Analogies between Metallaboratranes, Triboronates, and Boron Pincer Ligand Complexes

Abstract

The reaction of [RuRCl(CO)(PPh 3 ) 2 ] (R = C 6 H 5 , CHdCHPh) with the Yamashita-Nozaki ligand C 6 H 4 {N(CH 2 PPh 2 )} 2 BH (dppBH) results in facile elimination of benzene or styrene and formation of the ruthenium [PBP]pincer complex [Ru{κ 3 B,P,P 0 -dppB)Cl(CO)(PPh 3 )] via a stepwise sequence that recalls the formation of the ruthenaboratrane [Ru(CO)(PPh 3 ){B(mt) 3 }] (mt = methimazolyl) from [RuRCl-(CO)(PPh 3 ) 2 ] and Na[HB(mt) 3 ]. This analogy is explored herein, including observations regarding notionally similar processes for triboronate ligands. Thus, while the major product of the reaction ofalso obtained, consistent with alcoholic transfer hydrogenation of the putative complex [B 3 H 7 Ru(CO)(PPh 3 ) 2 ]. a Legend: (i) K[H 2 B(mt) 2 ]; 6 (ii) Tl[B 3 H 8 ]; 8 (iii) [Me 4 N][C 2 B 9 H 12 ]; 9 (iv) C 6 H 4 N 2 (CH 2 PPh 2 ) 2 BH (dppBH).10a

Toward a comprehensive definition of oxidation state (IUPAC Technical Report)

“…The supported TM → Z complexes include bis-or tris-(methimazolyl)boranes and phosphine boranes, with main contributions from the groups of Hill [324], Parkin [325], Bourissou [154], and more recently of Mösch-Zanetti [326] and Nakazawa [327]. Contemporary examples of unsupported structurally characterized TM → Z complexes are chronicled in a remarkable series of articles by Braunschweig and co-workers utilizing the electron-rich, two-coordinate Pt(PCy 3 ) 2 (Cy = cyclohexyl) or Pt(PCy 3 )(IMes) [IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazole-2-ylidene] fragments.…”

Recent Developments in the Coordination Chemistry of Multidentate Ligands Featuring a Boron Moiety

“…The ligand precursor 47 was converted to the first boryl-centered PBP iridium complex 48 by reaction with [{IrA C H T U N G T R E N N U N G (cod)Cl} 2 ] (cod = cyclooctadiene) by oxidative B À H addition. After this initial report, both rhodium [60] and platinum [61] PBP complexes were reported by the same group, and ruthenium complexes involving the same PBP ligand were reported by Hill et al [62] Iridium complex 48 reacted with CO to afford the monocarbonyl complex 49, in which Cl is located in the position trans to the boryl ligand. An increased Ir À Cl distance of 2.5307 for 49, relative to that of benzene-based PCP complex 50 (2.475 ), was observed, which indicates a stronger s-donating ability of the PBP ligand compared to the PCP ligand.…”

The Organometallic Chemistry of Boron-Containing Pincer Ligands based on Diazaboroles and Carboranes

“…69 Reaction of 1b with (Ph 3 P) 2 Ru(Cl)(Ph)(CO) smoothly furnished (PBP)Ru(Cl)(CO)(PPh 3 ) (57) with extrusion of C 6 H 6 . The solid-state structure of 57 was determined by single-crystal Xray diffraction analysis and revealed Ru had a hexacoordinate structure.…”

“…Teixidor reported the complexation of a tridentate nido-[7,8-C 2 B 9 H 12 ]-based ligand that contains two thioether moieties (69) and RhCl 3 to afford the corresponding bis adduct 70 as an anionic complex (Scheme 23, top). 76 Therein, one of the two C 2 B 9 units coordinates to Rh in a tridentate fashion via two sulfur atoms and one boron atom, while the other C 2 B 9 unit coordinates in a bidentate manner via the two sulfur atoms.…”