Tricarbonylbis trimethylphosphine iron

The reaction between 1.3 mL of FefCO), (9.69 x 10 mol) and 6.31 g of P(r-Bu)3 in 350 mL of dry cyclohexane (method 1) produces 475 mL of CO after 8 h of irradiation. The reaction mixture is filtered to yield 1.51 g of yellow product. An additional 1.05 g of solid is obtained by reducing the volume of solution. The combined yield (256 g) proves to be exclusively the monosubstituted product Apparently, the conditions of the reaction do not allow two bulky tri-tert-butylphosphine ligands to replace two carbonyl groups on Fe(CO)5. Yield 256 g 72%. 

Submitted by MICHEL O. ALBERS, ERIC SINGLETON, aod NEIL J. COVILLEf 

Checked by ARTHUR Y-J. CHEN, RUSTY BLANSKI.t and HERBERT D. KAESZ  

A recent review has highlighted the extensive and interesting chemistry of metal isocyanide complexes. Although synthetic procedures are varied, a vast number are based on substitution in metal carbonyl complexes by isonitriles. Such procedures are, however, not always successful. This is especially so in cases where multiple substitution of CO is required, as in the syntheses of homoleptic isocyanide complexes. Many of the inherent difficulties are illustrated by the reaction of iron pentacarbonyl with isocyanides. 

Pentacarbonyl iron is fairly inert to substitution reactions, and attempts to prepare Fe(CO)5 (CNR) (w = 1-5) by the direct reaction of Fe(CO)5 with isocyanides in Carius tubes has produced only the complexes Fe(CO)5 (CNR) (n = 1 and 2). The products were obtained as mixtures that required separation. Other syntheses, including photochemical and trimethylamine N-oxide-promoted displacement of carbonyl groups, or other means, give the same products in variable yidd. Procedures based on diiron nonacarbonyF and triiron dodecacarbonyl have produced similar results. The only zero-valent iron complex Fe(CO)s, (CNR), where n 2 is the complex FefCNR), prepared either by metal vapor synthesis techniques or by sodium amalgam reduction of iron(II) bromide in the presence of isocyanide.  

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Fe02S2C,H Iron, dicarbonyI(i -cyclopentadienyI)[(methyIthio)-tbiocarbonyl]-, 28 186 Fe03C9Hg, Iron, acetyIdicarbonyl(>) -cycIopentadienylK 26 239 Fe03P2C9Hi(, lron(0X tricarbonylbis-(trimethylphosphine)-, 28 177 Fe03P2C25Hj4, Iron(0X... 

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