Unusual neutral ligand coordination to arsenic and antimony trifluoride

The preparations and spectroscopic characterisation of the hydrolytically unstable As(III) complexes, [AsF(3)(OPR(3))(2)] (R = Me or Ph) and [AsF(3){Me(2)P(O)CH(2)P(O)Me(2)}] are described and represent the first examples of complexes of AsF(3) with neutral ligands. The crystal structure of [AsF(3){Me(2)P(O)CH(2)P(O)Me(2)}] contains dimers with bridging diphosphine dioxide, but there are also long contacts between the dimers to neighbouring phosphine oxide groups, completing a very distorted six-coordination at arsenic and producing a weakly associated polymer structure. The reaction of AsF(3) with OAsPh(3) affords Ph(3)AsF(2), and no arsine oxide complex was formed. Reaction of SbF(3) with OER(3) (R = Me or Ph, E = P or As), Me(2)P(O)CH(2)P(O)Me(2) and Ph(2)P(O)(CH(2))(n)P(O)Ph(2) (n = 1 or 2) in MeOH produces [SbF(3)(OER(3))(2)], [SbF(3){Me(2)P(O)CH(2)P(O)Me(2)}] and [SbF(3){Ph(2)P(O)(CH(2))(n)P(O)Ph(2)}] respectively. The X-ray structures reveal that the complexes contain square pyramidal SbF(3)O(2) cores with apical F and cis disposed pnictogen oxides. However, whilst [SbF(3)(OER(3))(2)] (R = Ph: E = P or As; R = Me: E = As) and [SbF(3){Ph(2)P(O)CH(2)P(O)Ph(2)}] are monomeric, [SbF(3){Me(2)P(O)CH(2)P(O)Me(2)}] is a dimer with bridging diphosphine dioxides producing a twelve-membered ring, and [SbF(3){Ph(2)P(O)(CH(2))(2)P(O)Ph(2)}] is a chain polymer with diphosphine dioxide bridges. In the OAsR(3) reactions with SbF(3), R(3)AsF(2) are also formed. Notably the Sb-O(P) bonds are shorter than As-O(P), despite the covalent radii (As < Sb), consistent with very weak coordination of the AsF(3). IR and multinuclear ((1)H, (19)F and (31)P) NMR data are reported and discussed. BiF(3) does not react with pnictogen oxide ligands under similar conditions and halide exchange of bismuth chloro complexes with Me(3)SnF gave BiF(3).     

Site selectivity and reversibility in the reactions of titanium hydrazides with Si-H, Si-X, C-X and H+ reagents: Ti=N(α) 1,2-silane addition, Nβ alkylation, Nα protonation and σ-bond metathesis

We report a combined experimental and computational comparative study of the reactions of the homologous titanium dialkyl- and diphenylhydrazido and imido compounds Cp*Ti{MeC(N(i)Pr)(2)}(NNR(2)) (R = Me (1) or Ph (2)) and Cp*Ti{MeC(N(i)Pr)(2)}(NTol) (3) with silanes, halosilanes, alkyl halides and [Et(3)NH][BPh(4)]. Compound 1 underwent reversible Si-H 1,2-addition to Ti=N(α) with RSiH(3) (experimental ΔH ca. -17 kcal mol(-1)), and irreversible addition with PhSiH(2)X (X = Cl, Br). DFT found that the reaction products and certain intermediates were stabilised by β-NMe(2) coordination to titanium. The Ti-D bond in Cp*Ti{MeC(N(i)Pr)(2)}(D){N(NMe(2))SiD(2)Ph} underwent σ-bond metathesis with BuSiH(3) and H(2). Compound 1 reacted with RR'SiCl(2) at N(α) to transfer both Cl atoms to Ti; 2 underwent a similar reaction. Compound 3 did not react with RSiH(3) or alkyl halides but formed unstable Ti=N(α) 1,2-addition or N(α) protonation products with PhSiH(2)X or [Et(3)NH][BPh(4)]. Compound 1 underwent exclusive alkylation at N(β) with RCH(2)X (R = H, Me or Ph; X = Br or I) whereas protonation using [Et(3)NH][BPh(4)] occurred at N(α). DFT studies found that in all cases electrophile addition to N(α) (with or without NMe(2) chelation) was thermodynamically favoured compared to addition to N(β).     

Isotope dilution analysis in the micro and submicro range by double-labelling and precipitation on paper

A new variation of isotope dilution analysis based on double labelling and carried out on filter paper is described. The determination of microgram and submicrogram amounts of silver (labelled with (110m)Ag) by precipitation with iodide (labelled with (131)I) and of calcium (labelled with (45)Ca) by precipitation with phosphate (labelled with (32)P) are given as examples. In the first example the two radio-elements ((110m)Ag and (131)I) are measured by gamma-spectrometry, in the second one ((45)Ca and(32)P) by a beta-absorption method. A number of results show the usefulness of the method.     

Ion-molecule reactions of gas-phase chromium oxyanions: CrxOyH z − + O2

Chromium oxyanions, Cr(x)O(y)H(z)(-), were generated in the gas-phase using a quadrupole ion trap secondary ion mass spectrometer (IT-SIMS), where they were reacted with O(2). Only CrO(2)(-) of the Cr(1)O(y)H(z)(-) envelope was observed to react with oxygen, producing primarily CrO(3)(-). The rate constant for the reaction of CrO(2)(-) with O(2) was approximately 38% of the Langevin collision constant at 310 K. CrO(3)(-), CrO(4)(-), and CrO(4)H(-) were unreactive with O(2) in the ion trap. In contrast, Cr(2)O(4)(-) was observed to react with O(2) producing CrO(3)(-) + CrO(3) via oxidative degradation at a rate that was approximately 15% efficient. The presence of background water facilitated the reaction of Cr(2)O(4)(-) + H(2)O to form Cr(2)O(5)H(2)(-); the hydrated product ion Cr(2)O(5)H(2)(-) reacted with O(2) to form Cr(2)O(6)(-) (with concurrent elimination of H(2)O) at a rate that was 6% efficient. Cr(2)O(5)(-) also reacted with O(2) to form Cr(2)O(7)(-) (4% efficient) and Cr(2)O(6)(-) + O (2% efficient); these reactions proceeded in parallel. By comparison, Cr(2)O(6)(-) was unreactive with O(2), and in fact, no further O(2) addition could be observed for any of the Cr(2)O(6)H(z)(-) anions. Generalizing, Cr(x)O(y)H(z)(-) species that have low coordinate, low oxidation state metal centers are susceptible to O(2) oxidation. However, when the metal coordination is >3, or when the formal oxidation state is > or =5, reactivity stops.     

Sigma-borane complexes of iridium: synthesis and structural characterization

Reaction of NaBH4 with (tBuPOCOP)IrHCl affords the previously reported complex (tBuPOCOP)IrH2(BH3) (1) (tBuPOCOP = kappa(3)-C6H3-1,3-[OP(tBu)2]2). The structure of 1 determined from neutron diffraction data contains a B-H sigma-bond to iridium with an elongated B-H bond distance of 1.45(5) A. Compound 1 crystallizes in the space group P1 (Z = 2) with a = 8.262 (5) A, b = 12.264 (5) A, c = 13.394 (4) A, and V = 1256.2 (1) A(3) (30 K). Complex 1 can also be prepared by reaction of BH3 x THF with (tBuPOCOP)IrH2. Reaction of (tBuPOCOP)IrH2 with pinacol borane gave initially complex 2, which is assigned a structure analogous to that of 1 based on spectroscopic measurements. Complex 2 evolves H2 at room temperature leading to the borane complex 3, which is formed cleanly when 2 is subjected to dynamic vacuum. The structure of 3 has been determined by X-ray diffraction and consists of the (tBuPOCOP)Ir core with a sigma-bound pinacol borane ligand in an approximately square planar complex. Compound 3 crystallizes in the space group C2/c (Z = 4) with a = 41.2238 (2) A, b = 11.1233 (2) A, c = 14.6122 (3) A, and V = 6700.21 (19) A(3) (130 K). Reaction of (tBuPOCOP)IrH2 with 9-borobicyclononane (9-BBN) affords complex 4. Complex 4 displays (1)H NMR resonances analogous to 1 and exists in equilibrium with (tBuPOCOP)IrH2 in THF solutions.     

C-H···π interactions in the CHBrF2···HCCH weakly bound dimer

The microwave spectra of four isotopologues of the CHBrF(2)···HCCH weakly bound dimer have been measured in the 6-18 GHz region using chirped-pulse and Balle-Flygare Fourier-transform microwave spectroscopy. Spectra of (13)CH(79)BrF(2) and (13)CH(81)BrF(2) monomers have also been measured, and spectroscopic constants are reported. Measurement of spectra for the (79)Br and (81)Br isotopologues of CHBrF(2) complexed with both (12)C(2)H(2) and (13)C(2)H(2) have allowed the determination of a structure with C(s) symmetry for this complex. CHBrF(2) interacts with the triple bond of acetylene via a C-H···π contact (R(H···π) = 2.670(8) ?) with the Br atom lying in the ab plane, located 3.293(40) ? from a hydrogen atom of the HCCH molecule. The structure of CHBrF(2)···HCCH has been compared with recently studied related acetylene complexes, including a comparison with (and further structural analysis of) the CHClF(2)···HCCH complex.     

Bis(tetrafluorophenyl)borane

The reaction of the Grignard reagent (p-C(6)F(4)H)MgBr with Me(2)SnCl(2) afforded the p-C(6)F(4)H transfer reagent Me(2)Sn(p-C(6)F(4)H)(2) (1). Subsequent reaction of 1 with BCl(3) led to the chloroborane (p-C(6)F(4)H)(2)BCl (2), which was converted to the borane [(p-C(6)F(4)H)(2)BH](2) (3) by treatment with the hydride source Me(2)SiHCl. By reaction of tetrafluoropyridine with i-PrMgCl followed by the in situ reaction with Me(2)SnCl(2), the stannane Me(2)Sn(C(5)F(4)N)(2) (4) could be obtained. However, this did not react with BCl(3). The resulting products were characterized by elemental analyses and NMR spectroscopy. Single crystal X-ray diffraction experiments were performed for compounds 1, 2 and 4. The crystal structure of the literature known compound Me(2)Sn(C(6)F(5))(2) (5) was determined and compared with structures of 1 and 4.     

Synthesis and structural variations of substituted phenylamide complexes of the heavy alkaline earth metals calcium, strontium and barium

Starting material KN(H)C(6)H(3)-2,6-F(2) was prepared via a transamination reaction from KNH(2) and 2,6-F(2)C(6)H(3)NH(2) in THF and crystallized from 1,4-dioxane (diox) as the three-dimensional polymer [(diox)(1.5)K{N(H)-2,6-F(2)C(6)H(3)}.diox(0.5)](infinity) (1). The metathesis reaction of (THF)(4)CaI(2) with KN(Me)Ph in THF yields monomeric (THF)(4)Ca[N(Me)Ph](2) (2) with a nearly linear N-Ca-N moiety of 179.84(8) degrees . The metathesis reaction of (THF)(4)CaI(2) with KN(H)Mes yields trinuclear (THF)(6)Ca(3)[N(H)Mes](6) (3) with a linear Ca(3) fragment and bridging 2,4,6-trimethylphenylamido groups. The reaction of 1 with (THF)(4)CaI(2) gives dinuclear (THF)(5)Ca(2)[N(H)-2,6-F(2)C(6)H(3)](4).2THF (4) with three bridging and one terminally bound 2,6-difluorophenylamide. A similar reaction of (THF)(5)SrI(2) with KN(H)-2,6-F(2)C(6)H(3) yields dinuclear (THF)(6)Sr(2)[N(H)-2,6-F(2)C(6)H(3)](3)I.THF (5) in which the iodide anion binds terminally. This iodide ligand cannot be substituted as easily by excess KN(H)-2,6-F(2)C(6)H(3). The metathesis reaction of (THF)(5)BaI(2) with KN(H)-2,6-F(2)C(6)H(3) leads to the formation of [(THF)(2)Ba{N(H)-2,6-F(2)C(6)H(3)}(2)](infinity) (6) which crystallizes as a one-dimensional polymer with bridging 2,6-difluorophenylamide anions and additional Ba-F-bonds.     

Formation and reactivity of a porphyrin iridium hydride in water: acid dissociation constants and equilibrium thermodynamics relevant to Ir-H, Ir-OH, and Ir-CH2- bond dissociation energetics

Aqueous solutions of group nine metal(III) (M = Co, Rh, Ir) complexes of tetra(3,5-disulfonatomesityl)porphyrin [(TMPS)M(III)] form an equilibrium distribution of aquo and hydroxo complexes ([(TMPS)M(III)(D(2)O)(2-n)(OD)(n)]((7+n)-)). Evaluation of acid dissociation constants for coordinated water show that the extent of proton dissociation from water increases regularly on moving down the group from cobalt to iridium, which is consistent with the expected order of increasing metal-ligand bond strengths. Aqueous (D(2)O) solutions of [(TMPS)Ir(III)(D(2)O)(2)](7-) react with dihydrogen to form an iridium hydride complex ([(TMPS)Ir-D(D(2)O)](8-)) with an acid dissociation constant of 1.8(0.5) × 10(-12) (298 K), which is much smaller than the Rh-D derivative (4.3 (0.4) × 10(-8)), reflecting a stronger Ir-D bond. The iridium hydride complex adds with ethene and acetaldehyde to form organometallic derivatives [(TMPS)Ir-CH(2)CH(2)D(D(2)O)](8-) and [(TMPS)Ir-CH(OD)CH(3)(D(2)O)](8-). Only a six-coordinate carbonyl complex [(TMPS)Ir-D(CO)](8-) is observed for reaction of the Ir-D with CO (P(CO) = 0.2-2.0 atm), which contrasts with the (TMPS)Rh-D analog which reacts with CO to produce an equilibrium with a rhodium formyl complex ([(TMPS)Rh-CDO(D(2)O)](8-)). Reactivity studies and equilibrium thermodynamic measurements were used to discuss the relative M-X bond energetics (M = Rh, Ir; X = H, OH, and CH(2)-) and the thermodynamically favorable oxidative addition of water with the (TMPS)Ir(II) derivatives.     

Chiral bisphosphinite metalloligands derived from a P-chiral secondary phosphine oxide

Interaction of PdCl(2)(MeCN)(2) with 2 equiv of (S(P))-(t)BuPhP(O)H (1H) followed by treatment with Et(3)N gave [Pd((1)(2)H)](2)(micro-Cl)(2) (2). Reaction of 2 with Na[S(2)CNEt(2)] or K[N(PPh(2)S)(2)] afforded Pd[(1)(2)H](S(2)CNEt(2)) (3) or Pd[(1)(2)H)[N(PPh(2)S)(2)] (4), respectively. Treatment of 3 with V(O)(acac)(2) (acac = acetylacetonate) and CuSO(4) in the presence of Et(3)N afforded bimetallic complexes V(O)[Pd(1)(2)(S(2)CNEt(2))](2) (5) or Cu[Pd(1)(2)(S(2)CNEt(2))](2) (6), respectively. X-ray crystallography established the S(P) configuration for the phosphinous acid ligands in 3 and 6, indicating that 1H binds to Pd(II) with retention of configuration at phosphorus. The geometry around Cu in 6 is approximately square planar with the average Cu-O distance of 1.915(3) A. Treatment of 2 with HBF(4) gave the BF(2)-capped compound [Pd((1)(2)BF(2))](2)(micro-Cl)(2) (7). The solid-state structure of 7 containing a PdP(2)O(2)B metallacycle has been determined. Chloride abstraction of 7 with AgBF(4) in acetone/water afforded the aqua compound [Pd((1)(2)BF(2))(H(2)O)(2)][BF(4)] (8) that reacted with [NH(4)](2)[WS(4)] to give [Pd((1)(2)BF(2))(2)](2)[micro-WS(4)] (9). The average Pd-S and W-S distances in 9 are 2.385(3) and 2.189(3) A, respectively. Treatment of [(eta(6)-p-cymene)RuCl(2)](2) with 1H afforded the phosphinous acid adduct (eta(6)-p-cymene)RuCl(2)(1H) (10). Reduction of [CpRuCl(2)](x)() (Cp = eta(5)-C(5)Me(5)) with Zn followed by treatment with 1H resulted in the formation of the Zn(II) phosphinate complex [(CpRu(eta(6)-C(6)H(5)))(t)BuPO(2))](2)(ZnCl(2))(2) (11) that contains a Zn(2)O(4)P(2) eight-membered ring.     

Chelate bis(imino)pyridine cobalt complexes: synthesis, reduction, and evidence for the generation of ethene polymerization catalysts by Li+ cation activation

Treatment of the bis(iminobenzyl)pyridine chelate Schiff-base ligand 8 (ligPh) with FeCl2 or CoCl2 yielded the corresponding (ligPh)MCl2 complexes 9 (Fe) and 10 (Co). The reaction of 10 with methyllithium or "butadiene-magnesium" resulted in reduction to give the corresponding (ligPh)Co(I)Cl product 11. Similarly, the bis(aryliminoethyl)pyridine ligand (ligMe) was reacted with CoCl2 to yield (ligMe)CoCl2 (12). Reduction to (ligMe)CoCl (13) was effected by treatment with "butadiene-magnesium". Complex 13 reacted with Li[B(C6F5)4] in toluene followed by treatment with pyridine to yield [(ligMe)Co+-pyridine] (15). The reaction of the Co(II) complexes 10 or 12 with ca. 3 molar equiv of methyllithium gave the cobalt(I) complexes 16 and 17, respectively. Treatment of the (ligMe)CoCH3 (17) with Li[B(C6F5)4] gave a low activity ethene polymerization catalyst. Likewise, complex 16 produced polyethylene (activity = 33 g(PE) mmol(cat)(-1) h(-1) bar(-1) at room temperature) upon treatment with a stoichiometric amount of Li[B(C6F5)4]. A third ligand (lig(OMe)) was synthesized featuring methoxy groups in the ligand backbone (22). Coordination to FeCl2 and CoCl2 yielded the desired compounds 23 and 24. Reaction with MeLi gave (ligOMe)CoMe (25/26). Treatment of 25/26 with excess B(C6F5)3 gave the eta6-arene cation complex 27, where one Co-N linkage was cleaved. Activation of 25/26 with Li[B(C6F5)4] again gave a catalytically active species.     

Conformation of 2-aminomethylpyrrolidine and 2-aminomethylpiperidine in ternary platinum(II) complexes: regulation of conformation of the diamine by the coexisting ligand

Square-planar complexes with the formula [Pt(L(2))(L(1))](X)(2) x nH(2)O, where L(1) is S-2-aminomethylpyrrolidine (S-pyrda) or 2-aminomethylpiperidine (pipda) and L(2) is diammine (X=Cl), cyclobutane-1,1-dicarboxylato (cbdca) (X=none), 2,2'-bipyridine (bpy) (X=NO(3)), or 1,10-phenanthroline (phen) (X=Cl), were prepared and the nature of the coordination of L(1) was examined by (1)H-NMR spectroscopy and X-ray crystallography. These 2-aminomethylazacycloalkane derivatives form five-membered chelate rings condensed with an azacycloalkane ring in cis- or trans-configurations. The (1)H-NMR spectrum of complexes with S-pyrda as L(1) were consistent with cis-condensed rings in an S(N) conformation with any of L(2) group. However, (1)H-NMR spectra of the complexes with pipda as L(1) indicated trans-fused successive rings for the diammine and cbdca as L(2), but spectra for bpy and phen as L(2) were consistent with a conformation having cis-fused successive rings. X-Ray crystallography data for the two complexes with pipda as L(1) and cbdca (1) and bpy (2) as L(2) confirms the different coordination behavior in the solid state.     

The "missing link": the gas-phase generation of platinum-methylidyne clusters Pt(n)CH+ (n=1, 2) and their reactions with hydrocarbons and ammonia

Electrospray ionization (ESI) of tetrameric platinum(II) acetate, [Pt(4)(CH(3)COO)(8)], in methanol generates the formal platinum(III) dimeric cation [Pt(2)(CH(3)COO)(3)(CH(2)COO)(MeOH)(2)](+), which, upon harsher ionization conditions, sequentially loses the two methanol ligands, CO(2), and CH(2)COO to form the platinum(II) dimer [Pt(2)(CH(3)COO)(2)(CH(3))](+). Next, intramolecular sequential double hydrogen-atom transfer from the methyl group concomitant with the elimination of two acetic acid molecules produces Pt(2)CH(+) from which, upon even harsher conditions, PtCH(+) is eventually generated. This degradation sequence is supported by collision-induced dissociation (CID) experiments, extensive isotope-labeling studies, and DFT calculations. Both PtCH(+) and Pt(2)CH(+) react under thermal conditions with the hydrocarbons C(2)H(n) (n=2, 4, 6) and C(3)H(n) (n=6, 8). While, in ion-molecule reactions of PtCH(+) with C(2) hydrocarbons, the relative rates decrease with increasing n, the opposite trend holds true for Pt(2)CH(+). The Pt(2)CH(+) cluster only sluggishly reacts with C(2)H(2), but with C(2)H(4) and C(2)H(6) dihydrogen loss dominates. The reactions with the latter two substrates were preceded by a complete exchange of all of the hydrogen atoms present in the adduct complex. The PtCH(+) ion is much less selective. In the reactions with C(2)H(2) and C(2)H(4), elimination of H(2) occurs; however, CH(4) formation prevails in the decomposition of the adduct complex that is formed with C(2)H(6). In the reaction with C(2)H(2), in addition to H(2) loss, C(3)H(3)(+) is produced, and this process formally corresponds to the transfer of the cationic methylidyne unit CH(+) to C(2)H(2), accompanied by the release of neutral Pt. In the ion-molecule reactions with the C(3) hydrocarbons C(3)H(6) and C(3)H(8), dihydrogen loss occurs with high selectivity for Pt(2)CH(+), but in the reactions of these substrates with PtCH(+) several reaction routes compete. Finally, in the ion-molecule reactions with ammonia, both platinum complexes give rise to proton transfer to produce NH(4)(+); however, only the encounter complex generated with PtCH(+) undergoes efficient dehydrogenation of the substrate, and the rather minor formation of CNH(4)(+) indicates that C-N bond coupling is inefficient.     

Transfer of amido groups from isolated rhodium(I) amides to alkenes and vinylarenes

The reaction of monomeric and dimeric rhodium(I) amido complexes with unactivated olefins to generate imines is reported. Transamination of {(PEt(3))(2)RhN(SiMePh(2))(2)} (1a) or its -N(SiMe(3))(2) analogue 1b with p-toluidine gave the dimeric [(PEt(3))(2)Rh(mu-NHAr)](2) (Ar = p-tolyl) (2a) in 80% isolated yield. Reaction of 2a with PEt(3) generated the monomeric (PEt(3))(3)Rh(NHAr) (Ar = p-tolyl) (3a). PEt(3)-ligated arylamides 2a and 3a reacted with styrene to transfer the amido group to the olefin and to form the ketimine Ph(Me)C=N(p-tol) (4a) in 48-95% yields. The dinuclear amido hydride (PEt(3))(4)Rh(2)(mu-NHAr)(mu-H) (Ar = p-tolyl) (5a) was formed from reaction of 2a in 95% yield, and a mixture of this dimeric species and the (PEt(3))(n)RhH complexes with n = 3 and 4 was formed from reaction of 3a in a combined 75% yield. Propene reacted with 2a to give Me(2)C=N(p-tol) (4b) and 5a in 90 and 57% yields. Propene also reacted with 3a to give 4b and 5a in 65 and 94% yields. Analogues of 2a and 3a with varied electronic properties also reacted with styrene to form the corresponding imines, and moderately faster rates were observed for reactions of electron-rich arylamides. Kinetic studies of the reaction of 3a with styrene were most consistent with formation of the imine by migratory insertion of olefin into the rhodium-amide bond to generate an aminoalkyl intermediate that undergoes beta-hydrogen elimination to generate a rhodium hydride and an enamine that tautomerizes to the imine.     

1-[Hydroxy(sulfonyloxy)iodo]-1H,1H-perfluoroalkanes: Stable, Fluoroalkyl Analogs of Koser's Reagent

1-[Hydroxy(sulfonyloxy)iodo]-1H,1H-perfluoroalkanes 3 [R(f)CH(2)I(OH)OSO(2)R; R = CH(3), CF(3), p-CH(3)C(6)H(4), R(f) = CF(3), C(2)F(5)] can be prepared in two steps from the appropriate iodofluoroalkanes by oxidation with peroxytrifluoroacetic acid and subsequent reaction with TsOH, MsOH, or Me(3)SiOTf. The tosylate derivative 3a reacts with silyl enol ethers under mild conditions to give the respective alpha-(tosyloxy) ketones. A similar reaction of cyclohexene furnishes cis-1,2-bis(tosyloxy)cyclohexane as the major product. Triflates 3c,f react with (trimethylsilyl)arenes under mild conditions to afford the respective (fluoroalkyl) (aryl)iodonium triflates 7, while the analogous reaction with alkynyltrimethylsilanes leads to novel (fluoroalkyl)(alkynyl)iodonium salts 8.     

Oxidation by oxygen and sulfur of Tin(IV) derivatives containing a redox-active o-amidophenolate ligand

Oxidation of tin(IV) o-amidophenolate complexes [Sn(ap)Ph(2)] (1) and [Sn(ap)Et(2)(thf)] (2) (ap=dianion of 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-iminobenzoquinone (ImQ)) with molecular oxygen and sulfur in toluene solutions was investigated. The reaction of oxygen with 1 at room temperature forms a paramagnetic derivative [Sn(isq)(2)Ph(2)] (3) (isq=radical anion of ImQ) and diphenyltin(IV) oxide [{Ph(2)SnO}(n)]. Interaction of 1 with sulfur gives another monophenyl-substituted paramagnetic tin(IV) complex, [Sn(ap)(isq)Ph] (4), and the sulfide, [Ph(3)Sn](2)S. The oxidation of 2 with oxygen and with sulfur proceeds through the derivative [Sn(isq)(2)Et(2)] (7), which undergoes alkyl elimination to give two new tin(IV) compounds, [Sn(ap)(isq)Et] (5) and [Sn(ap)(EtImQ)Et] (6) (EtImQ=2,4-di-tert-butyl-6-(2,6-diisopropylphenylimino)-3-ethylcyclohexa-1,4-dienolate ligand), respectively, along with the corresponding alkyltin(IV) oxide and sulfide. Complexes 3-5 and 7 were studied by EPR spectroscopy. The structures of 3, 4 and 6 were investigated by X-ray analysis.     

6-Coordinate tungsten(VI) tris-n-isopropylanilide complexes: products of terminal oxo and nitrido transformations effected by main group electrophiles

The nitridotungsten(vi) complex NW(N[i-Pr]Ar)(3) (-N, Ar = 3,5-Me(2)C(6)H(3)) reacts with (CF(3)C(O))(2)O followed by ClSiMe(3) to give the isolable trifluoroacetylimido-chloride complex -(NC(O)CF(3))Cl, with oxalyl chloride to give cyanate-dichloride -(OCN)(Cl)(2), and with PCl(5) to give trichlorophosphinimide-dichloride -(NPCl(3))(Cl)(2). The oxo-chloride complex -(O)Cl, obtained from -N upon treatment with pivaloyl chloride, reacts with PCl(5) to give trichloride -(Cl)(3). Synthetic and structural details are reported for the new tungsten trisanilide derivatives.     

The first acetimino complexes of Rh(III). 4-imino-2-methylpentan-2-amino-Rh(III) complexes through metal-assisted intramolecular aldol-type condensation of two acetimino ligands

[Rh(Cp)Cl(mu-Cl)](2) (Cp = pentamethylcyclopentadienyl) reacts (i) with [Au(NH=CMe(2))(PPh(3))]ClO(4) (1:2) to give [Rh(Cp)(mu-Cl)(NH=CMe(2))](2)(ClO(4))(2) (1), which in turn reacts with PPh(3) (1:2) to give [Rh(Cp)Cl(NH=CMe(2))(PPh(3))]ClO(4) (2), and (ii) with [Ag(NH=CMe(2))(2)]ClO(4) (1:2 or 1:4) to give [Rh(Cp)Cl(NH=CMe(2))(2)]ClO(4) (3) or [Rh(Cp)(NH=CMe(2))(3)](ClO(4))(2).H(2)O (4.H(2)O), respectively. Complex 3 reacts (i) with XyNC (1:1, Xy = 2,6-dimethylphenyl) to give [Rh(Cp)Cl(NH=CMe(2))(CNXy)]ClO(4) (5), (ii) with Tl(acac) (1:1, acacH = acetylacetone) or with [Au(acac)(PPh(3))] (1:1) to give [Rh(Cp)(acac)(NH=CMe(2))]ClO(4) (6), (iii) with [Ag(NH=CMe(2))(2)]ClO(4) (1:1) to give 4, and (iv) with (PPN)Cl (1:1, PPN = Ph(3)P=N=PPh(3)) to give [Rh(Cp)Cl(imam)]Cl (7.Cl), which contains the imam ligand (N,N-NH=C(Me)CH(2)C(Me)(2)NH(2) = 4-imino-2-methylpentan-2-amino) that results from the intramolecular aldol-type condensation of the two acetimino ligands. The homologous perchlorate salt (7.ClO(4)) can be prepared from 7.Cl and AgClO(4) (1:1), by treating 3 with a catalytic amount of Ph(2)C=NH, in an atmosphere of CO, or by reacting 4with (PPN)Cl (1:1). The reactions of 7.ClO(4) with AgClO(4) and PTo(3) (1:1:1, To = C(6)H(4)Me-4) or XyNC (1:1:1) give [Rh(Cp)(imam)(PTo(3))](ClO(4))(2).H(2)O (8) or [Rh(Cp)(imam)(CNXy)](ClO(4))(2) (9), respectively. The crystal structures of 3 and 7.Cl have been determined.     

2-取代的6-溴甲基-4(3H)-喹唑啉酮的合成

2-取代的6-溴甲基-4(3H)-喹唑啉酮的合成;4(3H)-喹唑啉酮;苯并噁嗪酮;N-溴代琥珀酰亚胺; 合成     

Mode selective tunneling dynamics observed by high resolution spectroscopy of the bending fundamentals of 14NH2D and 14ND2H

High resolution (0.004 and 0.01 cm(-1) instrumental bandwidth) interferometric Fourier transform infrared spectra of (14)NH2D and (14)ND2H were measured on a Bomem DA002 spectrometer in a supersonic jet expansion and at room temperature. We report the analysis of the bending fundamentals of (14)NH2D with term values Tv(s)=1389.9063(2) cm(-1) and Tv(a)=1390.4953(2) cm(-1) for the nu(4b) fundamental and Tv(s)=1605.6404(7) cm(-1) and Tv(a)=1591.0019(7) cm(-1) for the nu(4a) fundamental, and of (14)ND2H with term values of Tv(s)=1233.3740(2) cm(-1) and Tv(a)=1235.8904(2) cm(-1) for the nu(4a) fundamental and Tv(s)=1461.7941(9) cm(-1) and Tv(a)=1461.9918(19) cm(-1) for the nu(4b) fundamental. In all cases Tv(s) gives the position of the symmetric inversion sublevel (with positive parity) and Tv(a) the position of the antisymmetric inversion sublevel (with negative parity). The notation for the fundamentals nu(4a) and nu(4b) is chosen by correlation with the degenerate nu(4) mode in the C(3v) symmetric molecules NH3 and ND3. The degeneracy is lifted in Cs symmetry and a indicates the symmetric, b the antisymmetric normal mode with respect to the Cs symmetry plane in NH2D and ND2H. Assignments were established with certainty by means of ground state combination differences. About 20 molecular parameters of the effective S-reduced Hamiltonian could be determined accurately for each fundamental. In particular, the effect of Fermi resonances of the 2nu(2) overtone with the nu(4a) bending mode was observed, leading to an increased inversion splitting in the case of ND2H and to a strongly increased inversion splitting and an inverted order of the two inversion levels in NH2D. Rotational perturbations observed with the nu(4b) bending fundamentals are probably due to Coriolis interactions with the inversion overtone 2nu(2). The results are important for understanding isotope effects on the inversion in ammonia as well as its selective catalysis and inhibition by excitation of different vibrational modes, as treated by quantum dynamics on high dimensional potential hypersurfaces of this molecule.