Completing the triad: synthesis and full characterization of homoleptic and heteroleptic carbonyl and nitrosyl complexes of the group VI metals

Bohnenberger, Jan; Schmitt, Manuel; Feuerstein, Wolfram; Krummenacher, Ivo; Butschke, Burkhard; Czajka, Jakub; Malinowski, P.; Breher, Frank; Krossing, Ingo

doi:10.1039/c9sc06445a

Cited by 31 publications

(41 citation statements)

References 51 publications

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“…The oxidation step for the chromium complex 1 is reversible, whereas that for the molybdenum complex 2 is irreversible. As reported previously, 45,46 we attribute this behavior to a more facile labilization of the M−CO bond upon oxidation for the molybdenum complex compared to the chromium complex. Notably, with the ligand L1, the oxidation step in complex 1 is reversible at ambient temperatures at normal scan rates (100 mV/s).…”

Section: ■ Results and Discussionsupporting

confidence: 82%

Chromium(0) and Molydenum(0) Complexes with a Pyridyl-Mesoionic Carbene Ligand: Structural, (Spectro)electrochemical, Photochemical, and Theoretical Investigations

et al. 2020

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This work reports on the synthesis and in-depth electrochemical and photochemical characterization of two chromium(0) and molydenum(0) metal complexes with bidentate pyridyl-mesoionic carbene (MIC) ligands of the 1,2,3-triazol-5ylidene type and carbonyl coligands. Metal complexes with MIC ligands have turned out to have very promising electrocatalytic and photochemical properties, but examples of MIC-containing complexes with early-transition-metal centers remain extremely rare. The electrochemistry of these new MIC complexes was studied by cyclic voltammetry and especially spectroelectrochemistry in the IR region consistent with a mainly metal-centered oxidation, which is fully reversible in the case of the chromium(0) complex. At the same time, the two reduction steps are predominantly ligandcentered according to the observed near-IR absorbance, with the first reduction step being reversible for both systems. The results of the electron paramagnetic resonance studies on the oxidized and reduced species confirm the IR spectroelectrochemistry experiments. The photochemical reactivity of the complexes with a series of organic ligands was investigated by time-resolved (stepscan) Fourier transform infrared (FTIR) spectroscopy. Interestingly, the photoreactions in pyridine and acetonitrile are fully reversible with a slow dark reverse reaction back to the educt species over minutes and even hours, depending on the metal center and reagent. This reversible behavior is in contrast to the expected loss of one or several CO ligands known from related homoleptic as well as heteroleptic M(CO) 4 L 2 α-diimine transition-metal complexes.

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Section: ■ Results and Discussionsupporting

confidence: 82%

Chromium(0) and Molydenum(0) Complexes with a Pyridyl-Mesoionic Carbene Ligand: Structural, (Spectro)electrochemical, Photochemical, and Theoretical Investigations

et al. 2020

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“…This explained why this species was never observed before: only the change to the even less coordinating solvents TFB (=1,2,3,4‐F 4 C 6 H 2 ) and C 6 F 6 —as also used for the very sensitive [W(CO) 6 ] + system [11, 17] —made this discovery possible. This points out that the W(CO) 6 ligand is weakly bound.…”

Section: Resultsmentioning

confidence: 87%

“…During our continuous efforts to prepare novel transition metal carbonyl [10, 11] and nitrosyl [12, 13] cations as salts of the very good weakly coordinating anions [14] (WCAs) [Al(OR F ) 4 ] −[15] and [F‐{Al(OR F ) 3 } 2 ] − (R F =C(CF 3 ) 3 ), [16] we conducted experiments towards the synthesis of the homoleptic group 6 carbonyl radical cations [Mo(CO) 6 ] + and [W(CO) 6 ] + [17] . An unsuccessful oxidation attempt of W(CO) 6 led to light‐yellow crystals of [Ag{W(CO) 6 } 2 ] + [F‐{Al(OR F ) 3 } 2 ] − .…”

Section: Resultsmentioning

confidence: 99%

“…The colorless crystals turned dark overnight and the IR spectrum recorded the subsequent day showed, amongst other bands, CO stretching vibrations similar to those of [Mo(CO) 6 ] + . This implies that [Mo(CO) 6 ] + can in principle be synthesized from Ag + in C 6 F 6 or TFB without the need [17] of I 2 as the co‐oxidant. All attempts to prepare a salt with the lighter chromium carbonyl [Ag{Cr(CO) 6 } 2 ] + were futile in our hands.…”

Section: Resultsmentioning

confidence: 99%

“…, [16] we conducted experiments towards the synthesis of the homoleptic group 6c arbonyl radical cations [Mo(CO) 6 ] + and [W(CO) 6 ] + . [17] An unsuccessfuloxidation attempto fW (CO) 6 led to light-yellow crystals of [Ag{W(CO…”

Section: Synthesis and Characterization Of [Ag{m(co) 6 } 2 ][F-{al(ormentioning

confidence: 99%

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Group 6 Hexacarbonyls as Ligands for the Silver Cation: Syntheses, Characterization, and Analysis of the Bonding Compared with the Isoelectronic Group 5 Hexacarbonylates

Bohnenberger

Kratzert

Gorantla

et al. 2020

Chemistry A European J

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The syntheses of the two novel complexes [Ag{Mo/W(CO)6}2]+[F‐{Al(ORF)3}2]− (RF=C(CF3)3) are reported along with their structural and spectroscopic characterization. The X‐ray structure shows that three carbonyl ligands from each M(CO)6 fragment bend towards the silver atom within binding Ag−C distance range. DFT calculations of the free cations [Ag{M(CO)6}2]+ (M=Cr, Mo, W) in the electronic singlet state give equilibrium structures with C2 symmetry with two bridging carbonyl groups from each hexacarbonyl ligand. Similar structures with C2 symmetry (M=Nb) and D2 symmetry (M=V, Ta) are calculated for the isoelectronic group 5 anions [Ag{M(CO)6}2]− (M=V, Nb, Ta). The electronic structure of the cations is analyzed with the QTAIM and EDA‐NOCV methods, which provide detailed information about the nature of the chemical bonds between Ag+ and the {M(CO)6}2q (q = −2, M = V, Nb, Ta; q = 0, M = Cr, Mo, W) ligands.

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Chasing the Mond Cation: Synthesis and Characterization of the Homoleptic Nickel Tetracarbonyl Cation and its Tricarbonyl‐Nitrosyl Analogue

et al. 2021

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130 years after Mond discovered the first homoleptic carbonyl complex Ni(CO)4, we report on a [Ni(CO)4].+ salt as the first synthesis of any homoleptic nickel carbonyl cation in the condensed phase. It was prepared by oxidation of nickel metal with the synergistic oxidant Ag[F{Al(ORF)3}2]/0.5 I2 (RF=C(CF3)3) in CO atmosphere. This D2d‐symmetric metalloradical represents the last missing entry among the structurally characterized homoleptic carbonyl cations of Groups 6 to 11. Additionally, the nickel tricarbonyl‐nitrosyl cation [Ni(CO)3(NO)]+ was obtained by usage of NO[F{Al(ORF)3}2] and all products were fully characterized by means of IR, Raman, NMR/EPR, single crystal and powder XRD.

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Completing the triad: synthesis and full characterization of homoleptic and heteroleptic carbonyl and nitrosyl complexes of the group VI metals

Abstract: The triad of group VI metalloradicals is now finally accessible via the oxidation of Cr/Mo/W(CO)6 with the synergistic oxidative system Ag[F-{Al(ORF)3}2]/0.5 I2.

Cited by 31 publications

References 51 publications

Chromium(0) and Molydenum(0) Complexes with a Pyridyl-Mesoionic Carbene Ligand: Structural, (Spectro)electrochemical, Photochemical, and Theoretical Investigations

Chromium(0) and Molydenum(0) Complexes with a Pyridyl-Mesoionic Carbene Ligand: Structural, (Spectro)electrochemical, Photochemical, and Theoretical Investigations

Group 6 Hexacarbonyls as Ligands for the Silver Cation: Syntheses, Characterization, and Analysis of the Bonding Compared with the Isoelectronic Group 5 Hexacarbonylates

Chasing the Mond Cation: Synthesis and Characterization of the Homoleptic Nickel Tetracarbonyl Cation and its Tricarbonyl‐Nitrosyl Analogue

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