Mononuclear Rh(II) PNP-Type Complexes. Structure and Reactivity

Feller, Moran; Ben-Ari, Eyal; Gupta, Tarkeshwar; Shimon, Linda J. W.; Leitus, Gregory; Diskin‐Posner, Yael; Weiner, Lev; Milstein, David

doi:10.1021/ic701044b

Cited by 75 publications

(95 citation statements)

References 44 publications

(65 reference statements)

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“…Notably, no "macrocycle effect" is apparent on comparison of the carbenic and carbonyl 13 ( 1 J RhC = 70 Hz) and ν(CO) 1982 cm -1 in solution, and a Rh-C distance of 1.818(5) Å in the solid-state. 25 Figure 1: Solid-state structures of 1a/1a*. Thermal ellipsoids drawn at the 50% (left, symmetrical; 1a) and 30% (right, asymmetrical; 1a*) probability levels; minor disordered components and anions are omitted for clarity.…”

Section: Characterisationmentioning

confidence: 99%

Synthesis and Reactivity of NHC-Based Rhodium Macrocycles

Andrew

Chaplin

2014

Inorg. Chem.

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Using a general synthetic procedure employing readily accessed terminal alkene functionalised pro-ligands and macrocyclisation by ring-closing olefin metathesis, rhodium carbonyl complexes have been prepared that contain lutidine-(1a; n = 1) and pyridine-(1b; n = 0) derived tridentate CNC macrocycles with dodecamethylene spacers. In solution 1a shows temperature invariant time averaged C 2 symmetry by 1 H NMR spectroscopy (CD 2 Cl 2 , 500 MHz), while in the solid-state two polymorphs can be obtained showing different conformations of the alkyl spacer about the metal-carbonyl bond (asymmetric and symmetric). In contrast, time-averaged motion of alkyl spacer in 1b can be halted by cooling below 225 K (CD 2 Cl 2 , 500 MHz) and the complex crystallises as a dimer with an interesting unsupported Rh···Rh bonding interaction (3.2758(6) Å). Oxidative addition reactions of 1a and 1b, using MeI and PhICl 2 , have been studied in situ by 1 H NMR spectroscopy, although pure Rh(III) adducts can ultimately only be isolated with the pyridine-based macrocyclic ligand. The lutidine backbone of 1a can be deprotonated by addition of K[N(SiMe 3 ) 2 ] and the resulting neutral dearomatised complex (5) has been fully characterised in solution, by variable temperature 1 H NMR spectroscopy, and in the solid-state, by X-ray diffraction.

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Section: Characterisationmentioning

confidence: 99%

Synthesis and Reactivity of NHC-Based Rhodium Macrocycles

Andrew

Chaplin

2014

Inorg. Chem.

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“…[68] Depending on the counterion of the Ag salt, either direct oxidation of the ubiquitous complex [RhCl(12 tBu )] (32) to complex 34, or a two-step reaction to Rh I derivative 33 and subsequent oxidation to 35 is observed (Scheme 16). The square planar, paramagnetic mononuclear Rh II species 34 showed subtle but significant alterations in, for example, the Rh À P and Rh À Cl bond lengths, which are attributable to the change in the metal oxidation state.…”

Section: Rhodiummentioning

confidence: 99%

Neutral Tridentate PNP Ligands and Their Hybrid Analogues: Versatile Non‐Innocent Scaffolds for Homogeneous Catalysis

Vlugt¹,

Reek²

2009

Angew Chem Int Ed

420

145

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Ligands in coordination chemistry and homogeneous catalysis are traditionally "static" spectators that do not actively participate in the catalytic cycle. However, such classic systems do not provide additional "handles" that could facilitate or trigger alternative productive reaction pathways. Recent advances in the use of novel nitrogen-centered pincer systems have unveiled interesting opportunities for cooperative catalysis. The chemistry of pyridine-derived, neutral ligands is discussed, with a specific focus on their non-innocent behavior and potential as facilitators for metal-mediated organic transformations. This overview should provide inspiration and an incentive to incorporate non-innocent ligands and their metal complexes within old and new homogeneously catalyzed reactions.

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“…Single crystal X-ray diffraction was used to characterize 3 (Figure 4), indicating a pseudotetrahedral geometry around iron 45,46 with angles in the 98.91(4)−122. 62(3)°range. The distortion observed (angles smaller or larger than the ideal value, 104.5°) may be attributed to the relative rigidity of the tPCHCHP backbone.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…1 H NMR (500 MHz, C 6 D 6 ) δ: 0.11 (ν 1/2 = 204.99 Hz, 6H, CH(CH 3 ) 2 ), 2.87 (ν 1/2 = 107. 62 Hz, 6H, CH(CH 3 ) 2 ), 5.30 (ν 1/2 = 440. 72 Hz, 12H, CH(CH 3 ) 2 ), 6.83 (ν 1/2 = 491.97 Hz, 8H, ArH), 11.66 (ν 1/2 = 645.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Coordination of a Hemilabile Pincer Ligand with an Olefinic Backbone to Mid-to-Late Transition Metals

Barrett

Iluc

2014

Inorg. Chem.

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The coordination chemistry of a neutral tPCH═CHP pincer (tPCH═CHP = 2,2'-bis(di-iso-propylphosphino)-trans-stilbene) with metals that form stable complexes in the +1 oxidation state was studied and (tPCH═CHP)CoCl, (tPCH═CHP)CoCl(CO), (tPCH═CHP)RhCl, (tPCH═CHP)Cu(OTf), [(tPCH═CHP)Cu][PF6], and [(tPCH═CHP)Ag][PF6] were synthesized and characterized. In order to determine whether the coordination mode is dependent on the oxidation state of the metal, some +2 metal complexes, (tPCH═CHP)CoCl2 and (tPCH═CHP)FeBr2, were also investigated. The coordination of the olefinic backbone is not observed in (tPCH═CHP)FeBr2, (tPCH═CHP)CoCl2, (tPCH═CHP)Cu(OTf), or [(tPCH═CHP)Ag][PF6], but η(2)-coordination is present in [(tPCH═CHP)CoCl][BAr(F)4], [(tPCH═CHP)FeBr][BAr(F)4], (tPCH═CHP)CoCl, (tPCH═CHP)CoCl(CO), (tPCH═CHP)RhCl, and [(tPCH═CHP)Cu][PF6]. Cobalt(II), iron(II), and copper(I) formed complexes with the ligand in both coordination modes. All metal complexes were characterized by multinuclei NMR spectroscopy, X-ray crystallography, and elemental analysis.

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Mononuclear Rh(II) PNP-Type Complexes. Structure and Reactivity

Cited by 75 publications

References 44 publications

Synthesis and Reactivity of NHC-Based Rhodium Macrocycles

Synthesis and Reactivity of NHC-Based Rhodium Macrocycles

Neutral Tridentate PNP Ligands and Their Hybrid Analogues: Versatile Non‐Innocent Scaffolds for Homogeneous Catalysis

Coordination of a Hemilabile Pincer Ligand with an Olefinic Backbone to Mid-to-Late Transition Metals

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