Synthesis and characterization of CpMn(dfepe)(L) complexes (dfepe = (C 2F 5) 2PCH 2CH 2P(C 2F 5) 2; L = CO, H 2, N 2): an unusual example of a dihydride to dihydrogen photochemical conversion

• Published in: Polyhedron Vol. 23; no. 17; pp. 2873 - 2878
• Main Authors: Merwin, Richard K., Ontko, Allyn C., Houlis, James F., Roddick, Dean M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2004
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2004.06.017

CpMn(dfepe)(CO) ( 1) was prepared by treatment of CpMn(CO) 2(thf) with excess dfepe. Photolysis of 1 under a H 2 purge produced a 6:1 equilibrium isomeric mixture of the hydride complexes CpMn(dfepe)(H) 2 ( 2a) and CpMn(dfepe)(η 2-H 2) ( 2b). The synthesis and properties of perfluoroalkylphosphine manganese complexes CpMn(dfepe)(L) (dfepe = (C 2F 5) 2PCH 2CH 2P(C 2F 5) 2; L = CO, H 2, N 2) are reported. CpMn(dfepe)(CO) ( 1) was prepared by treatment of CpMn(CO) 2(thf) with excess dfepe. The observed ν(CO) (1934 cm −1) and E 1/2(ox) (+1.09 V) values confirm the very electron-deficient nature of the CpMn(dfepe) moiety. Photolysis of 1 under a H 2 purge produced a 6:1 equilibrium isomeric mixture of the hydride complexes CpMn(dfepe)(H) 2 ( 2a) and CpMn(dfepe)(η 2-H 2) ( 2b). Photolysis of a mixture of 2a and 2b in benzene resulted in complete conversion of 2a to 2b, which slowly thermally reconverted to an equilibrium mixture ( k ∼ 2.3 × 10 −4 s −1). The dihydrogen complex 2b reacts with N 2 gas to produce CpMn(dfepe)(N 2) ( 3) ( ν(N 2) = 2113 cm −1). Attempts to isolate 3 resulted in production of the corresponding N 2-bridged dimer, [CpMn(dfepe)] 2(μ-N 2) ( 4) (Raman: ν(N 2) = 2015 cm −1).