Borane-Bridged Ruthenium Complex Bearing a PNP Ligand: Synthesis and Structural Characterization

Xu, Yaqian; Rettenmeier, Christoph; Plundrich, Gudrun T.; Wadepohl, Hubert; Enders, Markus; Gade, Lutz H.

doi:10.1021/acs.organomet.5b00699

Cited by 24 publications

(21 citation statements)

References 45 publications

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“…The complexes containing similar bridging R–BH 3 ···Ru interactions have been reported to exhibit dynamic (B H 3 ···Ru signals at δ = +3 to −4 ppm) or static (bridging B– H ···Ru signals at δ = −6 to −14 ppm) behavior in the 1 H NMR spectra at room temperature. 19 Complex 7 is a rare example of a carborane cluster with an exohedral B–B bond to a simple borane, and it is the first example of the regioselective formation of such a bond under metal-promoted conditions. 20 This compound may also be considered as a snapshot of a probable intermediate in transition-metal-catalyzed synthesis of diboranes, which is an increasingly important area of organometallic research due to the rise to prominence of diborane reagents for borylation chemistry.…”

Section: Resultsmentioning

confidence: 99%

(BB)-Carboryne Complex of Ruthenium: Synthesis by Double B–H Activation at a Single Metal Center

et al. 2016

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The first example of a transition metal (BB)-carboryne complex containing two boron atoms of the icosahedral cage connected to a single exohedral metal center (POBBOP)Ru(CO)2 (POBBOP = 1,7-OP(i-Pr)2-2,6-dehydro-m-carborane) was synthesized by double B–H activation within the strained m-carboranyl pincer framework. Theoretical calculations revealed that the unique three-membered (BB)>Ru metalacycle is formed by two bent B–Ru σ-bonds with the concomitant increase of the bond order between the two metalated boron atoms. The reactivity of the highly strained electron-rich (BB)-carboryne fragment with small molecules was probed by reactions with electrophiles. The carboryne–carboranyl transformations reported herein represent a new mode of cooperative metal–ligand reactivity of boron-based complexes.

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Section: Resultsmentioning

confidence: 99%

(BB)-Carboryne Complex of Ruthenium: Synthesis by Double B–H Activation at a Single Metal Center

et al. 2016

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“…30 Addition of NaBH 4 to 2 in THF resulted in a color change from yellow to orange and eventually green upon workup and extraction with Et 2 O. Crystallization yielded dark green prisms from concentrated Et 2 O/pentane solutions at −25 °C that revealed that the second nitrogen in 2 had indeed been deprotonated as desired, but the reaction unexpectedly led to the isolation of N-capped, borane-bridged hydride Ru[(μ-H)BH 2 ]( Me SNNS Me )(PPh 3 ) (5) (Figure 5). Langer, Gade, and Trincado and Gruẗzmacher separately reported this type of MLC BH 3 binding across tricoordinate N-centered ligands with Fe, 41 Ru, 42 and Rh, 43 respectively. MLC binding of BH 3 has also been observed across a Ru−thiolate bond involving a tetradentate S 2 N 2 ligand with an ethylenediamine backbone and thiolate groups instead of thioethers.…”

Section: ■ Introductionmentioning

confidence: 91%

Ru(II) Complexes with a Chemical and Redox-Active S₂N₂ Ligand: Structures, Electrochemistry, and Metal–Ligand Cooperativity

et al. 2017

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Here we describe the synthesis, structures, and reactivity of Ru complexes containing a triaryl, redox-active S2N2 ligand derived from o-phenylenediamine and thioanisole subunits. The coordination chemistry of N,N′-bis[2-(methylthio)phenyl]-1,2-diaminobenzene [H2(MeSNNSMe)] was established by treating RuCl2(PPh3)3 with H2(MeSNNSMe) to yield {Ru[H2(MeSNNSMe)]Cl(PPh3)}Cl (1). Coordinated H2(MeSNNSMe) was sequentially deprotonated to form Ru[H(MeSNNSMe)]Cl(PPh3) (2) followed by the five-coordinate, square pyramidal complex Ru(MeSNNSMe)(PPh3) (3). Single-crystal X-ray diffraction (XRD) studies revealed that the ligand structurally rearranged around the metal at each deprotonation step to conjugate the adjacent aryl groups with the o-phenylenediamine backbone. Deprotonation of 2 with NaBH4 or treatment of 3 with BH3·tetrahydrofuran (THF) yielded Ru[(μ-H)BH2](MeSNNSMe)(PPh3) (5) with BH3 bound across a Ru–N bond in a metal–ligand cooperative fashion. The cyclic voltammogram of 3 in THF revealed three redox events consistent with one-electron oxidations and reductions of the o-phenylenediamine backbone and the metal (Ru3+/Ru2+). Reactions of 3 with CO, HBF4, and benzoic acid yielded the new complexes Ru(MeSNNSMe)(CO)(PPh3), {Ru[H(MeSNNSMe)](PPh3)(THF)}BF4, and Ru[H(MeSNNSMe)](PPh3)(PhCO2), indicating broader suitability for small molecule binding and reactivity studies. Subsequent nuclear magnetic resonance spectroscopy, infrared spectroscopy, and mass spectrometry data are reported in addition to molecular structures obtained from single-crystal XRD studies.

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“…A few reactions at the nitrogen atom of the central N ‐heterocycle, however, have been reported in addition to the N–N bond formation in CbzC ( i Pr PNP)‐coordinated zirconium complexes, which has been discussed above (Scheme ). The crystallographically characterized CbzC ( Ph PNP)‐ruthenium complex 92 , for example, was found to exhibit a four‐membered N‐B‐H‐Ru metallacycle (Scheme ) . This structural motif was also found in a manganese complex bearing the acridane‐based PNP ligand scaffold (cf.…”

Section: Pnp Pincers and Their Reactivity Patternsmentioning

confidence: 98%

“…Scheme ), this procedure has not found widespread use, although exceptions are known. For CbzC ( Ph PNP)H, for example, the NH‐containing ruthenium complex 5 has been isolated and in turn converted into the pincer derivative 6 via reaction with KO t Bu (see Scheme ) . Intermediates such as 5 may also play a role in cases, where bases are mixed with the ligand and the metal precursor at the same time (as in the synthesis of CbzC ( i PrPNP)Cu from CbzC ( i PrPNP)H, LiO t Bu and CuCl or Pyr ( i PrPNP)Ir(cod) from Pyr ( i PrPNP)H, [(cod)Ir( µ ‐Cl] 2 and KO t Bu).…”

Section: Preparation Of Pnp Pincer Complexesmentioning

confidence: 99%

Phosphines and N‐Heterocycles Joining Forces: an Emerging Structural Motif in PNP‐Pincer Chemistry

2020

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Aminodiphosphines and their monoanionic amido derivatives are among the most widely used tridentate ligands. A good share of these ligands, in particular the ones that are based on a rigid N‐heterocyclic core, is predisposed to coordinate in a meridional fashion. Negatively charged derivatives of these meridionally coordinating N‐heterocyclic ligands satisfy all the criteria for PNP pincer scaffolds. Herein, these ligands and their coordination chemistry is reviewed from the perspective of coordination chemistry. For our discussion, ligands containing a protonated N‐heterocycle (e.g. pyrrole‐ or carbazole‐based PNP scaffolds) are to be distinguished from their counterparts that do not contain such an NH‐functionality (e.g. pyridine‐ or triazine‐based PNP scaffolds). Different synthetic methodologies for the preparation of PNP pincer complexes are presented and shown to often depend on the presence or absence of the aforementioned NH‐proton. The different reactivity patterns of the resulting complexes are sub‐divided into two categories, namely into metal‐centered reactions and reactions that result in a chemical transformation at the metal and the ligand. The latter represent ligand‐cooperative transformations, which often play a key role in catalysis, and are showcased by discussing selected applications in catalysis. It will become evident in this review that this relatively young research field is still emerging and far from reaching maturity. Finally, a brief overview on ligand/metal combinations that have not been explored to date is provided, to stimulate future research on PNP pincers featuring a central N‐heterocycle.

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Borane-Bridged Ruthenium Complex Bearing a PNP Ligand: Synthesis and Structural Characterization

Abstract: Reaction of the precursor complex [RuHCl(CO)(PPh 3 ) 3 ] with the PNP

Cited by 24 publications

References 45 publications

(BB)-Carboryne Complex of Ruthenium: Synthesis by Double B–H Activation at a Single Metal Center

(BB)-Carboryne Complex of Ruthenium: Synthesis by Double B–H Activation at a Single Metal Center

Ru(II) Complexes with a Chemical and Redox-Active S₂N₂ Ligand: Structures, Electrochemistry, and Metal–Ligand Cooperativity

Phosphines and N‐Heterocycles Joining Forces: an Emerging Structural Motif in PNP‐Pincer Chemistry

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Borane-Bridged Ruthenium Complex Bearing a PNP Ligand: Synthesis and Structural Characterization

Abstract: Reaction of the precursor complex [RuHCl(CO)(PPh 3 ) 3 ] with the PNP

Cited by 24 publications

References 45 publications

(BB)-Carboryne Complex of Ruthenium: Synthesis by Double B–H Activation at a Single Metal Center

(BB)-Carboryne Complex of Ruthenium: Synthesis by Double B–H Activation at a Single Metal Center

Ru(II) Complexes with a Chemical and Redox-Active S2N2 Ligand: Structures, Electrochemistry, and Metal–Ligand Cooperativity

Phosphines and N‐Heterocycles Joining Forces: an Emerging Structural Motif in PNP‐Pincer Chemistry

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Ru(II) Complexes with a Chemical and Redox-Active S₂N₂ Ligand: Structures, Electrochemistry, and Metal–Ligand Cooperativity