Synthesis and reactivity of iron nitrosyl hydrides substituted with triphenyl phosphine

Protonation of anion 1 [Fe(CO)3(NO)]−, (Na+) in the presence of P(C6H5)3 yielded the iron nitrosyl hydrides 3 FeH-(CO)2(NO)(P(C6H5)3) and 4 FeH(CO)(NO)(P(C6H5)3)2 or the iron nitrosyl cation 5 [Fe(CO)2(NO)(P(C6H5)3)2]+, [Formula: see text] de- pending upon the conditions. Anions 12 (Li+),[Fe(CO)(NO)(P(C6H5)3)2]− and 15 (Li+),[Fe(CO)2(NO)(P(C6H5)3)]− were formed in the reactions of Li+, −HB(C2H5)313 with hydrides 4 and 3 respectively. Anions 15 resulted also from the reaction of cation 5 with an excess (at least 6 equivalents) of boron hydride 13 and from the reaction of anion 12 with CO at atmospheric pressure. Hydrides 3 and 4 were prone to ligand exchange reactions and could be interconverted easily. This is in contrast to the reluctance of the isoelectronic cobalt hydride CoH(CO)3(P(C6H5)3) to undergo further reaction with P(C6H5)3. Another striking difference between the iron nitrosyl hydrides and the isoelectronic cobalt carbonyl hydrides was found when the reactions which normally yield bimetallic derivatives were investigated. The nature of the decomposition products formed in the thermolysis of 3 and 4, in the reactions of 3 with olefins and dioxygen, and in the reduction reactions of cation 5 suggests that metallic dimers containing a (Fe(NO))2 unit are prone to fast CO and NO exchanges triggering an irreversible fragmentation into monometallic decomposition products, comprising invariably iron dinitrosyl derivatives.