Lineare oligophosphaalkane, xxvii [1] fragmentierung und zyklisierun^ disekundarer methylenbisphosphane mit sperrigen aromatischen resten in fe3- und ru3-clustern linear oligophosphaalkanes, xxvii [1] fragmentation and cyclization of disecondary methylenebisphosphanes with bulky aromatic substituents in fe3 and ru3 clusters

Abstract

On reaction of disecondary methylenebisphosphanes H (R)P-CH2-P(R)H and H(tBu)P-CH2-P(R)H(R = Ph, 2,4,6-R'3C6H2, R' = Me, Et, iPr, tBu) with excess Fe2(CO)9, Ru3(CO)12 and Os3(CO)12 the hydrido clusters M3(CO)9(μ2-H )[μ2-P(R, tBu)-CH2-P(R,tBu)H] (M = Fe, Ru, Os) (3a -3j) are formed in addition to bimetallic phosphido com plexes (5a -5g) and clusters (4a - 4f) with [μ2-P(R,tBu)]2CH2 bridges. At higher temperatures cleavage of the P-C-P skeleton in 3a, 3b, 3d and 3h is accompanied by activation of the terminal C-H bonds of ortho-substituents R' (Et, iPr, tBu), phosphinidene clusters (8a, 8b, 8d and 8e) containing 2,3-dihydrobenzo[b]phosphole ligands being formed. Cluster com pounds Fe3(CO)9[μ3-P(R, tBu)][MeP(H)R] (7a - 7c) with secondary phosphane ligands could be identified as intermediate products. The X-ray structural analysis of Fe3(CO)8(μ2-H)2L(L = 1,3,3-trirnethyl-6,8-di-tert-butyl-2,3-dihydrobenzo[b]phosphole) (8e) shows a trigonal pyramidal Fe3P skeleton with the 2,3-dihydrobenzo[b]phosphole ligand in axial position. Metal-assisted fragmentation of the methylenebisphosphanes H(R )P-CH2-P(R)H(1f, 1g) with less bulky aromatic substituents (R = Ph, 2,4,6-Me3C6H2) affords bis-μ3-phosphinidene clusters Fe3(CO)9(μ3-PR)(μ3-PR') 11e (R = R' = 2,4,6-Me3C6H2) or 11f (R' = Ph, R = Me) and the phosphaalkene cluster Fe3(CO)9(μ3-PPh)(μ3, η2-P(Ph)=CH2) (13b), respectively. If 1g is treated with Fe2(CO)9 in an 1:2 molar ratio at elevated temperatures cleavage of the P-C-P skeleton leads to 14, a bimetallic complex with different phosphido bridges [μ2-P(R )H and μ2-P(R)Me]