Oxidation reactions of Dicarbonylbis[ethane-1,2-diylbis(diphenylphosphine)]-molybdenum

Abstract

The complex Mo(CO),(dpe), [dpe is ethane-1,2-diylbis(diphenylphosphine)]* reacts with oxidants (MOPF6, NOCl, Br,, 12) to form the cations [M0(C0)~(dpe)~X(]X+ = F, C1, Br, I). The products have been characterized by conductance, i.r. and n.m.r. (31P, 19F) spectroscopy. Low-temperature 31P n.m.r. spectra show that [M0(C0),(dpe)~F]+ is rigid while [Mo(CO),(dpe),Br]+ and [Mo(CO),- (dpe)JIt are fluxional; a possible cause of this non-rigidity is discussed. [M0(C0)~(dpe)~X]+ (X = C1, Br) reacts with X- to form [M0(C0)~(dpe),X~w]h ich polymerizes to [ M O ( C O ) ~ ( ~ ~ ~ ) ~ . ~ X ~ with loss of dpe. [M0(CO)~(dpe)~1r]e+a cts with I2 to form [Mo(CO),(dpe)I,]. The product formed from NOPFs with dichloromethane as solvent, originally formulated as cis-[M0(C0)~(dpe)J PF6, is shown to be the fluoro complex, [M0(C0)~(dpe),F]P F6. A fluoro-bridged species is obtained in nitromethane, [{M0(C0)~(dpe)~)(~PFF],) ,, a compound originally formulated as cis-[Mo(CO),- ( d ~ e )(~P]F 6)2. The fluoro bridged compound is cleaved and substituted by reaction with halide ion to give [ M O ( C O ) ~ ( ~ ~ ~(X) ~= .C~1, XB~r) ]in~ w hich one diphosphine bridges the two metal atoms. Oxidation of Mo(CO),(dpe), by NOPFs in coordinating solvents (Y = MeCN, PhCN) gives [M0(C0)~(dpe)~Y]~T+he. se dications, which have been characterized by conductance, i.r. and 'H n.m.r. spectroscopy, are also formed by adding AgClO, to [M~(CO)~(dpe)~(xXl += Br, I) in the appropriate solvent.