J . A m . Chem. SOC.1984, 106, 2721-2722 and is consistent with the larger activation barriers that frequently impede association reactions between singlets and triplet^.^',^^ It with the odd is noteworthy in this regard that the reactions of 302 electron, radical anions Fe(C0)4-, Cr(CO),-, and Mo(CO),- are surprisingly slow (Table I), despite the favorable energetics and kinetic factors that might otherwise be expected for their direct reaction. The origin of this effect may lie in unfavorable spin localization requirements or inaccessible spin states of the product polyoxide ions and is presently under investigation. We are also currently examining the gas-phase reactions of the polyoxide ions with a series of neutral substrates and will report these results in a future publication.
2721
Table I. Initial Reaction Ratcs for I-Butene Isomerization, 1-Butene Hydrogenation, and 1.3-Butadiene Hydrogenation over Monometallic and Bimetallic SMAI) Catalysts initial rates, niolccule/(\l atom s ) atom catalystb
isom l-C4'
hydrog 1-C4'P
0.017 0.0096 0.00087 0.018 0.084 0.0 18
0.44p 0.0063 0.000 16 O.3Sg 0.45E 0.79g 0.53g 0.50g 0.016 0.0051 0.0028 0.0047 0.00022
(4C
39.4 70.5 74.9 Mn 2.5 Mn 19.3 Mn 37.6 Mn 45.8 %In 51.0 Mn 76.3 Cr 18.1
'
0.14 (0.41 ) h 0.029 ( 0 . 9 6 ? 0.0049 ( 0 . 9 6 ) h 0.18 ( 0 . 5 7 ) h
(41) Benson, S. W. 'Thermochemical Kinetics", 2nd ed.; Wiley: New York, 1976. (42) Ferguson, E. E. 'Interactions Between Ions and Molecules"; Ausloos, P., Ed.; Plenum Press: New York, 1975; p 318.
2.6% Co-l.5% 1.5% Co-3.4% 2.4'/; Co-6.87; 4.1>+,Co-0.1% 3.62 Co-o.8'h 2.0% C o - l . l % 3.3% Co-2.6% 3.4:4 Co-3.354 1.7% Co-5.1% 3.6% Co-O.7% 2.0% C0-2.2'% 0.6% Co-3.7% 4.7% I:e 2.3% Co 3.49 M n 3.8% Cr
Bimetallic Solvated Metal Atom Dispersed Catalysts New Materials with Low-Temperature Catalytic Properties
Based on 100% Co dispersion neglecting second metal contriAtom % of second metal, not bution. SiO, support, wt %. including support. d P,,,= 30 torr. without H,, 253 K . 'H,/HC=1.67,Pt,,=80 t o r r , 2 1 3 I(. f H , / H C = 2 , P t , t = 6 0 torr, 273 I
