Molybdenum-Boron Bonds in the Crystal – Structural Characterization of K[(η5-C5H5)Mo(CO)3] and[(η5-C5H5) (OC)3Mo-{B(NMe2)-B(NMe2)Br}]

Braunschweig, Holger; Radacki, Krzysztof; Kraft, Katharina; Stellwag, Sascha

doi:10.1515/znb-2010-0903

Cited by 4 publications

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“…The structure of crown-free K + [CpCr(CO) 2 (IMe)] − · 3 / 4 THF shows that the anion-based ligands (largely the carbonyls) alone almost succeed in filling the coordination spheres of the potassium cationsjust one in twenty K···O interactions is due to a THF ligand, and two-thirds of the THF molecules present are lattice solvents that do not interact with potassium at all. In fact, there are crystal structures of K + salts of related M(0) anions (for example, K + [CpFe(CO) 2 ] − and K + [CpMo(CO) 3 ] − ) that are entirely free of additional Lewis bases. On average, the K···O (CO) interactions are stronger in the crown-free ( d (K···O (CO) ) av = 2.77 Å) than in the crown-containing ( d (K···O (CO) ) av = 2.94 Å) material.…”

Section: Discussionmentioning

confidence: 99%

Structural and Spectroscopic Characterization of 17- and 18-Electron Piano-Stool Complexes of Chromium. Thermochemical Analyses of Weak Cr–H Bonds

et al. 2013

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The 17-electron radical CpCr(CO)(2)(IMe)(•) (IMe = 1,3-dimethylimidazol-2-ylidene) was synthesized by the reaction of IMe with [CpCr(CO)(3)](2), and characterized by single crystal X-ray diffraction and by electron paramagnetic resonance (EPR), IR, and variable temperature (1)H NMR spectroscopy. The metal-centered radical is monomeric under all conditions and exhibits Curie paramagnetic behavior in solution. An electrochemically reversible reduction to 18-electron CpCr(CO)(2)(IMe)(-) takes place at E(1/2) = -1.89(1) V vs Cp(2)Fe(+•/0) in MeCN, and was accomplished chemically with KC(8) in tetrahydrofuran (THF). The salts K(+)(18-crown-6)[CpCr(CO)(2)(IMe)](-)·½THF and K(+)[CpCr(CO)(2)(IMe)](-)·(3)/(4)THF were crystallographically characterized. Monomeric ion pairs are found in the former, whereas the latter has a polymeric structure because of a network of K···O((CO)) interactions. Protonation of K(+)(18-crown-6)[CpCr(CO)(2)(IMe)](-)·½THF gives the hydride CpCr(CO)(2)(IMe)H, which could not be isolated, but was characterized in solution; a pK(a) of 27.2(4) was determined in MeCN. A thermochemical analysis provides the Cr-H bond dissociation free energy (BDFE) for CpCr(CO)(2)(IMe)H in MeCN solution as 47.3(6) kcal mol(-1). This value is exceptionally low for a transition metal hydride, and implies that the reaction 2 [Cr-H] → 2 [Cr(•)] + H(2) is exergonic (ΔG = -9.0(8) kcal mol(-1)). This analysis explains the experimental observation that generated solutions of the hydride produce CpCr(CO)(2)(IMe)(•) (typically on the time scale of days). By contrast, CpCr(CO)(2)(PCy(3))H has a higher Cr-H BDFE (52.9(4) kcal mol(-1)), is more stable with respect to H(2) loss, and is isolable.

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Section: Discussionmentioning

confidence: 99%

Structural and Spectroscopic Characterization of 17- and 18-Electron Piano-Stool Complexes of Chromium. Thermochemical Analyses of Weak Cr–H Bonds

et al. 2013

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Release of Isonitrile‐ and NHC‐Stabilized Borylenes from Group VI Terminal Borylene Complexes

Nutz

Borthakur

Pranckevicius

et al. 2018

Chemistry A European J

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A family of doubly isonitrile-stabilized terphenyl borylenes could be obtained by addition of three equivalents of isonitrile to the corresponding Cr and W terminal terphenyl-borylene complexes. The mechanism of isonitrile- and carbon-monoxide-induced borylene liberation was investigated computationally and found to be significantly exergonic in both cases. Furthermore, addition of a small N-heterocyclic carbene (NHC) to a terminal Cr borylene complex results in release of an NHC-stabilized borylene carbonyl species, whereas the analogous reaction with bulkier phosphines results in metal-centered substitution.

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Salts of Anionic Metal Carbonyl Clusters with Cryptand[2.2.2](Na⁺), DB‐18‐crown‐6(Na⁺), and Paramagnetic Cp*₂Cr⁺ Cations Obtained by Reduction

Konarev

Kuźmin

Galkin

et al. 2019

Zeitschrift anorg allge chemie

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Reduction of neutral metal clusters (Co4(CO)12, Ru3(CO)12, Fe3(CO)12, Ir4(CO)12, Rh6(CO)16, {CpMo(CO)3}2, {Mn(CO)5}2) by decamethylchromocene (Cp*2Cr) or sodium fluorenone ketyl in the presence of cryptand[2.2.2] and DB‐18‐crown‐6 was studied. Nine new salts with paramagnetic Cp*2Cr+, cryptand[2.2.2](Na+), and DB‐18‐crown‐6(Na+) cations and [Co6(CO)15]2– (1, 2), [Ru6(CO)18]2– (3–4) dianions, [Rh11(CO)23]3– (6) trianions, and new [Ir8(CO)18]2– (5) dianions were obtained and structurally characterized. The increase of nuclearity of clusters under reduction was shown. Fe3(CO)12 preserves the Fe3 core under reduction forming the [Fe3(CO)11]2– dianions in 7. The [CpMo(CO)3]2 and [Mn(CO)5]2 dimers dissociate under reduction forming mononuclear [CpMo(CO)3]– (8) and [Mn(CO)5]– (9) anions. In all anions the increase of negative charge on metal atoms shifts the bands attributed to carbonyl C–O stretching vibrations to smaller wavenumbers in agreement with the elongation of the C–O bonds in 1–9. In contrast, the M–C(CO) bonds are noticeably shortened at the reduction. Magnetic susceptibility of the salts with Cp*2Cr+ is defined by high spin Cp*2Cr+ (S = 3/2) species, whereas all obtained anionic metal clusters and mononuclear anions are diamagnetic. Rather weak magnetic coupling between S = 3/2 spins is observed with Weiss temperature from –1 to –11 K. That is explained by rather long distances between Cp*2Cr+ and the absence of effective π–π interaction between them except compound 7 showing the largest Weiss temperature of –11 K. The {DB‐18‐crown‐6(Na+)}2[Co6(CO)15]2– units in 2 are organized in infinite 1D chains through the coordination of carbonyl groups of the Co6 clusters to the Na+ ions and π–π stacking between benzo groups of the DB‐18‐crown‐6(Na+) cations.

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Molybdenum-Boron Bonds in the Crystal – Structural Characterization of K[(η⁵-C₅H₅)Mo(CO)₃] and[(η⁵-C₅H₅) (OC)₃Mo-{B(NMe₂)-B(NMe₂)Br}]

Abstract: Structural characterization of the solvent-free ionic complex K[(η 5 -C 5 H 5 )Mo(CO) 3 ] and the molybdenum boryl complex [(η 5 -C 5 H 5 )(OC) 3 Mo-{B(NMe 2 )-B(NMe 2 )Br}] is reported.

Cited by 4 publications

References 12 publications

Structural and Spectroscopic Characterization of 17- and 18-Electron Piano-Stool Complexes of Chromium. Thermochemical Analyses of Weak Cr–H Bonds

Structural and Spectroscopic Characterization of 17- and 18-Electron Piano-Stool Complexes of Chromium. Thermochemical Analyses of Weak Cr–H Bonds

Release of Isonitrile‐ and NHC‐Stabilized Borylenes from Group VI Terminal Borylene Complexes

Salts of Anionic Metal Carbonyl Clusters with Cryptand[2.2.2](Na⁺), DB‐18‐crown‐6(Na⁺), and Paramagnetic Cp*₂Cr⁺ Cations Obtained by Reduction

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Molybdenum-Boron Bonds in the Crystal – Structural Characterization of K[(η5-C5H5)Mo(CO)3] and[(η5-C5H5) (OC)3Mo-{B(NMe2)-B(NMe2)Br}]

Abstract: Structural characterization of the solvent-free ionic complex K[(η 5 -C 5 H 5 )Mo(CO) 3 ] and the molybdenum boryl complex [(η 5 -C 5 H 5 )(OC) 3 Mo-{B(NMe 2 )-B(NMe 2 )Br}] is reported.

Cited by 4 publications

References 12 publications

Structural and Spectroscopic Characterization of 17- and 18-Electron Piano-Stool Complexes of Chromium. Thermochemical Analyses of Weak Cr–H Bonds

Structural and Spectroscopic Characterization of 17- and 18-Electron Piano-Stool Complexes of Chromium. Thermochemical Analyses of Weak Cr–H Bonds

Release of Isonitrile‐ and NHC‐Stabilized Borylenes from Group VI Terminal Borylene Complexes

Salts of Anionic Metal Carbonyl Clusters with Cryptand[2.2.2](Na+), DB‐18‐crown‐6(Na+), and Paramagnetic Cp*2Cr+ Cations Obtained by Reduction

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Molybdenum-Boron Bonds in the Crystal – Structural Characterization of K[(η⁵-C₅H₅)Mo(CO)₃] and[(η⁵-C₅H₅) (OC)₃Mo-{B(NMe₂)-B(NMe₂)Br}]

Salts of Anionic Metal Carbonyl Clusters with Cryptand[2.2.2](Na⁺), DB‐18‐crown‐6(Na⁺), and Paramagnetic Cp*₂Cr⁺ Cations Obtained by Reduction