Structures and Infrared Spectra of [M(CO₂)₇]⁺ (M = V, Cr, and Mn) Complexes

Abstract

Gas-phase infrared photodissociation spectra of [V­(CO2) n ]+ complexes revealed three new vibrational bands at 1140, 1800, and 3008 cm–1 at n = 7, the features of which are retained in the larger clusters (Ricks, A. M.; Brathwaite, A. D.; Duncan, M. A. J. Phys. Chem. A 2013, 117, 11490–11498). However, structural assignment of this intriguing feature remains open. Herein, quantum chemical calculations on [V­(CO2)7]+ were carried out to identify the structure of the low-lying isomers and to assign the observed spectral features. The comparison of calculated infrared spectra of [V­(CO2)7]+ with experimental infrared spectra identified the formation of a bent CO2 – species, suggesting the ligand-induced activation of CO2 by the vanadium cation. The structures and infrared spectra of [Cr­(CO2)7]+ and [Mn­(CO2)7]+ were also predicted and discussed.

Covalent Bonding Between Be+and CO2in BeOCO+with a Surprisingly High Antisymmetric OCO Stretching Vibration

“…In contrast, the CO 2 molecule was only weakly bound to the metal cations, exclusively in an end-on configuration via electrostatic charge-quadrupole interaction, resulting in a linear M + OCO structure. − The antisymmetric CO 2 stretching vibrations in these cationic complexes are generally blue-shifted with respect to the free CO 2 molecule. − It was found that these blue-shifted vibrations vary only slightly from one system to another due to electrostatic interaction. − Here we report the generation of the cationic metal complex BeOCO + , which exhibits an antisymmetric CO 2 stretching mode at 2418.9 cm –1 in solid neon, blue-shifted by 71 cm –1 with respect to free CO 2 . The observed value is the highest antisymmetric CO 2 stretching frequency ever reported for a carbon dioxide complex. − …”

An infrared study of CO2 activation by holmium ions, Ho+ and HoO+

“…Only larger Co n À (n 4 8) clusters bind CO 2 at all 5 whilst CO 2 binds molecularly to small Pt n À clusters (n o 5) but dissociatively on larger ones. 6 Metal cations necessarily donate electron density less effectively than anions and M + (CO 2 ) binding is usually M(Z 1 -OCO), 4,[23][24][25][26][27][28] dictated by the dominant charge-quadrupole interactions and s-donation. The typical spectroscopic signature of such binding is a weak blue shift in the CO 2 asymmetric stretch around 2349 cm À1 .…”

Infrared spectroscopy of Be(CO2)4+in the gas phase: electron transfer and C–C coupling of CO2

“…27 Metal cationligand electron transfer reaction in forming an oxalate-type C 2 O 4 anion species was proposed in the V(CO 2 ) n + n Z 7 clusters, 28 which was later reassigned to a charge transfer complex involving a bidentate Z 2 -C, O coordinated CO 2 À ligand. 33 Solvation-induced intracluster insertion reaction producing the oxocarbonyl species has also been reported in the larger [M(CO 2 ) n ] + complexes with M = Ti, Ni, Si and n Z5. [24][25][26] Recent investigation on the end-on Z 1 -O coordinated [BeOCO] + complex in solid neon matrix indicates that the bonding between the metal cation and CO 2 exhibits significant covalent character due to the interference of the wave function.…”

“…15,20 The CO 2 ligand is bound to the metal center exclusively in an end-on Z 1 -O fashion in the cationic complexes. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] The binding between the metal cation and carbon dioxide is largely an electrostatic interaction, resulting in a blue-shifted antisymmetric CO 2 stretching vibration with respect to the free CO 2 molecule. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] Solvation-induced metal cationcarbon dioxide electron transfer with the formation of a bent CO 2 À moiety was reported on the Mg(H 2 O) n (CO 2 ) + complexes with n Z 3.…”

“…[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] The binding between the metal cation and carbon dioxide is largely an electrostatic interaction, resulting in a blue-shifted antisymmetric CO 2 stretching vibration with respect to the free CO 2 molecule. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] Solvation-induced metal cationcarbon dioxide electron transfer with the formation of a bent CO 2 À moiety was reported on the Mg(H 2 O) n (CO 2 ) + complexes with n Z 3. 27 Metal cationligand electron transfer reaction in forming an oxalate-type C 2 O 4 anion species was proposed in the V(CO 2 ) n + n Z 7 clusters, 28 which was later reassigned to a charge transfer complex involving a bidentate Z 2 -C, O coordinated CO 2 À ligand.…”