L. Prasad

Assemblage of multimetal complexes using the diphosphoxane (POP) linkage

Abstract Heterobimetallic complexes can be prepared using the monodentate diphosphoxane ligand in Mo(CO)5PPh2OPPh2. Reactions with Cr(CO)5CH3CN and Fe2(CO)9 yielded the corresponding bimetallic products. The structure of Mo(CO)5PPh2OPPh2Fe(CO)4 was established by a single-crystal X-ray study. Cell data: Space group P 1 , monoclinic, a 10.533(2), b 10.993(2), c 16.439(3) A; α 97.86(2), β 92.34(1), γ 116.20(1)°; Z = 2, Dc 1.561 g cm−3 RF is 0.037 for 3830 observed reflections. The diphosphoxane ligand was found to bridge an octahedral Mo and the axial site of a trigonal bipyramidal Fe. Reaction of two equivalents of Mo(CO)5PPh2OPPh2 with (PhCN)2PdCl2 produced the trimetallic complex trans-PdCl2[PPh2OPPh2Mo(CO)5]2. The trimetallic complexes P[OPR2Mo(CO)5]3 were prepared from the reaction of PCl3 with Na[OPR2Mo(CO)5] (R = Ph, OEt). Similarly, a bimetallic complex PhP[OP(OEt)2Mo(CO)5]2 can be prepared from PhPCl2. These products illustrate the usefulness of the diphosphoxane linkage in the synthesis of multimetal complexes.

The crystal structure of dichlorodiethyl-3(2-pyridyl)-5,6-diphenyl-1,2,4-triazinetin(IV) ☆

C24H24N4Cl2Sn, monoclinic, Pn, a = 10.733(3), b = 22.979(5), c = 9.852(1) A, β = 93.82(1)°, Z = 4, Dcalc = 1.50 Mg·m−3. The structure was refined by block diagonal least squares to a residual of RF = 0.054 for 3336 observed reflections (I > 3σ(I)). Both the crystallographically unique molecules exhibit an octahedral coordination around the Sn atom with cis Cl atoms and trans ethyl groups. The conformation of the 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine moiety in the two molecules is different.

Diphosphine monoxide ligands: Complexes of tetraphenyldiphosphine oxide with group VIB metal carbonyls

Abstract Tetraphenyldiphosphine monoxide forms complexes of the type(CO)5M[PPh2P(O)Ph2] with Group VIB metals (M = Cr, Mo, W). The crystal and molecular structure of the Mo-complex has been determined:MoP2O6C29H20, Monoclinic Space Group P21/n,a 13.776(1),b 16.811(2),c12.162(1)A, β 90.36(1)°;Z = 4 and Dc 1.47 Mg m−3. RF is 0.038 for 5006observed reflections. The Mo atom is found to be coordinated to the originally trivalent phosphorusatom while the ligand P P bond remains intact and the oxygen atom isuncomplexed. The overall conformation around the P P bond is staggered. Heating of these complexes in diglyme resulted in loss of CO and tautomerization of the diphosphine oxide ligand into the chelatingdiphosphaxane in products identified as c i s − ( C O ) 4 M ( P P h 2 O ︹ P P h 2 ) . Reaction of excess OP2Ph4 with cis-(CO)4M(NHC5H10)2 yielded H-bonded heterocycles of the type c i s − ( C O ) 4 M [ P P h 2 O ( P P h 2 ) O ... H ︹ N C 5 H 10 ] which are inert towards displacement of the remaining piperidine ligand.