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Giner Planas J, Hampel F, Gladysz JA: Generation and reactions of ruthenium phosphido complexes [(eta5-C5H5) Ru (PR'3) 2 (PR2)]: remarkably high phosphorus basicities and applications as ligands for palladium-catalyzed Suzuki cross-coupling reactions. Chemistry. 2005 Feb 18;11(5):1402-16.
Reactions of [(eta5-C5H5) Ru (PR'3) 2 (Cl)] with NaBAr (F) [BAr (F)-=B{3,5-[C6H3 (CF3) 2]}4-; PR'3=PEt3 or 1/2Et2PCH2CH2PEt2) (depe)] and PR2H (R=Ph, a; tBu, b; Cy, c) in C6H5F, or of related cationic Ru (N2) complexes with PR2H in C6H5F, gave the secondary phosphine complexes [(eta5-C5H5) Ru (PR'3) 2 (PR2H)]+ BAr (F)- (PR'3=PEt3, 3 a-c; 1/2depe, 4 a,b) in 65-91 % yields. Additions of tBuOK (3 a, 4 a; [D6] acetone) or NaN (SiMe3) 2 (3 b,c, 4 b; [D8] THF) gave the title complexes [(eta5-C5H5) Ru (PEt3) 2 (PR2)] (5 a-c) and [(eta5-C5H5) Ru (depe)(PR2)] (6 a,b) in high spectroscopic yields. These complexes were rapidly oxidized in air; with 5 a, [(eta5-C5H5) Ru (PEt3) 2{P (=O) Ph2}] was isolated (> 99 %). The reaction of 5 a and elemental selenium yielded [(eta5-C5H5) Ru (PEt3) 2{P (=Se) Ph2}] (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 [(eta5-C5H5) Re (NO)(PPh3)(PPh2)], and that 6 b is more basic than PtBu3 and P (iPrNCH2CH2) 3N. The latter is one of the most basic trivalent phosphorus compounds [pK (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 PtBu3; 5 a, with a less bulky and electron-rich PR2 moiety, gave a less active catalyst. The reaction of 5 a and [(eta3-C3H5) Pd (NCPh) 2]+ BF4- gave the bridging phosphido complex [(eta5-C5H5) Ru (PEt3) 2 (PPh2) Pd (NCPh)(eta3-C3H5)]+ 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. |
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