LINEAR OLIGOPHOSPHAALKANES .26. FUNCTIONA LIZED PRIMARY PHOSPHINES INCLUSTER SYNTHESIS - METAL-ASSISTED FRAGMENTATION OF PH2P-CH2-PH2

On reaction with diironenneacarbonyl the tertiary primary phosphine Ph 2PCH2PH2 yields the hydrido cluster (mu2-H)(mu2-PHCH2PPh2)Fe3(CO)9 (4) . If excess of Fe2(CO)9 is employed in this reaction the P-C-P-bridged Fe4-cluster 5 is formed with loss of hydrogen. At higher temperatures rearrangement of the Fe3(Fe)P-skeleton and phosphinidene fragmentatio n of the P-C-P backbone of 5 affords the Fe4P spiro compound (mu4-P)(m u2, eta2-PPh2CH2)Fe4(CO)14 (6) with an edge bridging Ph2-CH2 unit. X-r ay structural analysis of 6 (space group P2(1)/n) reveals a distorted Fe4P spiro type arrangement. The iron atoms Fe(1) and Fe(3) and the Ph 2PCH2 ligand with a short P-C bond (P(1)-C(1) 178.6(7) pm) form a dist orted almost planar four-membered Fe2PC ring system.