Reactions of mononuclear transition metal carbonyl complexes with hydride donors. The reduction of coordinated carbon monoxide and a convenient synthesis of formyltetracarbonylferrate(O)salts

Abstract

The reactions of Fe(CO) 5, Fe(CO) 4P(C 6H 5) 3, M(CO) 6 (M  W, Mo, Cr), and (CH 3C 5H 4Mn(CO) 3 with KH and several boron and aluminium hydrides were investigated. Iron pentacarbonyl was converted quantitatively to K +Fe(CO) 4-(CHO) by hydride transfer from KBH(OCH 3) 3 allowing isolation of [P(C 6H 5) 3] 2-N n+Fe(CO) 4(CHO) − in 50% yield. Lower yields were obtained with LiBH(C 2H 5) 3, and other hydride sources gave little or no formyl product. The stability of Fe(CO) 4(CHO) − in THP was found to depend on the cation, decreasing in the order [P(C 6H 5) 3] 2N + > K + > Na + > Li +. No formyl complexes were isolated and no spectroscopic evidence for formyl formation was observed in the reactions of the other transition metal carbonyls with several hydride sources. Fe(CO) 4-P(C 6H 5) 3 gave K 2Fe(CO) 4 when treated with KHB(OCH 3) 3. When treated with LiBH(C 2H 5) 3, W(CO) 6 gave a mixture of HW 2(CO) 10 −and (OC) 5W(COC 2H 5) −; the latter was methylated to give the carbene complex (OC) 5WC(OCH 3)C 2H 5.