Basicities and Applications as Ligands for Palladium‐Catalyzed Suzuki Cross‐Coupling Reactions

Reactions of [(η 5 ‐C 5 H 5 )Ru(PR′ 3 ) 2 (Cl)] with NaBAr F [BAr F − =B{3,5‐[C 6 H 3 (CF 3 ) 2 ]} 4 − ; PR′ 3 =PEt 3 or 1/2Et 2 PCH 2 CH 2 PEt 2 (depe)] and PR 2 H (R=Ph, a ; t Bu, b ; Cy, c ) in C 6 H 5 F, or of related cationic Ru(N 2 ) complexes with PR 2 H in C 6 H 5 F, gave the secondary phosphine complexes [(η 5 ‐C 5 H 5 )Ru(PR′ 3 ) 2 (PR 2 H)] + BAr F − (PR′ 3 =PEt 3 , 3 a – c ; 1/2depe, 4 a , b ) in 65–91 % yields. Additions of t BuOK ( 3 a , 4 a ; [D 6 ]acetone) or NaN(SiMe 3 ) 2 ( 3 b , c , 4 b ; [D 8 ]THF) gave the title complexes [(η 5 ‐C 5 H 5 )Ru(PEt 3 ) 2 (PR 2 )] ( 5 a – c ) and [(η 5 ‐C 5 H 5 )Ru(depe)(PR 2 )] ( 6 a , b ) in high spectroscopic yields. These complexes were rapidly oxidized in air; with 5 a , [(η 5 ‐C 5 H 5 )Ru(PEt 3 ) 2 {P(O)Ph 2 }] was isolated (>99 %). The reaction of 5 a and elemental selenium yielded [(η 5 ‐C 5 H 5 )Ru(PEt 3 ) 2 {P(Se)Ph 2 }] (70 %); selenides from 5 c and 6 a were characterized in situ. Competitive deprotonation reactions showed that 5 a is more basic than the rhenium analog [(η 5 ‐C 5 H 5 )Re(NO)(PPh 3 )(PPh 2 )], and that 6 b is more basic than P t Bu 3 and P( i PrNCH 2 CH 2 ) 3 N. The latter is one of the most basic trivalent phosphorus compounds [p K a (acetonitrile) 33.6]. Complexes 5 a – c and 6 b are effective ligands for Pd(OAc) 2 ‐catalyzed Suzuki coupling reactions: 6 b gave a catalyst nearly as active as the benchmark organophosphine P t Bu 3 ; 5 a , with a less bulky and electron‐rich PR 2 moiety, gave a less active catalyst. The reaction of 5 a and [(η 3 ‐C 3 H 5 )Pd(NCPh) 2 ] +  BF 4 − gave the bridging phosphido complex [(η 5 ‐C 5 H 5 )Ru(PEt 3 ) 2 (PPh 2 )Pd(NCPh)(η 3 ‐C 3 H 5 )] +  BAr F − in approximately 90 % purity. The crystal structure of 4 a is described, as well as substitution reactions of 3 b and 4 b .