Coordinatively Unsaturated Diiron Complexes: Synthesis and Crystal Structures of [Fe_2(CO)_4(#mu#-H)(#mu#-P~tBu_2)(#mu#-Ph_2PCH_2PPh_2)] and [Fe_2(CO)_4(#mu#-CH_2)(#mu#-H)(#mu#-P~tBu_2)(#mu#-Ph_2PH_PPh_2)

摘要

[Fe_2(#mu#-CO)(CO)_6(#mu#-H)(#mu#-P~tBu_2)] (1) reacts spontaneously with dppm (dppm = Ph_2PCH_2PPh_2) to give [Fe_2](#mu#-CO)(CO)_4(#mu#-H)(#mu#-P~tBu_2)(#mu#-dppm)] (2c). By thermolysis or photolysis, 2c loses very easily one carbonyl ligand and yields the corresponding electronically and coordinatively unsaturated complexs [Fe_2(CO)_4(#mu#-H)(#mu#-P~tBu_2)(#mu#-dppm)] (3). 3 exhibits a Fe-Fe double bond which could be confirmed by the addition of methylene to the corresponding dimetallacyclopropane [Fe_2(CO)_4(#mu#-CH_2)(#mu#-H)(#mu#-P~tBu_2)(#mu#-dppm)] (4) . The reaction of 1 with dppe (Ph_2PC_2H_4PPh_2) affords [Fe_2(#mu#-CO)(CO)_4(#mu#-H)(#mu#-P~tBu_2)(#mu#-dppe)] (5). In contrast to the thermolysis of 2c, yielding 3, the heating of 5 in toluene leads rapidly to complete decomposition. The reaction of 1 with PPh_3 yields[Fe_2(CO)_6(H)(#mu#-P~tBu_2)(PPh_3)] (6a), while with ~tBu_2PH the compound [Fe_2(#mu#-CO)(CO)_5(#mu#-H)(#mu#-P~tBu_2)(~tBu_2PH)] (6b) is formed. The thermolysis of 6b affords [Fe_2(CO)_5(#mu#-P~tBu_2)_2] and the degradation products [Fe_2(CO)_3(~tBu_2PH)_2] and [Fe(CO)_4(~tBu_2PH)]. The molecular structures of 3, 4 and 6b were determined by X-ray crystal structure analyses.