Structure of hexakis(2,6-diisopropylphenyl isocyanide)chromium(0)

Anderson, Kim A.; Scott, Brian L.; Wherland, Scot; Willett, Roger D.

doi:10.1107/s0108270191000100

Cited by 8 publications

(9 citation statements)

References 5 publications

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“…The metric parameters of its nearly perfectly octahedral Cr(CN) 6 core are in accord with those observed for other binary isocyanides of chromium(0). , The average C−N−C(Fc) angle in 5 is 162°. Such a degree of bending at the nitrogen atom is also typical for zerovalent, octahedral complexes of bulky aryl isocyanides (aryl = 2,6-Me 2 C 6 H 4 , 2,6- i Pr 2 C 6 H 4 ). 40a, Notably, the average C−N−C( t Bu) angle in Cr(CN t Bu) 6 is 153° . The less pronounced bending of aryl-substituted isocyanide ligands in their low-valent complexes has been attributed to partial delocalization of the back-donated electron density into the aromatic rings that can be described by the linear resonance structures MCN + Aryl - . 2a,b The shortest Fe···Fe distance within 2 is 6.29 Å, which is only 0.93 Å greater than that in zwitterionic Fc 4 B …”

Section: Resultssupporting

confidence: 81%

“…Thus, the first two oxidations of 5 are chromium-centered. The trends in the bond distances and angles presented in Table nicely parallel those documented for [Cr(CNPh) 6 ] z ( z = 0, 1+, 2+) 40b, and the isoelectronic series [V(CN-2,6-Me 2 C 6 H 3 ) 6 ] z ( z = 1−, 0, 1+) 4 ORTEP (50%) diagram of 5 2+ [BF 4 ] 2 ·CH 2 Cl 2 .…”

Section: Resultssupporting

confidence: 73%

“…The X-ray structure of 5 ·CH 2 Cl 2 is shown in Figure , The average C−N−C(Fc) angle in 5 is 162°. Such a degree of bending at the nitrogen atom is also typical for zerovalent, octahedral complexes of bulky aryl isocyanides (aryl = 2,6-Me 2 C 6 H 4 , 2,6- i Pr 2 C 6 H 4 ). 40a, Notably, the average C−N−C( t Bu) angle in Cr(CN t Bu) 6 is 153° .…”

Section: Resultsmentioning

confidence: 99%

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Organometallic Isocyanocyclopentadienides: A Combined Synthetic, Spectroscopic, Structural, Electrochemical, and Theoretical Investigation

et al. 2004

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This article reports on the chemistry of two organometallic isocyanocyclopentadienides, which represent an emerging new class of aromatic isocyanides incorporating nonbenzenoid π-systems. Interaction of aminoferrocene with a mixture of phenyl formate/phenol followed by subsequent dehydration of the resulting ferrocenylformamide with POCl 3 produced air and thermally stable isocyanoferrocene (CNFc, Fc ) ferrocenyl) in a high yield. Treating lithiocymantrene, LiCm (Cm ) (η 5 -C 5 H 4 )Mn(CO) 3 ), with tosyl azide afforded thermally sensitive cymantrenyl azide. Without isolation, CmN 3 was reduced by NaBH 4 to form aminocymantrene, which was converted into air stable but thermally and light sensitive isocyanocymantrene, CNCm. Combining 6 equiv of CNR (R ) Fc, Cm) with bis(naphthalene)chromium(0) afforded Cr(CNR) 6 . Successive one-electron oxidations of Cr(CNR) 6 with Ag + produced the corresponding paramagnetic [Cr(CNR) 6 ] + and [Cr(CNR) 6 ] 2+ . The compounds [Cr(CNR) 6 ] 0,1+,2+ (R ) Fc, Cm) are remarkable due to the incorporation of seven transition metal atoms within relatively compact ML 6 motifs. The physical, chemical, electrochemical, and spectroscopic properties of the structurally characterized series [Cr(CNFc) 6 ] 0,1+,2+ indicate that the electronic influence of the ferrocenyl moiety, often compared to an alkyl group, is in fact more similar to that of aryl substituents. Electrochemical properties of [Cr(CNR) 6 ] 0,1+,2+ (R ) Fc, Cm) are consistent with isocyanocymantrene being a substantially stronger π-acid than isocyanoferrocene. This conclusion was unambiguously corroborated by a DFT analysis of the Frontier molecular orbitals of CNFc and CNCm. Unpaired spin delocalization within odd-atom, nonbenzenoid aromatic π-systems of [Cr(CNR) 6 ] 1+,2+ (R ) Fc, Cm) was studied by multinuclear paramagnetic NMR and contrasted with patterns observed for similar complexes incorporating benzenoid and even-atom, nonbenzenoid aromatic moieties.

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Section: Resultssupporting

confidence: 81%

Section: Resultssupporting

confidence: 73%

Section: Resultsmentioning

confidence: 99%

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Organometallic Isocyanocyclopentadienides: A Combined Synthetic, Spectroscopic, Structural, Electrochemical, and Theoretical Investigation

et al. 2004

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“…The X-ray structure of 2 ·CH 2 Cl 2 is shown in Figure . The metric parameters of the nearly perfectly octahedral Cr(CN) 6 core are in accord with those observed for other binary isocyanides of chromium(0) . The average C−N−C(Fc) angle in 2 is 162°.…”

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confidence: 83%

First Homoleptic Complexes of Isocyanoferrocene

et al. 2002

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Interaction of aminoferrocene with a 65/35 mol % mixture of phenyl formate/phenol followed by subsequent dehydration of the resulting ferrocenylformamide with POCl3 produced a high yield of air- and thermally stable, peach-colored isocyanoferrocene (CNFc). Combining 6 equiv of CNFc with bis(naphthalene)chromium(0) afforded orange-red Cr(CNFc)6, the first homoleptic complex of CNFc. Successive one-electron oxidations of the latter with Ag+ quantitatively produced saddle-brown [Cr(CNFc)6]+ and forest-green [Cr(CNFc)6]2+. The compounds [Cr(CNFc)6]0,1+,2+ are air-, light-, and thermally robust and are remarkable due to the incorporation of seven potentially electroactive transition metal ions within a relatively compact ML6 motif. Their properties demonstrate that the pi-accepting potential of the ferrocenyl substituent, customarily compared to an alkyl group, may have been underestimated. Indeed, the donor/acceptor ratio of the CNFc ligand appears to be similar to those of aryl isocyanides but quite different from those of alkyl isocyanides. Spectroscopic (including multinuclear paramagnetic NMR), magnetic, structural, and electrochemical characteristics of the above substances are discussed. In addition, a DFT analysis of the Frontier molecular orbitals of CNFc is presented.

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“…Consequently, the frozen solution EPR spectra will not be discussed further. Additionally, although the diamagnetic congeners M′(CNDipp) 6 (M′ = Cr, W) of complexes 1 and 3 are known, they crystallize in different space groups and with packing schemes. Thus, dilution via cocrystallization in a diamagnetic matrix would involve a structural change non-native to the pristine solid samples, preventing further EPR experiments.…”

Section: Resultsmentioning

confidence: 99%

Effect of Spin–Orbit Coupling on Phonon-Mediated Magnetic Relaxation in a Series of Zero-Valent Vanadium, Niobium, and Tantalum Isocyanide Complexes

et al. 2021

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Spin-vibronic coupling leads to spin relaxation in paramagnetic molecules, and an understanding of factors that contribute to this phenomenon is essential for designing next-generation spintronics technology, including single-molecule magnets and spin-based qubits, wherein long-lifetime magnetic ground states are desired. We report spectroscopic and magnetic characterization of the isoelectronic and isostructural series of homoleptic zerovalent transition metal triad M(CNDipp)6 (M = V, Nb, Ta; CNDipp = 2,6-diisopropylphenyl isocyanide) and show experimentally the significant increase in spin relaxation rate upon going from V to Nb to Ta. Correlated electronic calculations and first principle spin–phonon computations support the role of spin–orbit coupling in modulating spin–phonon relaxation. Our results provide experimental evidence that increasing magnetic anisotropy through spin–orbit coupling interactions leads to increased spin–vibronic relaxation, which is detrimental to long spin lifetime in paramagnetic molecules.

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Structure of hexakis(2,6-diisopropylphenyl isocyanide)chromium(0)

Abstract: Abstract. [Cr(CI3HI7N)

Cited by 8 publications

References 5 publications

Organometallic Isocyanocyclopentadienides: A Combined Synthetic, Spectroscopic, Structural, Electrochemical, and Theoretical Investigation

Organometallic Isocyanocyclopentadienides: A Combined Synthetic, Spectroscopic, Structural, Electrochemical, and Theoretical Investigation

First Homoleptic Complexes of Isocyanoferrocene

Effect of Spin–Orbit Coupling on Phonon-Mediated Magnetic Relaxation in a Series of Zero-Valent Vanadium, Niobium, and Tantalum Isocyanide Complexes

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