Matrix Isolation Infrared Spectroscopic and Theoretical Studies on the Reactions of Niobium and Tantalum Mono- and Dioxides with Methane

Abstract

The reactions of niobium and tantalum monoxides and dioxides with methane have been investigated using matrix isolation infrared spectroscopic and theoretical calculations. The niobium and tantalum oxide molecules were prepared by laser evaporation of Nb(2)O(5) and Ta(2)O(5) bulk targets. The niobium monoxide molecule interacted with methane to form the ONb(CH(4)) complex, which was predicted to have C(3)(v)() symmetry with the metal atom coordinated to three hydrogen atoms of the methane molecule. The ONb(CH(4)) complex rearranged to the CH(3)Nb(O)H isomer upon 300 nm < lambda < 580 nm irradiation. The analogous OTa(CH(4)) complex was not observed, but the CH(3)Ta(O)H molecule was produced upon UV irradiation. The niobium and tantalum dioxide molecules reacted with methane to form the O(2)Nb(CH(4)) and O(2)Ta(CH(4)) complexes with C(s)() symmetry, which underwent photochemical rearrangement to the CH(3)Nb(O)OH and CH(3)Ta(O)OH isomers upon ultraviolet irradiation.

Formation and reactivity of organometallic alkane complexes

“…This shift in the UV/visible band of Cr(CO) 5 could not be accounted for by matrix environment effects and was interpreted to indicate a significant interaction between the matrix material and the Cr(CO) 5 fragment. Matrix isolation studies have continued to be useful in characterising very unstable reactive fragments in recent years [16], with the interaction of CH 4 with both organometallic complex fragments [17][18][19] and with isolated metal atoms being examined [20].…”

Theoretical study on the gas‐phase reaction mechanism between palladium monoxide and methane

“…[26,29,92] As discussed earlier, PdO has a triplet ground state ( 3 R) with [36] Ta, [36] Ni, [42] and Rh [41] ). Next, from CH 3 Pd(O)H, the hydride ligand on palladium transfers to the oxygen via 1-TS2cb, leading to a hydroxyl ligand in the CH 3 PdOH complex.…”

Theoretical study on the gas-phase reaction mechanism between rhodium monoxide cation and methane

“…CH 4 (M = Fe, Mn, Nb, and Ta) and M ? CH 3 OH (M = Sc, Ti, Mn, and Fe) reaction mechanisms by quantum chemical calculations coupled with matrix isolation spectroscopy [16][17][18][19][20]. They suggested that for the late transition metals, Mn and Fe, the inserted CH 3 MOH molecule is a critical intermediate in both MO ?…”

“…CH 3 OH reactions [16][17][18][19][20]. For the group IV and V transition metals, the inserted CH 3 OMH and CH 3 M(O)H molecules are the crucial intermediates [16][17][18][19][20]. For Sc, the CH 3 ScOH molecule is an important intermediate in the ScO ?…”