Presence Of KPF6 Research Articles

Chemistry of polynuclear metal complexes with bridging carbene or carbyne ligands. Part 74. Salts of the anions [W(CR)(CO)2(η5-C2B9H9Me2)]–(R = C6H4Me-2 or C6H3Me2-2,6) as reagents for the synthesis of compounds with heteronuclear metal–metal bonds: crystal structure of [NEt4][FeW(µ-CC6H3Me2-2,6)(CO)5(η5-C2B9H9Me2)

The salts [X][W(CR)(CO)2(η5-C2B9H9Me2)](X = NEt4, R = C6H4Me-2 or C6H3Me2-2,6; X = PPh4, R = C6H3Me2-2,6) have been prepared, and used to synthesise a variety of compounds containing heteronuclear metal–metal bonds. Thus treatment of [NEt4][W(CR)(CO)2(η5-C2B9H9Me2)] with [AuCl(PPh3)] in thf (tetrahydrofuran), in the presence of KPF6, affords the dimetal compounds [AuW(µ-CR)(CO)2(PPh3)(η5-C2B9H9Me2)]. The reaction between [Pt(cod)2](cod = cyclo-octa-1,5-diene) and [PPh4][W(CC6H3Me2-2,6)(CO)2(η5-C2B9H9Me2)] affords the salt [PPh4][PtW(µ-CC6H3Me2-2,6)(CO)2(cod)(η5-C2B9H9Me2)]. The latter with [AuCl(PPh3)] in thf, in the presence of TIPF6, yields the trimetal compound [AuPtW(µ-CC6H3Me2-2,6)(CO)2(PPh3)(cod)(η5-C2B9H9Me2)]. Treatment of [NEt4][W(CR)(CO)2(η5-C2B9H9Me2)](R = C6H4Me-2) with [Fe3(CO)12] in thf affords a mixture of the compounds [NEt4][FeW(µ-CR)(CO)5(η5-C2B9H9Me2)], [NEt4][FeW{µ-CH(R)}(µ-σ:η5-C2B9H8Me2)(µ-CO)(CO)5], and [NEt4][Fe2W(µ3-CR)(µ3-σ:σ′:η5-C2B9H7Me2)(CO)8]. A similar reaction with [NEt4][W(CC6H3Me2-2,6)(CO)2(η5-C2B9H9Me2)] gives [NEt4][FeW(µ-CC6H3Me2-2,6)(CO)5(η5-C2B9H9Me2)] as the only iron–tungsten compound. The structure of the latter has been established by X-ray diffraction. The Fe–W bond [2.600(1)A] is spanned by the CC6H3Me2-2,6 group [µ-C–Fe 1.891(5) and µ-C–W 1.976(6)A]. The iron atom is ligated by three essentially orthogonal CO groups. The tungsten atom is co-ordinated by the pentagonal face of the nido-icosahedral fragment C2B9H9Me2, and by two CO groups, one of which semi-bridges the metal–metal bond [W–C–O 165.4(6)°]. The reaction between [PPh4][W(CR)(CO)2(η5-C2B9H9Me2)](R = C6H3Me2-2,6) and [Ru(CO)(NCMe)2(η-C5H5)][BF4] in CH2Cl2 gives the dimetal compound [RuW(µ-CR)(CO)3(η-C5H5)(η5-C2B9H9Me2)] which has an exopolyhedral B–H⇀Ru three-centre bond. The n.m.r. spectra (1H, 13C-{1H}, 11B-{1H}, and 31P-{1H}) of the new compounds are discussed in relation to their structures.

ChemInform Abstract: Carbon ‐ Chlorine Bond Activation in 2‐Chloromethylallyl Complexes of Platinum(II).

AbstractTreatment of the Pt(0) complex (I) with 3‐chloro‐2‐chloromethylprop‐1‐ene (II) and KPF6 affords the n3‐(2‐chloromethyl)allyl‐Pt(II) complex (IIIa).

Synthesis of mono and binuclear carbonyl complexes of manganese with cyanide or thiocyanate ligands. X-ray crystal structure of [{ fac-Mn(CO) 3(phen)} 2(μ-CN)]PF 6

The neutral complexes cis-trans-[MnX(CO) 2(bipy)- (P(OPh) 3)] (X=I, CN or SCN) have been prepared by nucleophilic substitution of P(OPh) 3 by X − in the cationic complex cis-trans-[Mn(CO) 2(bipy)- (P(OPh) 3) 2] +, or, in the case of X=CN, by reacting the iodo-dicarbonyl with AgCN. The cyanide complex reacts with MeI in the presence of KPF 6 or with HBF 4{dEt 2O (of BF 3}dEt 2O) to give respectively the cationic CNMe or the neutral CNBFF 3 derivative. The cyanide species fac-[Mn(CN)(CO) 3( N N )] ( N N =bipy or phen) and cis-trans-[Mn(CN)(CO) 2(bipy)(P(OPh) 3)] react at room temperature with fac- [MnBr(CO) 3( N N )] or cis-trans-[MnI(CO) 2(bipy) P(OPh) 3)] in the presence of TlPF 6 to give the corresponding cationic cyanide-bridged complexes [{Mn} aCN{Mn} b] + for {Mn} a or {Mn} b  Mn(CO) 3( N N ) or Mn(CO) 2(bipy)(P(OPh) 3). In the same way the salt [ fac-Mn(CO) 3(bipy) 2(/μ-SCN)]- PF 6 can be prepared from fac-[Mn(NCSXCO) 3(bipy)] and fac-[MnBr(CO) 3(bipy)]. The structure of the compound [ fac-Mn(CO) 3(phen) 2(μ-CN)]PF 6 has been established by X-ray diffraction. The reaction of the cyanide bridged complexes with HBF 4·Et 2O is also discussed.

Reactivity of quadruply bonded dimolybdenum(II) complexes with alkyl isocyanides: Mo-Mo bond cleavage or retention?

The quadruply-bonded dimolybdenum(II) complexes Mo 2(μ-dppm) 2X 4 (X = Br or I) can be prepared in high yield from Mo 2(μ-dppm) 2Cl 4 (dppm = Ph 2PCH 2PPh 2) via simple halide-exchange reactions (using NaX in acetone). The complexes Mo 2(μ-dppm) 2X 4 (X = Cl, Br or I) react with one equivalent of RNC (R = i-Pr or t-Bu) in the presence of TlPF 6 (in THF) or KPF 6 (in acetone) to give [Mo 2X 3(dppm) 2(CNR)]PF 6, the first examples of multiply bonded Mo 4+ 2 complexes that contain coordinated π-acceptor RNC ligands. The reactions of Mo 2(μ-dppm) 2X 4 with an excess of RNC lead to seven-coordinate mononuclear cations [MoX(dppm)(CNR) 4] +, which are in turn converted into [Mo(CNR) 5(dppm)] 2+ and thence [Mo(CNR) 7] 2+. The significance of these results, insofar as they relate to the cleavage of mixed halide-phosphine complexes of dimolybdenum(II) by isocyanides and the substitution chemistry of [Mo(CNR) 7](PF 6) 2 by phosphine ligands, are discussed. Comparisons are made with related chemistry of dinuclear and mononuclear molybdenum(II) complexes that contain bidentate nitrogen donors such as 2,2′-bipyridine, 1,10-phenanthroline and 1,4-disubstituted diaza-1,3-butadienes. The reactions between cis-Mo 2(mhp) 2Cl 2(PMePh 2) 2 (mhp is the anion of 2-hydroxy-6-methylpyridine) and t-BuNC (in the presence of KPF 6) result in the formation of mixtures of Mo 2(mhp) 4 and [Mo(CN- t-Bu) 5(PMePh 2) 2](PF 6) 2

Mixed alkyl isocyanide-1,4-diaza-1,3-butadiene complexes of molybdenum(II) and tungsten(II)

The reactions of M(CO) 4(R′-DAB) (M = Mo) or W; R′-DAB = R′-NCHCHNR′ (R′ = i-propyl, t-butyl, or cyclohexyl) with SnCl 4 in dichloromethane solution result in the formation, in high yield, of the orange, diamagnetic, seven-coordinate oxidative-addition products M(CO) 3(R′-DAB)(SnCl 3)Cl. The reactions of Mo(CO) 3(R′-DAB)(SnCl 3)Cl (R′ = i-Pr or Cy) with an excess of alkyl isocyanide RNC (R = CHMe 2, CMe 3, or C 6H 11) in the presence of KPF 6 lead to the formation of [Mo(CNR) 4(R′-DAB)Cl]PF 6 or [Mo(CNR) 5(R′-DAB)](PF 6) 2 depending upon the reaction stoichiometry and reaction conditions. The monocationic chloro species are converted to [Mo(CNR) 5(R′-DAB)](PF 6) 2 upon reflux with the stoichiometric amount of RNC. Under similar reactions conditions M(CO) 3(t-Bu-DAB)(SnCl 3)Cl (M = Mo or W) derivatives react with alkyl isocyanides with the reductive-elimination of the elements of SnCl 4 and the formation of octahedral M(CO) 3(CNR)(t-Bu-DAB). The dark red compounds [Mo(CNCMe 3) 5(R′-DAB)](PF 6) 2 (R′ = i-Pr or Cy) react readily with cyanide ions at ambient temperatures in methanol to yield [Mo(CNCMe 3) 4(R′-DAB)(CN)]PF 6. Attempts to thermally dealkylate the parent complexes [Mo(CNCMe 3) 5(R′-DAB)](PF 6) 2 (R′ = i-Pr or Cy) to these same cyano species were unsuccessful.

New isocyanide complexes of chromium derived from ethanolic solutions of chromium(II)

Treatment of ethanolic solutions of chromium(II) which are derived from the reduction of CrCl 3 · 6H 2O solutions) with excess phenyl isocyanide in the presence of KPF 6 affords the complex [Cr(CNPh) 5 Cl]PF 6. Under similar conditions, p-tolyl isocyanide yields the chromium(I) complex [Cr(CN- p-tol) 6PF 6. The paramagnetic, yellow-green compound [Cr(CNPh) 5 Cl]PF 6 decomposes in dichloromethane solution to yield the chromium(II) species [Cr(CNPh) 6](PF 6) 2. Treatment of dichloromethane solutions of [Cr(CNPh) 5 Cl]PF 6 with tertiary phosphines PR 3 (PR 3 = P-n-BU 3, P-n-Pr 3, PEt 3 or PEt 2 Ph) and with 1,2-bis(diphenylphosphino)ethane (dppe) gives paramagnetic trans-[Cr(CNPh) 4(PR 3)Cl]PF 6 and [Cr(CNPh) 3 (dppe)Cl]PF 6. However, bis(diphenylphosphino)methane (dppm) reacts with [Cr(CNPh) 5 Cl]PF 6 to yield the diamagnetic, seven-coordinate complex [Cr[CNPh) 5(dppm)(PF 6 2. In the presence of excess P(OR) 3 (R = Me or Et), ethanolic chromium(II) solutions and PhNC react to form [Cr(CNPh) 5 Cl]PF 6 whereas amines and phosphines lead to the formation of the homoleptic 18-electron compound Cr(CNPh) 6.

Redox Reactions Of Polyhydride Complexes of Rhenium: electrochemistry and Reactions With Alkyl Isocyanides

The dark red octahydride complex of dirhenium, Re 2H 8(PPh 3) 4, undergoes a reversible one-electron oxidation to the blue mono-cation [Re 2H 8(PPh 3) 4] + ( E buit;1 2 −0.24 V vs. SCE by cyclic voltammetry). The X-band ESR spectrum of a dichloromethane glass (−160°C) containing the monocation is in accord with the HOMO being a delocalized metal-based orbital. Treatment of the heptahydrides ReH 7(PR 3) 2 (PR 3 = PPh 3 or PEtPh 2) with C 6H 11NC or Me 3CNC in the presence of KPF 6 leads to the elimination of hydrogen and the formation of [Re(CNR) 4(PR 3) 2]PF 6. Electrochemical oxidation of ReH 5(PPh 3) 2L (L = PPh 3, PEt 2Ph, pyridine, piperidine or cyclohexylamine) activities these molecules to attack by RNC to afford rhenium(I) species