LINEARE OLIGOPHOSPHAALKANE. IX. TERTIAER-SEKUNDAERE METHYLENBISPHOSPHANE; NEUE BRUECKENLIGANDEN UND PHOSPHINIDENQUELLEN IN DER CLUSTERSYNTHESE

Article abstract of DOI:10.1016/0022-328X(85)87108-4

Methylene-bridged tertiary-secondary phosphanes R2PCH2PRH (R = i-Pr, CH2Ph, Me; Ia-Ic) react with excess diironenneacarbonyl to form the violet-coloured clusters Fe3(CO)9(μ₂-H)(μ₂-PRCH2PR2) (IIIa-IIIc).The crystal structure of the isopropyl derivative shows the Fe3-unit capped by the five-electron donor bridge RP(1)-CH2-P(2)R2 (Fe(1,2)-P(1) 2.1779(8), 2.194(1), Fe(3)-P(2) 2.293(1) Angstroem) while the μ-hydrogen atom is localized between iron atoms Fe(2) and Fe(3).At elevated temperatures, the P-C-P skeleton in IIIa-IIIb is cleaved, leading to PR2CH3-substituted μ₃-PR clusters Fe3(CO)9(PR2CH3)(μ₃-PR) (IVa, IVb) and subsequently to Fe3(CO)10(μ₃-PR) (Va, Vb).With Fe2(CO)9 in a 1/2 molar ratio the phosphanes Ia and Ib under mild pyrolytic conditions form the dihydro clusters Fe3(CO)8(μ₂-H)2(PR2CH3)(μ₃-PR) (VIa, VIb) in addition to Fe(CO)4(PR2CH3) and the cluster Fe3(CO)9(μ₃-PR)2 (VIIa, VIIb).