Reactions and Photochemistry of Transition Metals with Methanol, Water, Hydrogen, and Carbon Monoxide via FTIR Matrix Isolation Spectroscopy

• Format: Others
• Language: English
• Published: 2008
• Subjects: Transition metal compounds; Matrix isolation spectroscopy
• Online Access: http://hdl.handle.net/1911/20479

The reactions and photochemistry of atomic and diatomic transition metals with methanol, water, hydrogen, and carbon monoxide in noble gas matrices at cryogenic temperatures have been studied with the use of Fourier Transform infrared inert matrix spectroscopy. Atoms and dimers of iron and cobalt reacted with methanol to form the adducts, M(CH30H) and M2(CH30H), respectively. M(CH30H) underwent metal insertion into the 0-H bond of methanol to yield methoxymetal hydride, CH3OMH, with irradiation of the matrix in the violet (400 nm < λ < 500 nm) region. Ultraviolet (280 nm < λ < 360 nm) photolysis of the matrix rearranged CH30MH to yield the methylmetal hydroxide species, CH3MOH. CH30MH dissociated into carbon monoxide and hydrogen after prolonged irradiation in the ultraviolet region. Surprisingly, nickel atoms reacted spontaneously to insert into the 0-H bonds of methanol and water to form CH30NiH and HONiH, respectively. Violet photolysis caused CH30NiH to rearrange to form methylnickel hydroxide, CH3NiOH. This is effectively a two step process of the C-0 activation of methanol by a nickel atom. In addition to rearrangement, CH30NiH dissociates into carbon monoxide and hydrogen with violet photolysis. Nickel dimers also reacted spontaneously with water to form both an adduct and insertion products. Atomic nickel spontaneously inserts into the H-H bond of molecular hydrogen to yield a bent nickel dihydride, NiH2, in krypton and xenon matrices. Nickel dimers and trimers insert into the H-H bond of hydrogen to form Nix(H)2. In addition to the insertion products, nickel atoms, dimers, and trimers form adducts molecularly with hydrogen to yield complexes of the form Nix(H2)y, where x or y = 1-3. Reactions of iron with carbon monoxide in an argon matrix yielded the iron-carbonyl complexes, Fex(CO)y, where x = 1-3 and y = 1-2.