Presence Of NaBPh4 Research Articles

Complex Featuring Two Double Dative Bonds Between Carbon(0) and Uranium

Complex Featuring Two Double Dative Bonds Between Carbon(0) and Uranium

Polymerization of Alkyl Diazoacetates Initiated by Pd(Naphthoquinone)/Borate Systems: Dual Role of Naphthoquinones as Oxidant and Anionic Ligand for Generating Active Pd(II) Species

For polymerization of alkyl diazoacetates, the combination of a Pd complex bearing 1,4-naphthoquinone (NQ) or its derivatives as a ligand and borate, NaBPh4, was found to be an efficient initiating system. The polymerization of ethyl diazoacetate by a Pd(0) complex having two NQ molecules [Pd(nq)2] with NaBPh4 proceeded to give poly(ethoxycarbonylmethylene)s with a relatively high molecular weight (up to Mn = 36 kDa) in good yield (∼70%). This initiating system was also effective for polymerizing other diazoacetates, benzyl and cyclohexyl diazoacetates. In addition, in the presence of NaBPh4, a novel Pd(II) complex bearing an anionic naphthoquinonyl ligand derived from 2,3-dichloro-1,4-naphthoquinone (dichlone), [Pd(cod)(Cl-nq)Cl] (cod = 1,5-cyclooctadiene), which was newly prepared by treatment of a Pd(0) precursor, Pd2(dba)3·CHCl3 [dba = (E,E)-dibenzylideneacetone], with COD and dichlone, was capable of affording poly(alkoxycarbonylmethylene)s with much higher stereoregularity compared to the previously...

Crystal structure of cis-1-phenyl-8-(pyridin-2-ylmeth-yl)dibenzo[1,2-c:2,1-h]-2,14-dioxa-8-aza-1-borabi-cyclo-[4.4.0]deca-3,8-diene.

The title compound, C26H23BN2O2, was obtained as by product during synthetic attempts of a complexation reaction between the tripodal ligand H2L [N,N-bis-(2-hy-droxy-benz-yl)(pyridin-2-yl)methyl-amine] and manganese(III) acetate in the presence of NaBPh4. The isolated B-phenyl dioxaza-borocine contains an N→B dative bond with a cis conformation. In the crystal, C-H⋯O hydrogen bonds define chains parallel to the b-axis direction. A comparative analysis with other structurally related derivatives is also included, together with a rationalization of the unexpected production of this zwitterionic heterocycle.

Precise synthesis of thermoreversible block copolymers containing reactive furfuryl groups via living anionic polymerization: the countercation effect on block copolymerization behavior

Well-defined block copolymers containing furan groups were anionically synthesized in the presence of NaBPh4 and used for the formation of thermoreversible networks via a Diels–Alder click reaction.

Membrane formation by preferential solvation of ions in mixture of water, 3-methylpyridine, and sodium tetraphenylborate

The structure and dynamics of a ternary system composed of deuterium oxide (D2O), 3-methylpyridine (3MP), and sodium tetraphenylborate (NaBPh4) are investigated by means of small-angle neutron scattering (SANS) and neutron spin echo (NSE) techniques. In the SANS experiments, a structural phase transition is confirmed between a disordered-phase and an ordered-lamellar-phase upon variation of the composition and/or temperature of the mixture. The characteristic lengths of the structures is on the sub-micrometer scale. A dispersion relation of the structure is measured through NSE experiments, which shows that the relaxation rate follows a cubic relation with momentum transfer. This implies that the dynamics of the system are determined predominantly by membrane fluctuations. The present results indicate that 3MP-rich domains are microscopically separated from bulk water in the presence of NaBPh4, and that the layers behave as membranes. These results are interpreted that preferential solvation of salt in each solvent induces a microphase separation between the solvents, and the periodic structure of 3MP-rich domains is stabilized by the long-range electrostatic interaction arising from Na(+) ions in D2O-rich domains.

Synthesis and Characterization of (smif)2Mn(n= 0, M = V, Cr, Mn, Fe, Co, Ni, Ru;n= +1, M = Cr, Mn, Co, Rh, Ir; smif =1,3-di-(2-pyridyl)-2-azaallyl)

A series of Werner complexes featuring the tridentate ligand smif, that is, 1,3-di-(2-pyridyl)-2-azaallyl, have been prepared. Syntheses of (smif)(2)M (1-M; M = Cr, Fe) were accomplished via treatment of M(NSiMe(3))(2)(THF)(n) (M = Cr, n = 2; Fe, n = 1) with 2 equiv of (smif)H (1,3-di-(2-pyridyl)-2-azapropene); ortho-methylated ((o)Mesmif)(2)Fe (2-Fe) and ((o)Me(2)smif)(2)Fe (3-Fe) were similarly prepared. Metatheses of MX(2) variants with 2 equiv of Li(smif) or Na(smif) generated 1-M (M = Cr, Mn, Fe, Co, Ni, Zn, Ru). Metathesis of VCl(3)(THF)(3) with 2 Li(smif) with a reducing equiv of Na/Hg present afforded 1-V, while 2 Na(smif) and IrCl(3)(THF)(3) in the presence of NaBPh(4) gave [(smif)(2)Ir]BPh(4) (1(+)-Ir). Electrochemical experiments led to the oxidation of 1-M (M = Cr, Mn, Co) by AgOTf to produce [(smif)(2)M]OTf (1(+)-M), and treatment of Rh(2)(O(2)CCF(3))(4) with 4 equiv Na(smif) and 2 AgOTf gave 1(+)-Rh. Characterizations by NMR, EPR, and UV-vis spectroscopies, SQUID magnetometry, X-ray crystallography, and DFT calculations are presented. Intraligand (IL) transitions derived from promotion of electrons from the unique CNC(nb) (nonbonding) orbitals of the smif backbone to ligand π*-type orbitals are intense (ε ≈ 10,000-60,000 M(-1)cm(-1)), dominate the UV-visible spectra, and give crystals a metallic-looking appearance. High energy K-edge spectroscopy was used to show that the smif in 1-Cr is redox noninnocent, and its electron configuration is best described as (smif(-))(smif(2-))Cr(III); an unusual S = 1 EPR spectrum (X-band) was obtained for 1-Cr.

Preparation and reactivity of half-sandwich hydrazine complexes of ruthenium and osmium

Hydrazine complexes [MCl(η 6- p-cymene)(RNHNH 2)L]BPh 4 ( 1– 6) [M = Ru, Os; R = H, Me, Ph; L = P(OEt) 3, PPh(OEt) 2, PPh 2OEt] were prepared by allowing dichloro complexes MCl 2(η 6- p-cymene)L to react with hydrazines RNHNH 2 in the presence of NaBPh 4. Treatment of ruthenium complexes [RuCl(η 6- p-cymene)(RNHNH 2)L]BPh 4 with Pb(OAc) 4 led to acetate complex [Ru(κ 2–O 2CCH 3)(η 6- p-cymene)L]BPh 4 ( 7). Instead, the reaction of osmium derivatives [OsCl(η 6- p-cymene)(CH 3NHNH 2)L]BPh 4 with Pb(OAc) 4 afforded the methyldiazenido complex [Os(CH 3N 2)(η 6- p-cymene)L}]BPh 4 ( 8). Treatment with HCl of this diazenido complex 8 led to the methyldiazene cation [OsCl(CH 3N NH)(η 6- p-cymene)L}] + ( 9 +). The complexes were characterised spectroscopically and by X-ray crystal structure determination of [OsCl(η 6- p-cymene)(PhNHNH 2){PPh(OEt) 2}]BPh 4 ( 6b) and [Ru(κ 2–O 2CCH 3)(η 6- p-cymene){PPh(OEt) 2}]BPh 4 ( 7b).

Preparation of Pyrazole–Pyrazolate Half‐Sandwich Complexes of Ruthenium and Osmium

AbstractPyrazole (HRpz) [MCl(η6‐p‐cymene)(HRpz)L]BPh4 (1–8) and imidazole (HIm) complexes [MCl(η6‐p‐cymene)(HIm)L]BPh4 (9–10) [M = Ru, Os; R = H, 3‐Me, 3,5‐Me2; L = P(OEt)3, PPh(OEt)2, PPh2OEt, CNtBu] were prepared by allowing the dichloro compounds MCl2(η6‐p‐cymene)L to react with the appropriate azole in the presence of NaBPh4. Treatment of the dichloro complexes with an excess of both pyrazole and NEt3 yielded the pyrazole–pyrazolate derivatives [M(Rpz)(η6‐p‐cymene)(HRpz)L]BPh4 (11–14). Conversely, the reaction of carbonyl compounds RuCl2(η6‐p‐cymene)(CO) with pyrazole or imidazole yielded the bisazole complexes [MCl(η6‐p‐cymene)(HRpz)2]BPh4 or [MCl(η6‐p‐cymene)(HIm)2]BPh4 (15–17). The complexes were characterised spectroscopically (IR and 1H, 13C, 31P NMR) and by X‐ray crystal structure analysis [RuCl(η6‐p‐cymene)(HRpz){PPh(OEt)2}]BPh4 (1b), [Ru(pz)(η6‐p‐cymene)(HRpz){P(OEt)3}]BPh4 (11a) and [RuCl(η6‐p‐cymene)(HRpz)2]BPh4 (15).

Activation and transformation of white phosphorus by palladium(ii) complexes

A reaction of bis(triphenylphosphine)palladium dibromide with white phosphorus in the presence of NaBPh4 selectively gives phosphorous acid H3PO3. The mechanism of the formation involves coordination of a white phosphorus molecule, ligand exchange, and hydrolysis of the coordinated P4 molecule in the coordination sphere of palladium.

Preparation of imine complexes of ruthenium and osmium stabilised by [MCl(η 6-p-cymene)(PR3)]+ fragments

Imine complexes [MCl(η 6 -p- cymene){η 1 -NH C(H)Ar}(PR 3 )]BPh 4 ( 1 – 3 ) [M = Ru, Os; PR 3 = PPh(OEt) 2 , PPh 2 OEt; Ar = Ph, p- tolyl] were prepared by reacting MCl 2 (η 6 -p- cymene)(PR 3 ) precursors with benzyl azide ArCH 2 N 3 in the presence of NaBPh 4 . Benzophenone-imine complexes [MCl(η 6 -p- cymene){η 1 -NH CPh 2 }(PR 3 )]BPh 4 ( 4 – 6 ) [M = Ru, Os; PR 3 = PPh(OEt) 2 , PPh 2 OEt] were also prepared by allowing MCl 2 (η 6 -p- cymene)(PR 3 ) to react with Ph 2 C NH in the presence of NaBPh 4 . The complexes were characterised spectroscopically (IR, 1 H, 13 C, 31 P, 15 N NMR) and by X-ray crystal structure determination of [RuCl(η 6 -p- cymene){η 1 -NH C(H) -p- tolyl}{PPh(OEt) 2 }]BPh 4 ( 1b ).

Synthesis and structure of indenylnickel(II) chlorides bearing free N-heterocyclic carbene ligands and their catalysis for styrene polymerization

The reaction of (R-Ind) 2Ni (Ind = C 9H 7, indenyl) with an equivalent of a bulky aryl-substituted imidazolium salt in CH 2Cl 2/THF at 45 °C results in the corresponding N-heterocyclic carbene (NHC) indenylnickel(II) chloride of the type (R-Ind)Ni(L)Cl [R = 1-H, L = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr), 1; R = 1-Me, L = IPr, 2] in high yield. Complexes 1 and 2 were characterized by elemental analysis, NMR spectroscopy and X-ray crystallography. The resulted NHC indenylnickel(II) complexes are capable of polymerizing styrene in the presence of NaBPh 4 to give atactic polystyrene with M n values in the range of 10 4. The present studies show a close relationship between the structure and catalytic activity of the NHC indenylnickel(II) halides (including the previously reported indenylnickel(II) halides bearing alkyl-substituted NHC ligands), and complex 2 shows the highest catalytic activity. In comparison with its phosphine analogue (1-Me-Ind)Ni(PPh 3)Cl, complex 2 shows significant improvements in stability and catalytic performance.

Unexpected isolation and structural characterization of a redox-active Fe(II) piano-stool complex with an η 1-dppe ligand

A new cationic complex [(η 2-bipy)(η 5-C 5Me 5)Fe(η 1-dppe)][BPh 4] featuring a pendant free diphenylphosphine arm has been isolated in good yield after reaction of 2,2′-bipyridine with the known chloro precursor complex (η 2-dppe)(η 5-C 5Me 5)FeCl in presence of NaBPh 4. This complex which can be envisioned as a new redox-active building-block has been structurally characterized.

Exploring the coordination chemistry and reactivity of hemilabile N-alkylaminopyrazole ligands towards Pd(II)

Reaction of the N-alkylaminopyrazole ( NN′ N) ligands bis[(3,5-dimethyl-1-pyrazolyl)methyl]ethylamine ( bdmae) and bis[(3,5-dimethyl-1-pyrazolyl)methyl]isopropylamine ( bdmai) with [PdCl 2(CH 3CN) 2] in a 1:1 M/L ratio in CH 2Cl 2 produces cis-[PdCl 2( NN′ N)] ( NN′ N = bdmae ( 1), bdmai ( 2)). The solid state structure of complex 1 was determined by X-ray diffraction studies. The bdmae ligand is coordinated through the two N pz atoms to the metal atom, which completes its coordination with two chlorine atoms in a cis disposition. Treatment of the corresponding ligand with [PdCl 2(CH 3CN) 2] in 1:1 M/L ratio in the presence of AgBF 4 and metathesis with NaBPh 4 in CH 2Cl 2/CH 3OH (3:1) gave [PdCl( bdmae)](BPh 4) ( 3), and in the presence of NaBPh 4 in CH 2Cl 2/CH 3CN (3:1) gave [PdCl( bdmai)](BPh 4) ( 4). Complexes 1 and 2 were again obtained when complexes 3 and 4 were heated under reflux in a solution of Et 4NCl in acetonitrile. These Pd(II) compounds were characterised by elemental analyses, conductivity measurements, IR, 1H and 13C{ 1H} NMR, HMQC and NOESY spectroscopies. The NMR studies of the complexes prove the rigid conformation of the ligands when they are complexed.

Unprecedented formation of selenido-bridged tri-nuclear palladium(II) and platinum(II) complexes, [M 3(μ 3-Se) 2(P ∩P) 3] 2+, via C–Se bond cleavage

Reaction of [M(SeCOC 6H 4Me-4) 2(P ∩P)] with MCl 2(P ∩P) in the presence of NaBPh 4 in dichloromethane–methanol mixture afforded selenido-bridged tri-nuclear complexes [M 3(μ 3-Se) 2(P ∩P) 3][BPh 4] 2 (M 3 = Pd 3, Pt 3, Pd 2Pt, PdPt 2; P ∩P = dppm, dppe, dppp, (P n Pr 3) 2) formed via unprecedented cleavage of C–Se linkage of selenocarboxylate. These complexes were characterized by UV–Vis and NMR ( 1H, 31P, 77Se, 195Pt) spectroscopy. The structure of [Pd 3(μ 3-Se) 2(dppe) 3][BPh 4] 2 was established by X-ray crystallography. The geometry around each palladium atom is approximately square planar with two P atoms from the chelating dppe and two Se atoms defining the coordination sphere.

Indenylnickel(II) Halides for the Polymerization of Styrene in the Presence of NaBPh4/PPh3

The catalytic activity of a series of indenylnickel(II) halides: (1-R-Ind)Ni(PPh3)X (R=ethyl, cyclopentyl and benzyl, while X=Cl, Br and I), towards styrene polymerization was studied in the presence of NaBPh4 and PPh3. The catalytic property of these halides was related to the substituent group on the indenyl ligand and the halogen atom bonded to the metal atom. Among them, the (1-Et-Ind)Ni(PPh3)Cl/NaBPh4/PPh3 system showed the highest activity for the polymerization of styrene, and the polystyrene obtained was a syndio-rich (rr triad) atactic polymer with Mn values in the range of 103–104. The mechanism of the styrene polymerization initiated by the (1-Et-Ind)Ni(PPh3)Cl/NaBPh4/PPh3 system was studied.

Synthesis of Salicylaldiminato-Functionalized N-Heterocyclic Carbene Complex of Nickel(II) and Its Catalytic Activity for Styrene Polymerization

A novel potentially tridentate N-heterocyclic carbene (NHC) precursor, anionic salicylaldimine-functionalized imidazolium bromide, [3,5-tBu2-2-(HO)C6H2CHNCH2CH2(CH{NCHCHNiPr})Br] (HL·HBr, 2), was designed. The reaction of in situ-generated monoanionic tridentate salicylaldiminato-functionalized NHC LNa with Ni(PPh3)2Br2 affords a novel mono-ligand Ni(II) bromide, [3,5-tBu2-2-(O)C6H2CHNCH2CH2(C{NCHCHNiPr})]NiBr (LNiBr, 3), in good yield. Complex 3 can also be synthesized by the direct reaction of nickelocene (Cp)2Ni or bis-indenyl Ni(II) complex (Ind)2Ni with 2 in high yield via the cyclopentadiene or indene elimination reaction, respectively. Complex 3 has been fully characterized including X-ray structural determination. Preliminary study indicated that 3 shows good catalytic activity for the polymerization of styrene in the presence of NaBPh4 at 80 °C.

Palladium(II) and platinum(II) monoselenocarboxylates: Synthesis, spectroscopy, structure and their use as molecular precursors for metal selenides

Treatment of MCl 2(P ∩P) or MCl 2(P n Pr 3) 2 with two equivalents of ArCOSeK readily yields cis-[M(SeCOAr) 2(P ∩P)] and trans-[M(SeCOAr) 2(P n Pr 3) 2], respectively (M = Pd or Pt; Ar = Ph or 4-MeC 6H 4; P ∩P = dppm, dppe, dppp). The reaction of Pd(SeCOAr) 2(dppe) with PdCl 2(dppe) in the presence of NaBPh 4 in methanol gave a tri-nuclear ionic complex, [Pd 3(μ 3-Se) 2(dppe) 3][BPh 4] 2. These complexes were characterized by UV–Vis, IR and NMR spectroscopy. The complex [Pt(SeCOPh) 2(dppp)] has been structurally characterized by X-ray crystallography. The coordination environment around square planar platinum atom is defined by chelating dppp ligand and two unidentate selenocarboxylates bonded through selenium atoms. Pyrolysis of [Pd(SeCOAr) 2(P n Pr 3) 2] either in tri- n-butylphosphate (TBP) (at 200 °C) or in the solid state (furnace heating at 350 °C) gave Pd 17Se 15.

Substituents Effects in POP Pincer Complexes of Ruthenium

Reactions of [RuCl2(p-cymene)]2 with (tBu2PCH2CH2)2O (POP-tBu) and (iPr2PCH2CH2)2O (POP-iPr) afforded RuCl2(POP-tBu) (1) and [Ru2(μ-Cl)3(POP-iPr)2]Cl (2·Cl), respectively. The POP ligand is coordinated in a mer fashion in complex 1, whose crystal structure revealed a γ-agostic C−H···Ru interaction of one tBu group. Spectroscopic evidence indicated that this agostic interaction is retained in 1 in solution. A related compound, [Ru(N2)Cl(POP-tBu)]BPh4 (4), which also showed agostic bonding of a tBu group, was obtained by substitution of N2 for Cl- in 1, in the presence of NaBPh4. Compound 2·Cl readily underwent ion exchange with LiBPh4 or LiPF6 to give 2·BPh4 or 2·PF6 salts, respectively. A crystallographic analysis of 2·PF6 established a co-facial bioctahedral geometry of the [Ru2(μ-Cl)3(POP-iPr)2]+ cation containing two POP ligands coordinated in a fac fashion. Reactions of 1 and 2 with H2 afforded the dihydrogen complexes cis,trans-Ru(H2)Cl2(POP-tBu) (3) and cis,cis-Ru(H2)Cl2(POP-iPr) (5), respectively. The H−H bond distances are very similar in both compounds, r(H−H) = 1.0 ± 0.1 Å, based on the T1min and JHD data and results of DFT calculations. Reaction of 2 with N2 gave the dinitrogen complex cis,cis-Ru(N2)Cl2(POP-iPr) (6), but solutions of 1 under a nitrogen atmosphere showed no evidence of an analogous compound. The different steric requirements of the phosphorus substituents of the POP ligands were identified as the source of the differences in the coordination properties of the POP-tBu and POP-iPr complexes 1−6.

Cationic methyl complexes of rhodium(III): synthesis, structure, and some reactions

Cationic methyl complex of rhodium(III), trans-[Rh(Acac)(PPh 3) 2(CH 3)(CH 3CN)][BPh 4] ( 1) is prepared by interaction of trans-[Rh(Acac)(PPh 3) 2(CH 3)I] with AgBPh 4 in acetonitrile. Cationic methyl complexes of rhodium(III), cis-[Rh(Acac)(PPh 3) 2 (CH 3)(CH 3CN)][BPh 4] ( 2) and cis-[Rh(BA)(PPh 3) 2(CH 3)(CH 3CN)][BPh 4] ( 3) (Acac, BA are acetylacetonate and benzoylacetonate, respectively), are obtained by CH 3I oxidative addition to rhodium(I) complexes [Rh(Acac)(PPh 3) 2] and [Rh(BA)(PPh 3) 2] in acetonitrile in the presence of NaBPh 4. Complexes 2 and 3 react readily with NH 3 at room temperature to form cis-[Rh(Acac)(PPh 3) 2(CH 3)(NH 3)][BPh 4] ( 4) and cis-[Rh(BA)(PPh 3) 2(CH 3)(NH 3)][BPh 4] ( 5), respectively. Complexes 1– 5 were characterized by elemental analysis, 1H and 31P{ 1H} NMR spectra. Complexes 1, 2, 3 and 4 were characterized by X-ray diffraction analysis. Complexes 2 and 3 in solutions (CH 2Cl 2, CHCl 3) are presented as mixtures of cis-(PPh 3) 2 isomers involved into a fluxional process. Complex 2 on heating in acetonitrile is converted into trans-isomer 1. In parallel with that isomerization, reductive elimination of methyl group with formation of [CH 3PPh 3][BPh 4] takes place. Replacement of CH 3CN in complexes 1 and 2 by anion I − yields in both cases the neutral complex trans-[Rh(Acac)(PPh 3) 2(CH 3)I]. Strong trans influence of CH 3 ligand manifests itself in the elongation (in solid) and labilization (in solution) of rhodium–acetonitrile nitrogen bond.

Complex formation of 2,2-diphenyl-2H-benzo[f]chromene containing the aza-18-crown-6-ether fragment in the polymeric layer

The synthesis of 2,2-diphenyl-2H-benzo[f]chromene containing the aza-18-crown-6-ether fragment was described. Its complex formation with alkaline-earth metal ions in dibutyl phthalate and the polymeric gelatin film was investigated. The treatment of the layers containing the ionophore mentioned with aqueous solutions of the corresponding salts in the presence of NaBPh4 as the phase transfer catalyst results in the extraction of the metal cation into the polymeric layer due to complex formation with crown-containing benzo[f]chromene. The complex formation is accompanied by changes in the spectroscopic characteristics of chromene in the closed and open forms and an increase in the lifetime of the merocyanine form. The effects obtained depend on the metal cation concentration in a solution and the time of layer treatment.