Synthesis, structures and reactions of lithium complexes of [(o-RCHC6H4)PPh2=NSiMe3]-(R = H, SiMe3) ligands

N-Trimethylsilyl o-methylphenyldiphenylphosphinimine, (o-MeC6H4)PPh2=NSiMe3 (1), was prepared by reaction of Ph2P(Br)=NSiMe3 with o-methylphenyllithium. Treatment of 1 with LiBun and then Me3SiCl afforded (o-Me3SiCH2C6H4)PPh2=NSiMe3 (2). Lithiations of both 1 and 2 with LiBu(n) in the presence of tmen gave crystalline lithium complexes [Li{CH(R)C6H4(PPh(2=NSiMe3)-.tmen](3, R = H; 4, R = SiMe3). From the mother liquor of 4, traces of the tmen-bridged complex [Li{CH(SiMe3)C6H4(PPh2=NSiMe3)-2}]2(mu-tmen) (5) were obtained. Reaction of 2 with LiBun in Et2O yielded complex [Li{CH(SiMe3)C6H4(PPh2=NSiMe3)-2}.OEt2] (6). Reaction of lithiated with Me2SiCl2 in a 2:1 molar ratio afforded dimethylsilyl-bridged compound Me2Si[CH2C6H4(PPh2=NSiMe3)-2]2 (7). Lithiation of 7 with two equivalents of LiBun in Et2O yielded [Li2{(CHC6H4(PPh2=NSiMe3)-2)2SiMe2}.0.5OEt2](8.0.5OEt2). Treatment of 4 with PhCN formed a lithium enamide complex [Li{N(SiMe3)C(Ph)CHC6H4(PPh2=NSiMe3)-2}.tmen] (9). Reaction of two equivalents of 5 with 1,4-dicyanobenzene gave a dilithium complex [{Li(OEt2)2}2(1,4-{C(N(SiMe3)CHC6H4(PPh2=NSiMe3)-2}2C6H4)] (10). All compounds were characterised by NMR spectroscopy and elemental analyses. The structures of compounds 2, 3, 5, 6 and 9 have been determined by single crystal X-ray diffraction techniques.     

Synthesis and structures of the [benzamidinato]3- complexes Li3(tmeda)(L1)]2 and [Li(thf)4][Li5(L2)(OEt2)2] [L1 = N(SiMe3)C(Ph)N(SiMe3) and L2 = N(SiMe3)C(C6H4-4)NPh

Reduction at ambient temperature of each of the lithium benzamidinates [Li(L(1))(tmeda)] or [{Li(L(2))(OEt(2))(2)}(2)] with four equivalents of lithium metal in diethyl ether or thf furnished the brown crystalline [Li(3)(L(1))(tmeda)] (1) or [Li(thf)(4)][Li(5)(L(2))(2)(OEt(2))(2)] (2), respectively. Their structures show that in each the [N(R(1))C(R(3))NR(2)](3-) moiety has the three negative charges largely localised on each of N, N' and R = Aryl); a consequence is that the "aromatic" 2,3- and 5,6-CC bonds of R(3) approximate to being double bonds. Multinuclear NMR spectra in C(6)D(6) and C(7)D(8) show that 1 and 2 exhibit dynamic behaviour. [The following abbreviations are used: L(1) = N(SiMe(3))C(Ph)N(SiMe(3)); L(2) = N(SiMe(3))C(C(6)H(4)Me-4)N(Ph); tmeda = (Me(2)NCH(2)-)(2); thf = tetrahydrofuran.] This reduction is further supported by a DFT analysis.     

Formation of the imide [Ta(NMe2)3(μ-NSiMe3)]2 through an unprecedented α-SiMe3 abstraction by an amide ligand

Ta(NMe(2))(4)[N(SiMe(3))(2)] (1) undergoes the elimination of Me(3)Si-NMe(2) (2), converting the -N(SiMe(3))(2) ligand to the ═NSiMe(3) ligand, to give the imide "Ta(NMe(2))(3)(═NSiMe(3))" (3) observed as its dimer 4. CyN═C═NCy captures 3 to yield guanidinates Ta(NMe(2))(3-n)(═NSiMe(3))[CyNC(NMe(2))NCy](n) [n = 1 (5), 2 (6)]. The kinetic study of α-SiMe(3) abstraction in 1 gives ΔH(?) = 21.3(1.0) kcal/mol and ΔS(?) = -17(2) eu.     

Extremely bulky amido-group 14 element chloride complexes: potential synthons for low oxidation state main group chemistry

The preparation of a series of extremely bulky secondary amines, Ar*N(H)SiR(3) (Ar* = C(6)H(2){C(H)Ph(2)}(2)Me-2,6,4; R(3) = Me(3), MePh(2) or Ph(3)) is described. Their deprotonation with either LiBu(n), NaH or KH yields alkali metal amide complexes, several monomeric examples of which, [Li(L){N(SiMe(3))(Ar*)}] (L = OEt(2) or THF), [Na(THF)(3){N(SiMe(3))(Ar*)}] and [K(OEt(2)){N(SiPh(3))(Ar*)], have been crystallographically characterised. Reactions of the lithium amides with germanium, tin or lead dichloride have yielded the first structurally characterised two-coordinate, monomeric amido germanium(II) and tin(II) chloride complexes, [{(SiR(3))(Ar*)N}ECl] (E = Ge or Sn; R = Me or Ph), and a chloride bridged amido-lead(II) dimer, [{[(SiMe(3))(Ar*)N]Pb(μ-Cl)}(2)]. DFT calculations on [{(SiMe(3))(Ar*)N}GeCl] show its HOMO to exhibit Ge lone pair character and its LUMO to encompass its Ge based p-orbital. A series of bulky amido silicon(IV) chloride complexes have also been prepared and several examples, [{(SiR(3))(Ar*)N}SiCl(3)] (R(3) = Me(3), MePh(2)) and [{(SiMe(3))(Ar*)N}SiHCl(2)], were crystallographically characterised. The sterically hindered group 14 complexes reported in this study hold significant potential as precursors for kinetically stabilised low oxidation state and/or low coordination number group 14 complexes.     

Reactions of Li- and Yb-coordinated N,N'-bis(trimethylsilyl)-beta-diketiminates: one- and two-electron reductions, deprotonation, and C-N bond cleavage

The synthesis and characterisation of novel Li and Yb complexes is reported, in which the monoanionic beta-diketiminato ligand has been (i) reduced (SET or 2 [times] SET), (ii) deprotonated, or (iii) C-N bond-cleaved. Reduction of the lithium beta-diketiminate Li(L(R,R'))[L(R,R')= N(SiMe(3))C(R)CHC(R')N(SiMe(3))] with Li metal gave the dilithium derivative [Li(tmen)(mu-L(R,R'))Li(OEt(2))](R = R'= Ph; or, R = Ph, R[prime or minute]= Bu(t)). When excess of Li was used the dimeric trilithium [small beta]-diketiminate [Li(3)(L(R,R[prime or minute]))(tmen)](2)(, R = R'= C(6)H(4)Bu(t)-4 = Ar) was obtained. Similar reduction of [Yb(L(R,R'))(2)Cl] gave [Yb[(mu-L(R,R'))Li(thf)](2)](, R = R[prime or minute]= Ph; or, R = R'= C(6)H(4)Ph-4 = Dph). Use of the Yb-naphthalene complex instead of Li in the reaction with [Yb(L(Ph,Ph))(2)] led to the polynuclear Yb clusters [Yb(3)(L(Ph,Ph))(3)(thf)], [Yb(3)(L(Ph,Ph))(2)(dme)(2)], or [Yb(5)(L(Ph,Ph))(L(1))(L(2))(L(3))(thf)(4)] [L(1)= N(SiMe(3))C(Ph)CHC(Ph)N(SiMe(2)CH(2)), L(2)= NC(Ph)CHC(Ph)H, L(3)= N(SiMe(2)CH(2))] depending on the reaction conditions and stoichiometry. The structures of the crystalline complexes 4, 6x21/2(hexane), 5(C(6)D(6)), and have been determined by X-ray crystallography (and have been published).     

Synthesis and characterization of three-coordinate and related beta-diketiminate derivatives of manganese,iron, and cobalt

Treatment of M[N(SiMe(3))(2)](2) (M = Mn, Fe, Co) with various bulky beta-diketimines afforded a variety of new three-coordinate complexes which were characterized by UV-vis, (1)H NMR and IR spectroscopy, magnetic measurements, and X-ray crystallography. Reaction of the beta-diketimine H(Dipp)NC(Me)CHC(Me)N(Dipp) (Dipp(2)N(wedge)NH; Dipp = C(6)H(3)-2,6-Pr(i)(2)) with M[N(SiMe(3))(2)](2) (M = Mn or Co) gave Dipp(2)N(wedge)NMN(SiMe(3))(2) (M = Mn, 1; Co, 3) while the reaction of Fe[N(SiMe(3))(2)](2) with Ar(2)N(wedge)NH (Ar = Dipp, C(6)F(5), Mes, C(6)H(3)-2,6-Me(2), or C(6)H(3)-2,6-Cl(2)) afforded the series of iron complexes Ar(2)N(wedge)NFe[N(SiMe(3))(2)] (Ar = Dipp, 2a; C(6)F(5), 2b; Mes, 2c; C(6)H(3)-2,6-Me(2), 2d; C(6)H(3)-2,6-Cl(2), 2e). This represents a new synthetic route to beta-diketiminate complexes of these metals. The four-coordinate bis-beta-diketiminate complex Fe[N(wedge)N(C(6)F(5))(2)](2), 4, was also isolated as a byproduct from the synthesis of 2b. Direct reaction of the Dipp(2)N(wedge)NLi with CoCl(2) gave the "ate" salt Dipp(2)N(wedge)NCoCl(2)Li(THF)(2), 5, in which the lithium chloride has formed a complex with Dipp(2)N(wedge)NCoCl through chloride bridging. The Fe(III) species Dipp(2)N(wedge)NFeCl(2), 6, was obtained cleanly from the reaction of FeCl(3) with Dipp(2)N(wedge)NLi. Magnetic measurements showed that all the complexes have a high spin configuration. The different substituents in the series of iron complexes 2a-e allowed assignment of their paramagnetically shifted (1)H NMR spectra. The X-ray crystal structures 1-2d and 3 showed that they have a distorted three-coordinate planar configuration at the metals whereas complexes 4-6 have highly distorted four-coordinate geometries.     

Facile synthesis of cyclopropene analogues of aluminum and an aluminum pinacolate, and the reactivity of LAl[eta(2)-C(2)(SiMe(3))(2)] toward unsaturated molecules (L=HC[(CMe)(NAr)](2), Ar=2,6-i-Pr(2)C(6)H(3))

Reduction of LAlI(2) (1) (L = HC[(CMe)(NAr)](2), Ar = 2,6-i-Pr(2)C(6)H(3)) with potassium in the presence of alkynes C(2)(SiMe(3))(2), C(2)Ph(2), and C(2)Ph(SiMe(3)) yielded the first neutral cyclopropene analogues of aluminum LAl[eta(2)-C(2)(SiMe(3))(2)] (3), LAl(eta(2)-C(2)Ph(2)) (4), and LAl[eta(2)-C(2)Ph(SiMe(3))] (5), respectively, whereas reduction of 1 in the presence of Ph(2)CO gave an aluminum pinacolate LAl[O(2)(CPh(2))(2)] (6), irrespective of the amount of Ph(2)CO employed. The unsaturated molecules CO(2), Ph(2)CO, and PhCN inserted into one of the Al-C bonds of 3 leading to ring enlargement to give novel aluminum five-membered heterocyclic systems LAl[OC(O)C(2)(SiMe(3))(2)] (7), LAl[OC(Ph)(2)C(2)(SiMe(3))(2)] (8), and LAl[NC(Ph)C(2)(SiMe(3))(2)] (9) in high yields. In contrast, 3 reacted with t-BuCN, 2,6-Trip(2)C(6)H(3)N(3) (Trip = 2,4,6-i-Pr(3)C(6)H(2)), and Ph(3)SiN(3) resulting in the displacement of the alkyne moiety to afford LAl[N(2)(Ct-Bu)(2)] (10) with an unprecedented aluminum-containing imidazole ring, and the first monomeric aluminum imides LAlNC(6)H(3)-2,6-Trip(2) (11) and LAlNSiPh(3) (12). All compounds have been characterized spectroscopically. The variable-temperature (1)H NMR studies of 3 and ESR measurements of 3 and 4 suggest that the Al-C-C three-membered-ring systems can be best described as metallacyclopropenes. The (27)Al NMR resonances of 2 and 3 are reported and compared. Molecular structures of compounds 3, 4, 6.OEt(2), 8.OEt(2), and 9 were determined by single-crystal X-ray structural analysis.     

Synthesis of carbaalane halogen derivatives

The carbaalane halogen derivatives [(AlX)(6)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(3))(6)] (X = F (9), Cl (7), Br (10), I (11)) were prepared in toluene from [(AlH)(6)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(3))(6)] (6) and BF(3).OEt(2), BX(3) (X = Br, I), Me(3)SnF, and Me(3)SiX (X = Cl, Br, I), respectively. A partially halogenated product [(AlH)(2)(AlX)(4)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(3))(6)] (12) (X = Cl (approximately 40%), Br (approximately 60%)) was obtained from 5 and impure BBr(3). [(AlH)(6)(AlNMe(3))(2)(CCH(2)Ph)(6)] (5) was converted to [(AlX)(6)(AlNMe(3))(2)(CCH(2)Ph)(6)] (X = F (13), Cl (14), Br (15), I (16)) using BF(3).OEt(2) and Me(3)SiX (X = Cl, Br, I), respectively. The X-ray single-crystal structures of 11.C(6)H(6), 12.3C(7)H(8), 13.6C(7)H(8), and 15.4C(7)H(8) were determined. Compounds 7 and 9-11 are soluble in benzene/toluene and could be well characterized by NMR spectroscopy and MS (EI) spectrometry. The results demonstrate the facile substitution of the hydridic hydrogen atoms in 5 and 6 by the halides with different reagents.     

Ruthenium tris(pyrazolyl)borate diazo complexes: preparation of aryldiazenido, aryldiazene, and hydrazine derivatives

Tris(pyrazolyl)borate aryldiazenido complexes [RuTpLL'(ArN(2))](BF(4))(2) (1-3) [Ar = C(6)H(5), 4-CH(3)C(6)H(4); Tp = hydridotris(pyrazolyl)borate; L = P(OEt)(3) or PPh(OEt)(2), L' = PPh(3); L = L' = P(OEt)(3)] were prepared by allowing dihydrogen [RuTp(eta(2)-H(2))LL'](+) derivatives to react with aryldiazonium cations. Spectroscopic characterization (IR, (15)N NMR) using the (15)N-labeled derivatives strongly supports the presence of a linear [Ru]-NN-Ar aryldiazenido group. Hydrazine complexes [RuTp(RNHNH(2))LL']BPh(4) (4-6) [R = H, CH(3), C(6)H(5), 4-NO(2)C(6)H(4); L = P(OEt)(3) or PPh(OEt)(2), L' = PPh(3); L = L' = P(OEt)(3)] were also prepared by reacting the [RuTp(eta(2)-H(2))LL'](+) cation with an excess of hydrazine. The complexes were characterized spectroscopically (IR and NMR) and by X-ray crystal structure determination of the [RuTp(CH(3)NHNH(2))[P(OEt)(3)](PPh(3))]BPh(4) (4d) derivative. Tris(pyrazolyl)borate aryldiazene complexes [RuTp(ArN=NH)LL']BPh(4) (7-9) (Ar = C(6)H(5), 4-CH(3)C(6)H(4)) were prepared following three different methods: (i). by allowing hydride species RuHTpLL' to react with aryldiazonium cations in CH(2)Cl(2); (ii). by treating aryldiazenido [RuTpLL'(ArN(2))](BF(4))(2) with LiBHEt(3) in CH(2)Cl(2); (iii). by oxidizing arylhydrazine [RuTp(ArNHNH(2))LL']BPh(4) complexes with Pb(OAc)(4) in CH(2)Cl(2) at -30 degrees C. Methyldiazene complexes [RuTp(CH(3)N=NH)LL']BPh(4) were also prepared by the oxidation of the corresponding methylhydrazine [RuTp(CH(3)NHNH(2))LL']BPh(4) with Pb(OAc)(4).     

Yttrium complexes incorporating the chelating diamides [ArN(CH2)xNAr]2- (Ar = C6H3-2,6-iPr2, x= 2, 3) and their unusual reaction with phenylsilane

Novel yttrium chelating diamide complexes [(Y[ArN(CH(2))(x)NAr](Z)(THF)(n))(y)] (Z = I, CH(SiMe(3))(2), CH(2)Ph, H, N(SiMe(3))(2), OC(6)H(3)-2,6-(t)Bu(2)-4-Me; x = 2, 3; n = 1 or 2; y = 1 or 2) were made via salt metathesis of the potassium diamides (x = 3 (3), x = 2 (4)) and yttrium triiodide in THF (5,10), followed by salt metathesis with the appropriate potassium salt (6-9, 11-13, 15) and further reaction with molecular hydrogen (14). 6 and 11(Z = CH(SiMe(3))(2), x = 2, 3) underwent unprecedented exchange of yttrium for silicon on reaction with phenylsilane to yield (Si[ArN(CH(2))(x)NAr]PhH) (x = 2 (16), 3) and (Si[CH(SiMe(3))(2)]PhH(2)).     

Biaryl formation in the synthesis of endo and exo-platinacycles

The reactions of cis-[Pt(2)(4-MeC(6)H(4))(4)(μ-SEt(2))(2)] with bifunctional ligands ArCH=NCH(2)(2-XC(6)H(4)) containing a C-X bond at the ortho positions of the benzyl ring (Ar = 4-ClC(6)H(4), X = Br (1d); Ar = 2,4,6-(CH(3))(3)C(6)H(2), X = Br (1e); Ar = 2,4,6-(CH(3))(3)C(6)H(2), X = Cl (1f); Ar = 2-CH(3)C(6)H(4), X = Br (1h); Ar = 2,6-F(2)C(6)H(3), X = Br (1i)) in refluxing toluene were studied. Several types of platinum(II) cyclometallated compounds containing a biaryl linkage were obtained: i) endo-five-membered with a Pt-C(sp(2)) bond (2d, 2h), ii) endo-six-membered with a Pt-C(sp(3)) bond (2e, 2f), and iii) exo-five membered with a Pt-C(sp(2)) bond (2i). The formed biaryl linkage involves the metallated ring for 2i and the non-metallated ring for the endo-metallacycles. The reaction of compounds 2 with PPh(3) produced the corresponding phosphine derivatives, some of which (3d, 3e, 3h and 3i) were characterised crystallographically. In addition, compound [PtBr{2-CH(3)C(6)H(3)C(6)H(4)CH=NCH(2)(2-C(6)H(4)Br)}SEt(2)] (2c) containing a seven-membered endo-metallacycle was also obtained and characterised crystallographically.     

Rare earth metal bis(amide) complexes bearing amidinate ancillary ligands: synthesis, characterization, and performance as catalyst precursors for cis-1,4 selective polymerization of isoprene

A family of rare earth metal bis(amide) complexes bearing monoanionic amidinate [RC(N-2,6-Me(2)C(6)H(3))(2)](-) (R = cyclohexyl (Cy), phenyl (Ph)) as ancillary ligands were synthesized and characterized. One-pot salt metathesis reaction of anhydrous LnCl(3) with one equivalent of amidinate lithium [RC(N-2,6-Me(2)C(6)H(3))(2)]Li, following the introduction of two equivalents of NaN(SiMe(3))(2) in THF at room temperature afforded the neutral and unsolvated mono(amidinate) rare earth metal bis(amide) complexes [RC(N-2,6-Me(2)C(6)H(3))(2)]Y[N(SiMe(3))(2)](2) (R = Cy (1); R = Ph (2)), and the "ate" mono(amidinate) rare earth metal bis(amide) complex [CyC(N-2,6-Me(2)C(6)H(3))(2)]Lu[N(SiMe(3))(2)](2)(μ-Cl)Li(THF)(3) (3) in 61-72% isolated yields. These complexes were characterized by elemental analysis, NMR spectroscopy, FT-IR spectroscopy, and X-ray single crystal diffraction. Single crystal structural determination revealed that the central metal in complexes 1 and 2 adopts a distorted tetrahedral geometry, and in complex 3 forms a distorted trigonal bipyramidal geometry. In the presence of AlMe(3), and in combination with one equimolar amount of [Ph(3)C][B(C(6)F(5))(4)], complexes 1 and 2 showed high activity towards isoprene polymerization to give high molecular weight polyisoprene (M(n) > 10(4)) with good cis-1,4 selectivity (>90%).     

β-Diketiminate Germylene-Supported Pentafluorophenylcopper(I) and -silver(I) Complexes [LGe(Me)(CuC(6)F(5))(n)](2) (n = 1, 2), LGe[C(SiMe(3))N(2)]AgC(6)F(5), and {LGe[C(SiMe(3))N(2)](AgC(6)F(5))(2)}(2) (L = HC[C(Me)N-2,6-iPr(2)C(6)H(3)](2)): Synthesis and Structural Characterization

Reactions of LGeMe (L = HC[C(Me)N-2,6-iPr(2)C(6)H(3)](2)) with 0.25 or 0.5 equiv of (CuC(6)F(5))(4) gave the products [LGe(Me)CuC(6)F(5)](2) (1) and [LGe(Me)(CuC(6)F(5))(2)](2) (2), respectively. In situ formed 1 reacted with 0.5 equiv of (CuC(6)F(5))(4) to give 2 on the basis of NMR ((1)H and (19)F) spectral measurements. Conversely, 2 was converted into 1 by treatment with 2 equiv of LGeMe. Reactions of LGeC(SiMe(3))N(2) with 1 or 2 equiv of AgC(6)F(5)·MeCN produced the corresponding compounds LGe[C(SiMe(3))N(2)]AgC(6)F(5) (3) and {LGe[C(SiMe(3))N(2)](AgC(6)F(5))(2)}(2) (4). Similarly, 3 was converted into 4 by treatment with 1 equiv of AgC(6)F(5)·MeCN and 4 converted into 3 by reaction with 2 equiv of LGeC(SiMe(3))N(2). X-ray crystallographic studies showed that 1 contains a rhombically bridged (CuC(6)F(5))(2), while 2 has a chain-structurally aggregated (CuC(6)F(5))(4), both supported by LGeMe. Correspondingly, 3 showed a terminally bound AgC(6)F(5) and 4 a chain-structurally aggregated (AgC(6)F(5))(4), both supported by LGeC(SiMe(3))N(2). Photophysical studies proved that the Ge-Cu metal-metalloid donor-acceptor bonding persists in solutions of 1 and 2 and Ge-Ag donor-acceptor bonding in solutions of 3 and 4 as a result of the clear migration of their emission bands compared to those of the corresponding starting materials. Low-temperature (-50 °C) (19)F NMR spectral measurements detected dissociation of 1, 2, and 4 by the aggregation part of the CuC(6)F(5) or AgC(6)F(5) entities in solution. These results provide good support for pentafluorophenylcopper(I) or -silver(I) species having β-diketiminate germylene as a donor because of its remarkably electronic and steric character.     

Syntheses, structures and reactions of a series of beta-diketiminatoyttrium compounds

This paper describes the synthesis and selected reactions of a series of crystalline mono(beta-diiminato)yttrium chlorides , , , , , , and . The X-ray structure of each has been determined, as well as of [YCl()(2)] (), [Y()(2)OBu(t)] () and [Y{CH(SiMe(3))(2)}(thf)(mu-Cl)(2)Li(OEt(2))(2)(mu-Cl)](2) (). The N,N'-kappa(2)-beta-diiminato ligands were [{N(R)C(Me)}(2)CH](-) [R = C(6)H(4)Pr(i)-2 (); R = C(6)H(4)Bu(t)-2 (); R = C(6)H(3)Pr(i)(2)-2,6 ()], [{N(SiMe(3))C(Ph)}(2)CH)](-) () and [{N(C(6)H(3)Pr(i)(2)-2,6)C(H)}(2)CPh](-) (). Equivalent portions of Li[L(x)] and YCl(3) in Et(2)O under mild conditions yielded [Y(mu-Cl)(L(x))(mu-Cl)(2)Li(OEt(2))(2)](2) [L(x) = () or ()] and [Y(mu-Cl)()(mu-Cl)Li(OEt(2))(2)(mu-Cl)](2) () or its thf (instead of Et(2)O) equivalent . Each of the Li(OEt(2))(2)Cl(2) moieties is bonded in a terminal () or bridging () mode with respect to the two Y atoms; the difference is attributed to the greater steric demand of than or . Under slightly more forcing conditions, YCl(3) and Li() (via) gave the lithium-free complex [YCl(2)()(thf)(2)] (). Two isoleptic compounds and (having in place of in , and , respectively) were obtained from YCl(3) and an equivalent portion of K[] and Na[], respectively; under the same conditions using Na[], the unexpected product was [YCl()(2)] () (i.e. incorporating only one half of the YCl(3)). A further unusual outcome was in the formation of from and 2 Li[CH(SiMe(3))(2)]. Compound [Y(){N(H)C(6)H(3)Pr(i)(2)-2,6}(thf)(mu(3)-Cl)(2)K](2).4Et(2)O (), obtained from and K[N(H)C(6)H(3)Pr(i)(2)-2,6], is noteworthy among group 3 or lanthanide metal (M) compounds for containing MClKCl (M = Y) moieties.     

Synthesis and structures of crystalline Li, Al and Sn(II) 1-azaallyls and beta-diketiminates derived from [Li{mu,eta3-N(SiMe3)C(Ad)C(H)SiMe3}]2 (Ad = 1-adamantyl)

The crystalline dimeric 1-azaallyllithium complex [Li{mu,eta(3-N(SiMe3)C(Ad)C(H)SiMe3}]2 (1) was prepared from equivalent portions of Li[CH(SiMe3)2] and 1-cyanoadamantane (AdCN). Complex was used as precursor to each of the crystalline complexes 2-8 which were obtained in good yield. By 1-azaallyl ligand transfer, 1 afforded (i) [Al{eta3-N(SiMe3)C(Ad)C(H)SiMe3}{kappa1-N(SiMe3)C(Ad)=C(H)SiMe3-E}Me] (5) with [AlCl2Me](2), (ii) [Sn{eta3-N(SiMe3)C(Ad)C(H)SiMe3}2] (7) with Sn[N(SiMe3)2]2, and (iii) [Li(N{C(Ad)=C(H)SiMe3-E}{Si(NN)SiMe3})(thf)2] (8) with the silylene Si[(NCH(2)Bu(t))2C6H(4)-1,2] [= Si(NN)]. By insertion into the C[triple bond, length as m-dash]N bond of the appropriate cyanoarene RCN, gave the beta-diketiminate [Li{mu-N(SiMe3)C(Ad)C(H)C(R)NSiMe3}]2 [R = Ph (2), C(6)H(4)Me-4 (3)], and yielded [Al{kappa2-N(SiMe3)C(Ad)C(H)C(Ph)NSiMe3}{kappa1-N(SiMe3)C(Ad)=C(H)SiMe3-E}Me] (6). The beta-diketiminate [Al{kappa2-N(SiMe3)C(Ad)C(H)C(Ph)NSiMe3}Me2] (4) was prepared from 2 and [AlClMe2]2. The X-ray structures of 1 and 3-8 are presented. Multinuclear NMR spectra in C6D6 or C6D5CD3 have been recorded for each of 1-8; such data on 8 revealed that in solution two minor isomers were also present.     

Synthesis and structures of the first cationic perfluoroaryllanthanoid(II) complexes

Tetraphenylborate salts of solvated pentafluorophenyllanthanoid(II) cations [Ln(C(6)F(5))(thf)(n)](+) (Ln=Eu, n=6 (1); Ln=Yb, n=5 (2)) were readily synthesized in high yield by reactions of ytterbium or europium with HgPh(C(6)F(5)) and Me(3)NHBPh(4) in THF. The structures of 1.THF and 2 confirmed the existence of well-separated ions and both 1 and 2 show notable thermal stability at room temperature. The cation in 2 was also observed in the remarkable mixed-valent complex [Yb(II)(C(6)F(5))(thf)(5)][Yb(III)(C(6)F(5))(2)[N(SiMe(3))(2)](2)] (3), fortuitously isolated in low yield from a reaction of ytterbium metal, HgPh(C(6)F(5)), and HN(SiMe(3))(2) in THF, and which additionally has an unusual bis(pentafluorophenyl)bis[bis(trimethylsilyl)amido)]ytterbate(III) anion. (171)Yb-(19)F coupling has been observed in the low-temperature (171)Yb NMR spectra of 2 and [Yb(C(6)F(5))(2)(thf)(4)].     

Enantiomerically pure phosphaalkene-oxazolines (PhAk-Ox): synthesis, scope and copolymerization with styrene

The design of a synthetic route to a class of enantiomerically pure phosphaalkene-oxazolines (PhAk-Ox) is presented. The condensation of a lithium silylphosphide and a ketone (the phospha-Peterson reaction) was used as the P=C bond-forming step. Attempted condensation of PhC(=O)Ox (Ox = CNOCH(iPr)CH(2)) and MesP(SiMe(3))Li gave the unusual heterocycle (MesP)(2)C(Ph)=CN-(S)-CH(iPr)CH(2)O (3). However, PhAk-Ox (S,E)-MesP=C(Ph)CMe(2)Ox (1?a) was successfully prepared by treating MesP(SiMe(3))Li with PhC(=O)CMe(2)Ox (52?%). To demonstrate the modularity and tunability of the phospha-Peterson synthesis several other phosphaalkene-oxazolines were prepared in an analogous manner to 1?a: TripP=C(Ph)CMe(2)Ox (1?b; Trip = 2,4,6-triisopropylphenyl), 2-iPrC(6)H(4)P=C(Ph)CMe(2)Ox (1?c), 2-tBuC(6)H(4)P=C(Ph)CMe(2)Ox (1?d), MesP=C(4-MeOC(6)H(4))CMe(2)Ox (1?e), MesP=C(Ph)C(CH(2))(4)Ox (1?f), and MesP=C(3,5-(CF(3))(2)C(6)H(3))C(CH(2))(4)Ox (1?g). To evaluate the PhAk-Ox compounds as prospective precursors to chiral phosphine polymers, monomer 1?a and styrene were subjected to radical-initiated copolymerization conditions to afford [{MesPC(Ph)(CMe(2)Ox)}(x){CH(2)CHPh}(y)](n) (9?a: x = 0.13n, y = 0.87n; GPC: M(w) = 7400?g mol(-1) , PDI = 1.15).     

1H,1H,2H,2H-perfluoroalkyl-functionalization of Ni(II), Pd(II), and Pt(II) mono- and diphosphine complexes: minimizing the electronic consequences for the metal center

A series of fluorous derivatives of group 10 complexes MCl(2)(dppe) and [M(dppe)(2)](BF(4))(2) (M = Ni, Pd or Pt; dppe = 1,2-bis(diphenylphosphino)ethane) and cis-PtCl(2)(PPh(3))(2) was synthesized. The influence of para-(1H,1H,2H,2H-perfluoroalkyl)dimethylsilyl-functionalization of the phosphine phenyl groups of these complexes, as studied by NMR spectroscopy, cyclovoltammetry (CV), XPS analyses, as well as DFT calculations, points to a weak steric and no significant inductive electronic effect. The steric effect is most pronounced for M = Ni and leads in the case of NiCl(2)(1c) (3c) and [Ni(1c)(2)](BF(4))(2) (7c) (1c = [CH(2)P[C(6)H(4)(SiMe(2)CH(2)CH(2)C(6)F(13))-4](2)](2)) to a tetrahedral distortion from the expected square planar geometry. The solubility behavior of NiCl(2)[CH(2)P[C(6)H(4)(SiMe(3-b)(CH(2)CH(2)C(x)F(2x+1)b)-4](2)](2) (3: b = 1-3; x = 6, 8) in THF, toluene, and c-C(6)F(11)CF(3) was found to follow the same trends as those observed for the free fluorous ligands 1. A similar correlation between the partition coefficient (P) of complexes 3 and free 1 was observed in fluorous biphasic solvent systems, with a maximum value obtained for 3f (b = 3, x = 6, P = 23 in favor of the fluorous phase).     

A convenient synthesis of new isolable phosphaalkenes using the base-induced rearrangement of secondary vinylphosphines

The secondary vinylphosphines Ar(F)P(H)C(R)[double bond]CH(2) [2a, Ar(F) = 2,6-(CF(3))(2)C(6)H(3), R = CH(3); 2b, Ar(F) = 2,6-(CF(3))(2)C(6)H(3), R = C(6)H(5); 2c, Ar(F) = 2,4,6-(CF(3))(3)C(6)H(2), R = CH(3)] were prepared by treating the corresponding dichlorophosphine Ar(F)PCl(2) (1) with H(2)C[double bond]C(R)MgBr. In the presence of catalytic base (DBU or DABCO) the vinylphosphines (2a-c) undergo quantitative 1,3-hydrogen migration over 3 d to give stable and isolable phosphaalkenes Ar(F)P=C(R)CH(3) (3a, Ar(F) = 2,6-(CF(3))(2)C(6)H(3), R = CH(3); 3b, Ar(F) = 2,6-(CF(3))(2)C(6)H(3), R = C(6)H(5); 3c, Ar(F) = 2,4,6-(CF(3))(3)C(6)H(2), R = CH(3)). Under analogous conditions, only 90% conversion is observed in the base-catalyzed rearrangement of MesP(H)C(CH(3))[double bond]CH(2) to MesP[double bond]C(CH(3))(2). Presumably, the increase in acidity of the P-H group when electron-withdrawing groups are employed (i.e. 2a-c) favors quantitative rearrangement to the phosphaalkene tautomer (3a-c). Thus, the double-bond migration reaction is a convenient and practical method of preparing new phosphaalkenes with C-methyl substituents.     

Synthetic and structural experiments on yttrium, cerium and magnesium trimethylsilylmethyls and their reaction products with nitriles; with a note on two cerium beta-diketiminates

The yttrium, cerium and magnesium bis(trimethylsilyl)methyls [Ln[CH(SiMe3)2]3][Ln = Y (1), Ce (2)], and the known compound Mg[[CH(SiMe3)2]2 (C) and [Mg(mu-Br)[CH(SiMe3)2](OEt2)]2 (D) formed the crystalline nitrile adducts [1(NCBut)2] (5), [2(NCPh)] (6), [C(NCR)2][R = But (8), Ph (9), C6H3Me2-2,6 (10)] and [Mg(mu-Br)[CH(SiMe3)2](NCR)]2 [R = But (11), Ph (12), C6H3Me2-2,6 (13)], rather than beta-diketiminato-metal insertion products. The beta-diketiminato-cerium complex [Ce[(N(SiMe3)C(C6H4But-4))2CH][N(SiMe3)2]2] (16) was obtained from [Ce[N(SiMe3)2]3] and the beta-diketimine H[[N(SiMe3)C(C6H4But-4)]2CH]]. The cerium alkyl 2 and [Ln[CH(SiMe3)(SiMe2OMe)]3][Ln = Y (3), Ce (4)] were obtained from the appropriate lithium alkyl precursor and [Ce(OC6H2But2-2,6-Me-4)3] or LnCl3, respectively. Heating complex 3 with benzonitrile in toluene afforded 2,2-dimethyl-4,6-diphenyl-5-trimethylsilyl-1,3-diaza-2-silahexa-1,3-diene (7), a member of a new class of heterocycles. The X-ray structures of the crystalline compounds, D, [Mg[CH(SiMe3)2]2(OEt2)2], the known [Ce(Cl)[(N(SiMe3)C(Ph))2CH]2] (E) and 16 are reported. The cerium alkyl (like 1) has one close Ce...C contact for each ligand, attributed to a gamma-C-Ce agostic interaction. The Ln alkyls and have a trigonal prismatic arrangement of the chelating ligands (each of the same chirality at Calpha) around the metal. In an arene solution at 313 K exists as two isomers, as evident from detailed NMR spectroscopic experiments.