Wing-Por Leung

The first stable transition metal (molybdenum or tungsten) complexes having a metal–phosphorus(III) double bond: the phosphorus analogues of metal aryl- and alkyl-imides; X-ray structure of [Mo(η-C5H5)2(PAr)](Ar = C6H2But3-2,4,6)

Arylphosphinylidenemetal complexes [M(η-C5H5)2(PAr)][M = Mo (1) or W (2), Ar = C6H2But3-2,4,6] and an alkyl analogue [W(η-C5H5)2(PR)][R = CH(SiMe3)2(3)] have been prepared from [{M(η-C5H5)2HLi}4] and PCl2R′(R′= Ar or R), and show low-field 31P chemical shifts: δ(31P{1H})(C6D6)(1)+ 799.5 [J(31P–1H) 4 Hz (involving only one of the two C5H5 rings)]; (2)+666.1 [J(31P–183W) 153.5 Hz, J(31P–1H) 4 Hz]; and (3)+679.6 [J(31P–183W) 144.1 Hz]. Compound (1) has an Mo–P bond length of 2.370(2)A and a Mo–P–C bond angle of 115.8(2)°.

Synthesis of a germanium analogue of a dithiocarboxylic acid anhydride from the Ge(I) pyridyl-1-azaallyl dimer

The reaction of pyridyl-1-azaallyl germanium(ii) chloride RGeCl () [R = {N(SiMe(3))C(Ph)C(SiMe(3))(C(5)H(4)N-2)}] with lithium metal afforded the dimeric germanium(i) compound [(RGe)(2)] (); compound reacts with an excess of elemental sulfur to afford the novel germanium analogue of a dithiocarboxylic acid anhydride [{Ge(S)R}(2)S] () via the insertion of elemental sulfur into the Ge(i)-Ge(i) bond followed by the oxidative-addition of elemental sulfur to the germanium(ii) centres.

Photophysics and photochemical reactivities of organocopper(I) complexes. Crystal structure of [Cu2(PPh2Me)4(µ,η1-CCPh)2]

Dimeric [Cu2(PPh2Me)4(µ,η1-CCPh)2] has been synthesized and crystallographically characterized; its photophysics together with those of other related organocopper(I) complexes, [Cu2{2-C(SiMe3)2C5H4N}2] and [{Cu(C6H2Me3-2,4,6)}5] have been studied and Stern–Volmer quenching data of the phosphorescent state of the pyridine complex with organic halides are suggestive of a charge-transfer mechanism with a high driving-force regime.

Synthesis and characterisation of lanthanide(II) aryloxides including the first structurally characterised europium(II) compound [Eu(OC6H2But2-2,6-Me-4)2(thf)3]·thf (thf = tetrahydrofuran)

The lanthanide(II) aryloxide complexes [Yb(OC6H2But2-2,6-Me-4)2(OEt2)2]1, [Yb(OC6H3But2-2,6)2(thf)3]2, [Yb(OC6H2But3-2,4,6)2(thf)3]3, [Sm(OC6H2But2-2,6-Me-4)2(thf)3]4, [Eu(OC6H2But2-2,6-Me-4)2(thf)3]·thf 5, [Yb(OC6H2But2-2,6-Me-4)2(thf)3]6 and [Yb(OC6H2But2-2,6-Me-4)I(thf)x]7(thf = tetrahydrofuran) have been synthesized. Each of the complexes 1–3 was prepared by the reaction of 2 equivalents of the appropriate potassium aryloxide with Ybl2 in diethyl ether (1) or thf (2 or 3). Complexes 4–6 were prepared by the reaction of 2 equivalents of K(OC6H2But2-2,6-Me-4) with Lnl2(thf)2(Ln = Sm, Eu or Yb) in thf. Reacting Ybl2 with 1 equivalent of K(OC6H2But2-2,6-Me-4) in thf yielded complex 7 as the main product, but 171Yb-{1H} NMR spectroscopy showed that 6 and [Ybl2(thf)4]8 were also formed. The crystal structure of complex 5 reveals that it adopts a distorted trigonal-bipyramidal conformation with (i) apical thf oxygens [O(4)–Eu–O(5) 178.6(2)°, Eu–O(4) 2.590(5) and Eu–O(5) 2.573(5)A]; (ii) the equatorial O(1), O(2) and O(3) thf coplanar; and (iii) Eu–O(1) 2.321(5), Eu–O(2) 2.337(5) and Eu–O(3) 2.515(6)A. The crystal structure of complex 8 showed there to be an octahedral arrangement around the metal, the molecule lying on a crystallographic inversion centre, with angles I–Yb–O(1) 90.1(2), I–Yb–O(2) 91.4(2) and O(1)–Yb–O(2) 88.9(3)°, and bond lengths Yb–I 3.103(1), Yb–O(1) 2.399(9) and Yb–O(2) 2.373(8)A.

Synthesis and characterization of stannanechalcogenones; X-ray structures of [RN(RN)Sn(µ-S)]2 and [(RN)2SnE][RN= CH(SiMe3)C9H6N-8; E = Se, Te]

The tin(II) alkyl (R[graphic omitted] 1 [RN= CH(SiMe3)C9H6N-8] reacts with elemental chalcogens in thf to afford thermally stable dimeric dialkylstannane-thione [RN(R[graphic omitted](µ-S)]22 and monomeric dialkylstannane-selone and -tellurone [(R[graphic omitted]E](E = Se 3, Te 4) in good yields; 119Sn NMR spectra of 3 and 4 display satellites with coupling constants 1J119Sn–77Se 2966.3 Hz and 1J119Sn–125Te 7808.3 Hz; the tin–chalcogen distances from single-crystal X-ray analysis are 2.47 (av.), 2.398 and 2.618 A for 2, 3 and 4 respectively.

Axially asymmetric metal alkyls. Part 6. Lithiation of 2,2′-dimethyl-1,1′-binaphthyl and its trimethylsilylated compounds, and of 2,2′,6,6′-tetramethyl-1,1′-biphenyl (asymmetric induction): X-ray crystal structures of monomeric [{Li(Me2NCH2CH2NMe2)}2{(2-CH2C10H6)2}] and [Li{(Me2NCH2CH2)2NMe}{2-CH2-6-Me(C6H3)2-2′,6′-Me2}]

The compound [{Li(tmen)}2{(2-CH2C10H6)2}], (6)(tmen =N,N,N′,N′-tetramethylenediamine), has been prepared via metallation, and structurally characterized using X-ray diffraction data. It is monomeric with two different lithium centres, one bridging the ipso-carbon atoms at 2.13(5) and 2.23(5)A, the other interacting with one ipso-carbon at 2.36(5)A and its adjacent ring carbon at 2.51(5)A, such that one ipso carbon is bridging the lithium centres. 7Li N.m.r. data are consistent with this structure in toluene, below ca.–28 °C. Treatment of (6) with AsMe2I then Mel yielded the arsonium salt [(2-Me3AsCH2C10H6)2]I2, and with SiMe3Cl it gave (2-Me3SiCH2C10H6)2. This afforded [2-(Me3Si)2CHC10H6]2 on treatment with LiBun(tmen) then SiMe3Cl. Metallation of 2,2′,6,6′-Tetramethyl-1,1′-biphenyl using LiBun(pmdien)(pmdien =N,N,N′,N′,N″-pentamethyldiethylenetriamine) in diethyl ether yielded a monolithiated species [{Li(pmdien)}{2-CH2-6-Me(C6H3)2-2′,6′-Me2}](13), also structurally characterized; the lithium centre is attached to only the ipso-carbon of the hydrocarbyl group at 2.14(2)A. Treatment of the same biphenyl with LiBun(sp)[sp =(–)sparteine] in Et2O yielded a dilithiated species based on the asymmetrical chiral dianion, (2-CH2-6-MeC6H3)22–. The degree of asymmetric induction in the metallation step was estimated to be ca. 40% using a 1H n.m.r.–chiral lanthanide shift reagent technique on the diol (2-HOCH2CH2-6-MeC6H3)2, formed by carboxylation then esterification and reduction of the dilithiated species.

Novel monoanionic di-N,N′-centred chelating ligands and their C1 and C2 symmetrical zirconium complexes

Abstract The novel lithium complexes [Li{N(SiMe 3 )C(Ph)C(R)(C 5 H 4 N-2)}] 2 R = H or SiMe 3 ) and [Li{N(SiMe 3 )C(Ph)C(R)(C 5 H 4 N-2)} (R = H or SiMe 3 ), prepared from PhCN and [Li{C(SiMe 3 )(R)(C 5 H 4 N-2)}] 2 or [Li{C(SiMe 3 )(R)(C 5 H 4 N-2) react with ZrCl 4 to afford racemic complexes [Zr{N(SiMe 3 )C(Ph)C(R)(C 9 H 46N-2 )} 2 Cl 2 ] )R = H or SiMe 3 , 3b ) and [Zr{N(SiMe 3 )C(Ph)C(R)(C 5 H 4 N-2)} 2 Cl 2 ], respectively. Conproprotionation of ZrCl 4 and 3b or 4 afforded [Zr{N(SiMe 3 )C(Ph)C(SiMe 3 )(C 5 H 4 N-2)}Cl 3 ] and [Zr{N(SiMe 3 )C(Ph)C(SiMe) 3 (C 9 H 6 N-2)}Cl 2 ]. The compounds are characterized by NMR spectroscopy and X-ray data are provided for 3b .

Synthesis of α-, γ-phosphorus functionalized alkyl lithium species; X-ray structures of [{Li(L)(Ch2PMeR)}2][L =NNN′N′-tetramethylethylenediamine (tmen), R = Me or Ph; L =(–)sparteine, R = Ph] and [Li(tmen){CH(SiMe3)C6H4PPh2-o}]

[{Li(L)(CH2PMeR)}2][L = tetramethylethylenediamine (tmen), R = Me (1) or Ph (2); L =(–)-sparteine (sp), R = Ph (3)], prepared by treating the appropriate phosphine with LiBun(L) in hexane or diethyl ether, are dimeric in the solid. The phosphinomethyl ligands bridge the two lithium atoms as part of six-atom heterocycles; Li–C, P 2.145, 2.604; 2.14, 2.64; 2.20, 2.72A, respectively; (2) and (3) are homochiral and thus have a meso configuration. In benzene (1), (2), and [Li(tmen)(CH2PPh2)](5), are monomeric (cryoscopy), and 7Li–31P coupling only below ca. –70 °C for (1)–(3) and (5) in toluene (1 : 1 doublet, 7Li; 1 : 1 : 1 : 1 quartet, 31P, JLip 44.0–53.4 Hz) is consistent with the presence of symmetrical dimers of the type found in the solid for (1)–(3). [[graphic omitted]Ph2-o}], (4), similarly prepared, has the lithium as part of a chelate ring in the solid, binding through the ipso carbon and PIII centre; Li–C,P 2.25(1), 2.65(1)A. Trilithio species based on P(C6H4CHR–)3(R = H or SiMe3) are generated via metallation using LiBun(tmen). Treating the monolithio species derived from P(O)Me2Ph and LiBun(sp) with Etl yields P(O)MePhPrn of 14% estimated optical purity.

A dinuclear manganese(II) complex doubly bridged by skew-skew μ-carboxylato groups: synthesis and X-ray structure of [{Mn(bpy)2(p-Me2N+C5H4NCH2CO2−)}2] (ClO4)4

Abstract In the novel centrosymmetric dinuclear manganese(II) complex [{Mn(bpy)2(p-Me2N+C5H4NCH2 CO2−)}2](ClO4)4, the bridging betainee ligand functions in an abnormal non-planar skew-skew mode, with both MnII atoms lying on the same side of the mean plane of each bridging carboxylato group. The intramolecular metal-metal separation in the dinuclear cation agrees well with those in the range 4.64–4.79 A found for known doubly carboxylato-bridged manganese(II) complexes.

Synthesis and structures of the heavier alkali metal alkyls; the X-ray structures of [Na(µ-R)]∞ and [Rb(µ-R)(pmdeta)]2[R = CH(SiMe3)2, pmdeta =(Me2NCH2CH2)2NMe]

The crystalline, hexane-soluble metal alkyls [Na(µ-R)∞1, [KR(pmedta)]m, and [Rb(µ-R)(pmdeta)]22[R = CH(SiMe3)2, pmdeta =(Me2NCH2CH2)2NMe] have been prepared from LiR with equimolar portions of NaOBut, KOBut+ pmdeta, and Rb(OC6H2But2-2,6-Me-4)+ pmdeta, respectively; 1has chains of alternating cations and planar R– anions which are approximately orthogonal to the chains, (Na–C)av 2.555(10)A, (Na–C–H)av 76(3) and (Na–C–Na)av 152(1)°, whereas 2 consists of discrete dimers, (Rb–C)av 3.412(9)A, Rb–C–Rb 75.3(2) and C–Rb–C 104.7(2)°.