LINEARE OLIGOPHOSPHAALKANE XIII.TRIPHOSPHAALKANE MIT DEM P-C-P-C-P-DONORSKELETT; LIGANDEN FUER DEN AUFBAU VON MEHRKERNKOMPLEXEN

Article abstract of DOI:10.1016/0022-328X(85)80372-7

The triphosphaalkane Cl2PCH2PClCH2PCl2 (III) is formed as a by-product in the synthesis of Cl2PCH2PCl2 (II).On treating III with MeMgCl or EtOH (in the presence of a base), the methyl or ethoxy derivative (V or VI) may be obtained in satisfactory yields.With Ni(CO)4 or Fe2(CO)9 V forms trinuclear complexes <(CO)_nM>PMe2CH2PMen>CH2PMe2n> (X, XIII; M = Fe, Ni; n = 4, 3) or binuclear stable six-membered chelate ring systems n>PMe(CH2PMe2)2m> (IX, XIV; M = Fe, Ni; n = 4, 3; m = 3, 2).An excess of Fe2(CO)9 (molar ratio V/Fe2(CO)9 1/5) yields XI with an Fe-Fe bond or the cluster XII, respectively.In both cases V bridges the Fe-Fe bond with a P-C-P donor set.X-ray structural analysis of X (triclinic, space group P1) exhibits a staggered arrangement of the three metal carbonyl fragments bound to the "stretched" P-C-P-C-P skeleton of V (Fe(1)-P(1) 2.236(1), Fe(2)-P(2) 2.226(1), Fe(3)-P(3) 2.231(1) Angstroem, P(1)-C(13)-P(2) 126.7(1), P(2)-C(14)-P(3) 127.6(1) deg).In XI (monoclinic, space group P2₁/n) one P-C-P donor set together with the two iron atoms Fe(2) and Fe(3) form a stable five-membered Fe2P2C ring (Fe(2)-Fe(3) 2.705(1), Fe(2)-P(2) 2.251(1), Fe(3)-P(3) 2.239(1) Angstroem).The third phosphorus atom P(1) binds an Fe(CO)4 group (Fe(1)-P(1) 2.245(1) Angstroem).The structure of cluster compound XII (monoclinic, space group P2₁/n) is derived from that of Os3(CO)12.One P-C-P donor set of V replaces two CO groups in equatorial positions, forming a stable Fe2P2C five-membered ring.The remaining donor position of V coordinates with an Fe(CO)4 group.