INFRARED MATRIX ISOLATION STUDIES OF METAL ATOM REACTIONS WITH WATER AND OTHER LEWIS BASES

This work involves the infrared matrix isolation study of metal atom reactions with water molecules in an argon matrix at 15(DEGREES)K. The metals studied include Mg, Ca, Sr and Ba from Group IIa; the first row transition metals, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn; the Group IIIa metals, Al, Ga, In and Tl; and the Group IVa metals, Si, Ge, Sn and Pb. Iron metal atom reactions with the isoelectronic species, CH(,4), NH(,3), and HF are also included in this study. In most cases, a metal atom-water molecule adduct is formed on co-condensation. Adduct formation is detected in these experiments by a red shift in the (nu)(,2) water bending mode frequency at 1593 cm('-1), over a range of 5 - 35 cm('-1). Photolysis of the adduct with (lamda) (TURNEQ) 300 - 600 nm light results in an oxidative insertion of the metal atom into the O-H bond of water to produce the metal hydroxy hydride molecule, HMOH. The Zn, Tl and Pb adducts do not react under normal experimental conditions. Sc, Ti, V and Al metal atoms spontaneously insert into the water molecule to form the HMOH molecule on co-condensation. Preliminary studies on nickel indicate that the metal atom does not form an adduct with water and does not undergo an insertion reaction. The HMOH molecule in some cases undergoes photolytic cleavage of one or two hydrogen bonds to form the metal monohydroxide, MOH, or metal monoxide, MO. The metal dimer-water molecule adduct was also observed for Mg, Cr, Mn, Fe, Co, Cu, Zn, Ga, In, Ge, Sn, and Pb. Photolysis of this adduct resulted in an insertion of the metal dimer into water to give a HM(,2)OH molecule. A di-insertion reaction to form the HMOMH molecule was observed for Mg, Ca, Mn and Fe. This product is believed to form by a sequential insertion of a metal atom into an already formed HMOH molecule on photolysis. Reaction products resulting from the insertion of one metal atom into water molecules were observed for Ca, Sc, Ti, V, Cr, Fe, Al, Ga, In, Si and Ge, and the ultimate product depended on the valent state of the metals. The M(OH)(,2), HM(OH)(,2) and H(,2)M(OH)(,2) species were observed for divalent, trivalent, and tetravalent metal atoms, respectively. A water monohydrated HMOH species was observed for Al, Ga, In, Si and Ge. Iron metal atoms reacted with NH(,3) and HF to form an adduct on co-condensation. It is thought that the metal atom bonds through the nitrogen and fluorine atoms, respectively. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of school.) UM