Molybdenum Alkylidyne Complexes with Tripodal Silanolate Ligands: The Next Generation of Alkyne Metathesis Catalysts

Hillenbrand, Julius; Leutzsch, Markus; Fürstner, Alois

doi:10.1002/ange.201908571

Cited by 21 publications

(5 citation statements)

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“…20 − 23 The exclusive formation of 4 from one of the best available catalysts is therefore nonintuitive. 10 , 11 A veritable conundrum accrues when the behavior of the tungsten analogue 3 (R = 2,6-Me 2 C 6 H 3 -) is also taken into consideration, which furnished the canonical metallacyclobutadiene 5 on reaction with 3-hexyne. It took 1 week for the latter to transform into 6 by what represents a single “turnover”; complex 3 is hence catalytically incompetent.…”

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Productive Alkyne Metathesis with “Canopy Catalysts” Mandates Pseudorotation

et al. 2021

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Molybdenum alkylidyne complexes of the “canopy catalyst” series define new standards in the field of alkyne metathesis. The tripodal ligand framework lowers the symmetry of the metallacyclobutadiene complex formed by [2 + 2] cycloaddition with the substrate and imposes constraints onto the productive [2 + 2] cycloreversion; pseudorotation corrects this handicap and makes catalytic turnover possible. A combined spectroscopic, crystallographic, and computational study provides insights into this unorthodox mechanism and uncovers the role that metallatetrahedrane complexes play in certain cases.

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Productive Alkyne Metathesis with “Canopy Catalysts” Mandates Pseudorotation

et al. 2021

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“…A combined experimental and computational approach helps to interpret the now available shift data and in so doing provides insights into the electronic nature of these valuable catalysts. 28 − 30 …”

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Triple Resonance Experiments for the Rapid Detection of ¹⁰³Rh NMR Shifts: A Combined Experimental and Theoretical Study into Dirhodium and Bismuth–Rhodium Paddlewheel Complexes

et al. 2021

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A H(C)Rh triple resonance NMR experiment makes the rapid detection of 103 Rh chemical shifts possible, which were previously beyond reach. It served to analyze a series of dirhodium and bismuth–rhodium paddlewheel complexes of the utmost importance for metal–carbene chemistry. The excellent match between the experimental and computed 103 Rh shifts in combination with a detailed analysis of the pertinent shielding tensors forms a sound basis for a qualitative and quantitative interpretation of these otherwise (basically) inaccessible data. The observed trends clearly reflect the influence exerted by the equatorial ligands (carboxylate versus carboxamidate), the axial ligands (solvents), and the internal “metalloligand” (Rh versus Bi) on the electronic estate of the reactive Rh(II) center.

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“…[22][23][24][25][26] Hence, a tris-PN pro-ligand (H3 R L) based on a rigid triarylbenzene backbone was designed (Scheme 1A). Using a similar backbone, tris-alkoxide, -siloxide, and -carboxylate variants have been described, [27][28][29] and tris-phosphine precursors (Int1) bearing phenyl-or adamantyl substituents are readily prepared (Supporting Information). [30][31] However, attempts to convert Int1 to H3 R L via traditional routes, including the usage of Me3SiN3 6 or aminolysis of R3PCl2 derivatives 32 proved unsuccessful; even after prolonged heating, incomplete conversion of Ph Int1 was observed upon exposure to excess Me3SiN3 as monitored by 31 P NMR spectroscopy (Fig S18).…”

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High Spin Cobalt Complexes Supported by a Trigonal Tris(Phosphinimide) Ligand

Lee

Ciolkowski

Winslow

et al. 2021

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Terminal, π-basic moieties occupy a prominent position in the stabilization of unusual or reactive inorganic species. The electron-releasing, π-basic properties of phosphinimides (PN) have been employed to stabilize electrondeficient early transition metals and lanthanides. In principle, a ligand field comprised of terminal PN groups should enable access to high-valent states of late first row transition metals. Herein, we report a new class of multidentate phosphinimide ligands to logically explore this hypothesis. Access to such ligands is made possible by a new procedure for the electrophilic amination of rigid, sterically-encumbering, multidentate phosphines. Such frameworks facilitate terminal PN coordination to Cobalt as demonstrated by the synthesis of a trinuclear Co II 3 complex and a homoleptic, three-coordinate Co III complex. Interestingly, the Co III complex exhibits an exceedingly rare S = 2 ground state. Combined XRD, magnetic susceptibility, and DFT studies highlight that terminally-bound PNs engage in strong dπ-pπ interactions that present a weak ligand field appropriate to stabilize high-spin states of late transition metals.the filtrate under reduced pressure. The 1 H NMR (Figure S23) matches an authentic sample of 2 (11.0 mg, 28 %). ASSOCIATED CONTENTSupporting Information. Experimental procedures and characterization. This material is available free of charge via the Internet at http://pubs.acs.org.

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Molybdenum Alkylidyne Complexes with Tripodal Silanolate Ligands: The Next Generation of Alkyne Metathesis Catalysts

Cited by 21 publications

References 71 publications

Productive Alkyne Metathesis with “Canopy Catalysts” Mandates Pseudorotation

Productive Alkyne Metathesis with “Canopy Catalysts” Mandates Pseudorotation

Triple Resonance Experiments for the Rapid Detection of ¹⁰³Rh NMR Shifts: A Combined Experimental and Theoretical Study into Dirhodium and Bismuth–Rhodium Paddlewheel Complexes

High Spin Cobalt Complexes Supported by a Trigonal Tris(Phosphinimide) Ligand

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Molybdenum Alkylidyne Complexes with Tripodal Silanolate Ligands: The Next Generation of Alkyne Metathesis Catalysts

Cited by 21 publications

References 71 publications

Productive Alkyne Metathesis with “Canopy Catalysts” Mandates Pseudorotation

Productive Alkyne Metathesis with “Canopy Catalysts” Mandates Pseudorotation

Triple Resonance Experiments for the Rapid Detection of 103Rh NMR Shifts: A Combined Experimental and Theoretical Study into Dirhodium and Bismuth–Rhodium Paddlewheel Complexes

High Spin Cobalt Complexes Supported by a Trigonal Tris(Phosphinimide) Ligand

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Triple Resonance Experiments for the Rapid Detection of ¹⁰³Rh NMR Shifts: A Combined Experimental and Theoretical Study into Dirhodium and Bismuth–Rhodium Paddlewheel Complexes