‘User-friendly’ primary phosphines and an arsine: synthesis and characterization of new air-stable ligands incorporating the ferrocenyl group

Abstract

Reaction of FcCH 2CH 2P(O)(OH) 2 or FcCH 2P(O)(OH)(OEt) [Fc=Fe(η 5-C 5H 4)(η 5-C 5H 5)] with excess CH 2N 2 followed by reduction with Me 3SiCl–LiAlH 4 gives the air-stable primary phosphines FcCH 2CH 2PH 2 and the previously reported analogue FcCH 2PH 2 in high yields. Reduction of 1,1′-Fc′[CH 2P(O)(OEt) 2] [Fc′=Fe(η 5-C 5H 4) 2] and 1,2-Fc″[CH 2P(O)(OEt) 2] [Fc″=Fe(η 5-C 5H 5)(η 5-C 5H 3)] similarly gives the new primary phosphines 1,1′-Fc′(CH 2PH 2) 2 and 1,2-Fc″(CH 2PH 2) 2, respectively. The arsine FcCH 2CH 2AsH 2, which is also air-stable, has been prepared by reduction of the arsonic acid FcCH 2CH 2As(O)(OH) 2 using Zn/HCl. An X-ray structure has been carried out on the arsine, which is only the second structure determination of a free primary arsine. The molybdenum carbonyl complex [1,2-Fc″(CH 2PH 2) 2Mo(CO) 4] was prepared by reaction of the phosphine with [Mo(CO) 4(pip) 2] (pip=piperidine), and characterized by a preliminary X-ray structure determination. However, the same reaction of 1,1′-Fc′(CH 2PH 2) 2 with [Mo(CO) 4(pip) 2] gave [1,1′-Fc′(CH 2PH 2) 2Mo(CO) 4] and the dimer [1,1′-Fc′(CH 2PH 2) 2Mo(CO) 4] 2, characterized by electrospray mass spectrometry. 1,1′-Fc′[CH 2PH 2Mo(CO) 5] 2 and 1,2-Fc″[CH 2PH 2Mo(CO) 5] 2 were likewise prepared from the phosphines and excess [Mo(CO) 5(THF)].