Hydride and Dihydrogen Ruthenium Complexes of the Tripyrrolylphosphine Ligand

Abstract

The reactivity of the ruthenium(IV) trihydride complex Cp*RuH3(Ppyl3) (2), accommodating the π-accepting tripyrrolylphosphine (Ppyl3), has been studied with regard to substitution and protonation reactions. Substitution of two hydrides by excess Ppyl3 and CO leads to Cp*RuHL(Ppyl3) (L = Ppyl3, 3; L = CO, 4). The reaction with tBuNC leads first to the substitution of two hydrides by the ligand, but the reaction proceeds further to yield, through an unprecedented decyanation reaction, the cyano complex Cp*Ru(CN)(tBuNC)(Ppyl3) (6), which has been characterized by X-ray diffraction. Addition of HSiMe2Ph in refluxing toluene yields Cp*RuH2(SiMe2Ph)(Ppyl3) (7), a dihydridosilylruthenium(IV) complex that has been characterized by spectroscopic data and an X-ray crystal structure. Finally, protonation of 4 yields the dihydrogen complex [Cp*Ru(H2)(CO)(Ppyl3)](BF4) (8), which easily loses H2 in solution and displays a very short T 1 minimum, in agreement with a low electron density on the metal.

Direct Synthesis of a Bis(pyrazolyl)boratocopper(I) Complex: Synthesis and Characterization of [H2B(3,5-(CF3)2Pz)2]Cu(PPh3)2 Displaying an Unusual Coordination Mode for a Poly(pyrazolyl)borate Ligand

“…16 The structurally characterized ruthenium adduct [H 2 B(3,5-(CF 3 ) 2 -Pz) 2 ]RuH(COD) featuring type B coordination (Ru‚‚‚HB ) 1.97(3) Å) also shows similar infrared data for terminal and bridging B-H moieties (2555 cm -1 and 2128 and 2028 cm -1 ). 12 The room-temperature NMR data of [H 2 B(3,5-(CF 3 ) 2 Pz) 2 ]Cu-(PPh 3 ) 2 suggest fluxional behavior in solution as 1 H, 13 C, and 19 F NMR spectra show resonances attributable to equivalent pyrazolyl moieties.…”

“…However, the bond angle data clearly suggest this to be a very weak one. To our knowledge, [H 2 B(3,5-(CF 3 ) 2 Pz) 2 ]Cu(PPh 3 ) 2 represents the first structurally characterized bis(pyrazolyl)borate 12 Very recently, a tris(pyrazolyl)-borate adduct ([HB(4-Cl-3,5-(CH 3 ) 2 Pz) 3 ]Rh(CO)(PMePh 2 ) 2 ) featuring rare κ 2 N,H coordination has also been reported. 18 The main reason for unusual modes of coordination in these poly-(pyrazolyl)borate systems is believed to be steric in origin.…”

“…18 The main reason for unusual modes of coordination in these poly-(pyrazolyl)borate systems is believed to be steric in origin. 12,18,19 …”

Copper(I) complexes supported by a heavily fluorinated bis(pyrazolyl)borate: syntheses and characterization of [H2B(3,5-(CF3)2Pz)2]CuL (where L = PPh3, N CCH3, HC CPh, H2C CHPh) and {[H2B(3,5-(CF3)2Pz)2]Cu}2(1,5-COD)

“…Although these fluorinated ligands are relatively new compared to the non-fluorinated tris(pyrazolyl)borates, they have already been used very successfully to investigate a wide range of topics including catalytic C-H and C-Cl bond activation [26,28], oxidation chemistry, isolation of low valent gallium and indium compounds (e.g., 3), [13,20] models for intermediates in silver halide metathesis (e.g., 4) [16,21,22], and to stabilize labile or reactive species like metal-organoazide complexes (e.g., 5) [17], silver and gold carbonyl (e.g., 6) compounds [4,9,14], and copper and silver ethylene adducts [14,23]. Despite the interesting chemistry observed with fluorinated tris(pyrazolyl)borates, relatively little has been reported on the use of closely related bis(pyrazolyl)borates [11,12,19,24,34,38,45] 2 ]Cu complexes containing styrene, 1,5-cyclooctadiene (1,5-COD), phenylacetylene as well as the related copper(I) acetonitrile and triphenylphosphine adducts.…”

Zwitterionic Relatives of Cationic Platinum Group Metal Complexes: Applications in Stoichiometric and Catalytic σ‐Bond Activation

“…The convenient preparation of 16 and related rhodium zwitterions were reported subsequently, [78][79][80] as was the formation and spectroscopic characterization of the rhodium zwitterion 17 (Scheme 8). [81] In keeping with the phenylborate zwitterion 3, the crystallographically characterized complex 16 can be described as featuring a (dippe)Rh + moiety that is coordinated in an h 6 fashion to the bis(catecholato)borate anion (Bcat 2 À ).…”