Devon W. Meek

Syntheses of new tetrafluoroaryl derivatives of phosphorus and sulfur

Abstract A number of polydentate phosphorus and sulfur ligands, containing one or two 1,2,3,4-tetrafluorophenyl connecting groups, were readily synthesised from the lithium derivatives of diphenyl( o -bromotetrafluorophenyl)phosphine and 2,3,4,5tetrafluorothioanisole. The latter molecules were prepared from the monolithium derivatives of 1,2-dibromotetrafluorobenzene and 1,2,3,4-tetrafluorobenzene, respectively.

Five-coordinate cobalt(II), four- and five-coordinate nickel(II), and six-coordinate cobalt(III) complexes of the flexible diphosphine ligand 1,3-bis(dimethylphosphino)propane☆☆☆

Abstract The flexible, aliphatic, diphosphine ligand (CH3)2PCH2CH2CH2P(CH3)2, dmp, forms the five-coordinate complexes [M(dmp)2X]+ (M = Ni, X = Cl, Br, I, NCS; M = Co, X = Cl, Br, I), as well as the four-coordinate, planar Ni(dmp)X2 and six-coordinate trans-[Co(dmp)2X2]+ complexes. In the case of nickel cyanide, the only isolatable five-coordinate compound corresponded to the dinuclear Ni2(dmp)3(CN)4, which contains a bridging diphosphine ligand. All of the complexes were characterized by elemental analyses and by conductance, magnetism, infrared, and electronic spectral measurements. In the five-coordinate nickel series [Ni(dmp)2X]+, the bromide and iodide complexes appear to possess trigonal-bipyramidal structures, whereas the analogous chloride and thiocyanate complexes have distorted structures of approximately Cs microsymmetry.

Structural and stereochemical studies on reactive iridium(III) dihydride complexes of the triphosphine ligand C6H5P[CH2CH2CH2P(C6H11)2]2

Abstract The iridium(III) dihydride complexes IrH2X- (Cyttp) (X = Cl, I) possess a mer-octahedral structure in which the hydrides are cis to each other and the Cyttp ligand is chelated around an edge of the octahedron. The phenyl group on the central phosphorus atom is oriented away from the chloride ligand in the crystal structure, and Nuclear Overhauser Effect (NOE) measurements show that this anti coordination geometry is maintained in solution. Treatment of IrH2Cl(Cyttp), 1a, with TIBF4 and CH3CN results in a mixture of anti and syn diastereomers, whereas CO gives only the syn diastereomer of the type [IrH2(CH3CN)(Cyttp)]+ and Tl+.

FOUR- AND FIVE-COORDINATE NICKEL(II) COMPLEXES OF THE ALIPHATIC, TRIDENTATE LIGANDS BIS(3-DIMETHYLARSINOPROPYL)METHYLARSINE AND BIS(3-DIMETHYLARSINOPROPYL)PHENYLPHOSPHINE

Abstract Fifteen diamagnetic nickel(II) complexes of the flexible, tridentate ligands bis(3-dimethylarsinopropyl)phenyl-phosphine(dap) and bis(3-dimethylarsinopropyl)methylarsine(tas) were isolated and characterized. The molecular, five-coordinate complexes Ni(ligand)X 2 (ligand=dap; X=Cl, Br, I, NCS, CN: ligand=tas; X=Br, I, NCS, CN) and the four-coordinate complexes [Ni(dap)Cl]ClO4 and [Ni(dap)NO3]NO3 were studied by electronic and infrared spectra, magnetic, conductivity, and molecular weight measurements. On the basis of X-ray structural determinations of Ni(tas)Br2 and Ni(dap)(CN)2·H2O and the similar electronic spectra of the dap and tas series of complexes, the inner coordination geometry of all these complexes can be represented as a distorted square pyramid. The method of isolation and the properties of the polynuclear complexes [Ni2L3(H2O](ClO4)4 (L=dap and tas) and [Ni3(dap)3I5]B(C6H5)4 are also discussed.

PLATINUM(II) COMPLEXES OF THE TRIDENTATE LIGAND 1,1,1-TRIS(DIPHENYLPHOSPHINOMETHYL)ETHANE. TRANS INFLUENCE STUDIES AND DETECTION OF LINKAGE ISOMERS OF THIOCYANATE BY 31P NMR IN PTX2(TRIPHOS) COMPLEXES

Abstract Two series of complexes [PtX2(triphos)] (X=Cl, Br, I, CH3, C6H5, CN, thiocyanate; triphos=1,1,1-tris(diphenylphosphino-methyl)ethane) and [PtX2(dpp)] (X = Cl, CN, thiocyanate; dpp = 1,3-bis(diphenylphosphino)propane) have been prepared, and their structures have been established on the basis of 31P NMR spectroscopy. A definitive trans influence order is found: CH3 > C6H5 > CN > SCN > I > NCS > Br > Cl. For the thiocyanate complexes, all three possible linkage isomers are observed and assigned from 31P NMR spectroscopy. The [Pt(thiocyanate)2(triphos)] complex is fluxional at room temperature. Isomerization is believed to occur by a non-dissociative process.

Isomerization of RuCl2(Cyttp) (Cyttp=C6H5P(CH2CH2CH2P(C6H11)2)2) in solution

The structure of RuCl 2 (Cyttp) (Cyttp=C 6 H 5 P(CH 2 CH 2 CH 2 P(C 6 H 11 ) 2 ) 2 ) in solution is very dependent on the polarity and coordination ability of the solvents. In non-polar solvents such as benzene, mer -RuCl 2 (Cyttp) and fac -RuCl 2 (Cyttp) are present in about equal quantity. In halogenated solvents (such as dichloromethane, chloroform, CDCl 2 CDCl 2 ), three isomers are present: fac -RuCl 2 (Cyttp) (predominant), [Ru 2 Cl 3 (Cyttp) 2 ]Cl (minor) and mer -RuCl 2 (Cyttp) (trace). In other polar solvents such as CD 3 COOD and CD 3 NO 2 the ionic dinuclear complex [Ru 2 Cl 3 (Cyttp) 2 ]Cl is the major species along with fac -RuCl 2 (Cyttp). In methanol, only [Ru 2 Cl 3 (Cyttp) 2 ]Cl is present. Acetonitrile complexes are formed when RuCl 2 (Cyttp) is treated with acetonitrile. The X-ray structure of fac -RuCl 2 (Cyttp) has been determined in space group P 2 1 / n with cell parameters a =11.912(4), b =11.953(2), c =31.303(8) A, β=94.32(2)°, V =4444 A 3 , Z =4, R =0.042 and R w =0.050 for the 4985 intensities with F 0 2 > 3σ( F o 2 ) and the 439 variables.

Synthesis of polytertiary phosphines and ‘mixed’ phosphorus–sulphur and ‘mixed’ phosphorus–nitrogen polydentate ligands via free-radical catalysis

In the presence of free radicals, phosphorus–hydrogen and sulphur–hydrogen bonds cleanly and readily add to the carbon–carbon double bonds of vinyl derivatives to produce organic compounds that are useful as polydentate chelating ligands. The generality and mild conditions of the reaction are demonstrated by the synthesis of di-, tri-, and tetra-(tertiary phosphines) and of compounds that contain both phosphorus and sulphur or phosphorus and nitrogen donor groups. This free-radical-catalysed addition of molecules containing P–H and S–H bonds to vinyl compounds provides a general valuable alternative to the base-catalysed addition method.

Trigonal-bipyramidal nickel(II) complexes of tris(3-dimethylarsinopropyl)stibine

Abstract Trigonal-bipyramidal complexes [Ni(ligand)X]B(C6H5)4 (X=Cl, Br, I, NCS, NO3, CN) of the new flexible, quadridentate stibine ligand Sb[CH2CH2Ch2AS - (CH3)2]3 were prepared and characterized by analyses and by spectral, magnetic, and conductivity measurements. Electronic spectra of three series of trigonal-bipyramidal complexes of the ligands D[CH2CH2CH2As(CH3)2]3 (D=P, As, Sb) show that the normal spectrochemical series P>As>Sb is obtained for the cyanide and chloride complexes, in constrast to the anomalous spectrochemical ord P>As>Sb that was observed by Higginson, McAuliffe, and Venanzi8 with the rigid o-phenylene ligands (o-Ph2L-C6H4)3L′ (L= P and As; L′=P, As, and Sb). The present study with Sb[CH2CH2CH2As(CH3)2]3 provides confirmatroy evidence for a compression effect in the nickel(II) complexes of the rigid ligand Sb(o-C6H4LPh2)3.

Synthesis of polyphosphine ligands containing trimethylene linkages and platinum(II)-polyphosphine complexes

Abstract The addition of lithium diisopropylamide (LDA) to solutions of 1-bromo-3- chloropropane and a primary or secondary phosphine in THF at − 78°C provides a new, inexpensive and time efficient method for the synthesis of high-purity 3-chloropropyl- phosphines in high yield. The monophosphine intermediate C 6 H 5 P[CH 2 CH 2 CH 2 Cl] 2 was used for the synthesis of the known chelating triphosphine ligands C 6 H 5 P[CH 2 CH 2 CH 2 P(C 6 H 5 ) 2 ] 2 (ttp) and C 6 H 5 P[CH 2 CH 2 CH 2 P(C 6 H 11 ) 2 ] 2 (Cyttp). This method was extended to the synthesis of two new polyphosphine ligands that contain electronwithdrawing groups, i.e. ( p -CF 3 C 6 H 4 ) 2 PCH 2 CH 2 CH 2 P(H)C 6 H 5 (CF 3 PPH) and C 6 H 5 P [CH 2 CH 2 CH 2 P( p -CF 3 C 6 H 4 ) 2 ] 2 (CF 3 ttp). Platinum(II) complexes of CF 3 PPH and CF 3 ttp were synthesized and the spectral properties of these complexes are compared to known platinum(II) complexes.

Four- and five-coordinate nickel(II) complexes of the flexible triphosphine bis(2-diphenylphosphinoethyl)phenylphosphine

Abstract The preparation of the ligand and the nickel complexes of the formulation Ni(DPP)X 2 , where DPP is the new flexible triphosphorous ligand bis(2-diphenylphosphinoethyl)phenylphosphine, [C 6 H 5 ) 2 PCH 2 CH 2 ] 2 PC 6 H 5 , and X is Cl − , Br − , I − , NCS − , or CN − , is described. Except for the Ni(DPP)(CN) 2 complex, which is a non-conductor in acetonitrile, the above complexes behave as uni-univalent electrolytes in acetonitrile. The implied existence of the cation, [Ni(DPP)X] + , is confirmed by the isolation of the complexes [Ni(DPP)X]B(C 6 H 5 ) 4 , when equimolar amounts of the above nickel complexes and sodium tetraphenylborate are mixed in hot ethanol. The visible electronic absorption spectra of the two series of complexes [Ni(DPP)X]B(C 6 H 5 ) 4 and Ni(DPP)X 2 in acetonitrile solution are quite similar, and are indicative of Ni II in a planar, four-coordinate environment. Electronic spectra of the solid complexes Ni(DPP)X 2 , taken at both 300°K and 77°K, show two ligand field bands in the visible region. These spectra are discussed in terms of five-coordinate structures in the solid state. The cyanide complex, Ni(DPP)(CN) 2 , appears to be five-coordinate both in the solid state and in solution.