Peter K. Byers

The oxidative addition of lodomethane to [PdMe2(bpy)] and the X-ray structure of the organopalladium(IV) product fac-[PdMe3(bpy)l](bpy = 2,2′-bipyridyl)

Oxidative addition of iodomethane to dimethyl(2,2′-bipyridyl)palladium(II) in acetone has resulted in isolation of the first hydrocarbylpalladium(IV) complex, fac-trimethyl(2,2′-bipyridyl)iodopalladium(IV); the complex has been structurally characterized, and reductively eliminates ethane in solution to form methyl(2,2′-bipyridyl)idodpalladium(II).

Organometallic Chemistry of Palladium and Platinum with Poly(pyrazol-1-yl)alkanes and Poly(pyrazol-1-yl)borates

Publisher Summary This chapter covers two new areas of poly(pyrazol-1-yl)alkane chemistry—namely, organopalladium and organoplatinum chemistry and includes their comparisons. Palladium and platinum were involved in the early exploration of poly(pyrazo1-1-y1)borates and poly(pyrazo1-1-y1)alkanes as ligands, and these ligands have subsequently played key roles in the development of organopalladium and platinum chemistry. For example, among the more recent reports is account of allylpalladium chemistry directly related to the initial applications of these ligands. In addition to poly(pyrazol-1-yl)alkanes and -berates, closely related polydentate ligands containing at least one pyrazol-1-yl (pz) group are included, in particular, ligands containing the pyridin-2-yl (py) and N-methylimidazol-2-yl (mim) groups. The poly(pyrazol-1-yl)alkane ligands have been important in the development of the organometallic chemistry of palladium and platinum and recent new applications have included their role in stabilizing hydrocarbylpalladium(1V) compounds and in the synthesis of intramolecular coordination systems, containing tripodal ligands coordinated to platinum(1V).

The synthesis of tripodal nitrogen donor ligands and their characterization as PdIIMe2 and PdIIIMe derivatives

New tripod ligands containing pyridin-2-yl (py), N-methylimidazol-2-yl (mim), and pyrazol-l-y1 (pz) groups have been made by addition of 2-bromopyridine to deprotonated (py)(mim)CH2 or (mim)2CH2 to form (py)2(mim)CH and (py)(mim)2CH, or by simple condensation reactions of (pz)2CO with (mim)CHO or (py)CHO to form (pz)2(mim)CH and (pz)2(py)CH. The ligands may have general application in coordination and organometallic chemistry, especially bis(pyrazol-lyl)(pyridin-2-yl)methane [(pz)2(py)CH], which can be readily synthesized and is an unsymmetrical tripod closely related to (pz)3CH and (py)3CH. Dimethylpalladium( II) and methyl(iodo)palladium(II) complexes of the ligands have been isolated, and compared with complexes of (pz)3CH, (py)3CH, and (pz)4C.

Chemistry of polynuclear metal complexes with bridging carbene or carbene ligands. Part 108. Synthesis and reactions of the alkylidynetungsten complexes [W(CR)(CO)2{(F3B)C(pz)3}](R = Me or C6H4Me-4, pz = pyrazol-1-yl) and their use as reagents for preparing di-and tri-metal compounds

Treatment of thf (tetrahydrofuran) solutions of the salts [W(CR)(CO)2{HC(pz)3}][BF4][R = Me or C6H4Me-4, HC(pz)3= tris(pyrazol-1-yl)methane] with LiBu, followed by BF3·Et2O, affords the neutral alkylidynetungsten complexes [W(CR)(CO)2{(F3B)C(pz)3}]. The species with R = Me was also prepared from the reaction between [W(CMe)Br(CO)4] and Li[(F3B)C(pz)3] in thf. The compounds [W(CMe)(CO)2{(F3B)C(pz)3}] and [Pt(nb)(PMe2Ph)2](nb = norbornene = bicyclo[2.2.1]heptene) react in thf to yield the dimetal complex [WPt(µ-CMe)(CO)2(PMe2Ph)2{(F3B)C(pz)3}], and the latter with [AuR(tht)](R = Cl or C6F5, tht = tetrahydrothiophene) or CuCl in CH2Cl2, yields the trimetal species [WPtMR(µ3-CMe)(CO)2(PMe2Ph)2{(F3B)C(pz)3}](M = Au, R = Cl or C6F5; M = Cu, R = Cl), respectively. Addition of [Pt(cod)2](cod = cycloocta-1,5-diene) to a thf solution of [W(CMe)(CO)2{(F3B)C(pz)3}] gives a chromatographically separable mixture of the compounds [WPt(µ-CMe)(CO)2-(cod){(F3B)C(pz)3}], [W2Pt(µ-CMe)2(CO)4{(F3B)C(pz)3}2] and [WPt2(µ3-CMe)(CO)2(cod)2{(F3B)C-(pz)3}]. The complexes [WPt(µ-CC6H4Me-4)(CO)2(cod){(F3B)C(pz)3}] and [WPt2(µ3-CC6H4Me-4)-(CO)2(cod)2{(F3B)C(pz)3}] have been similarly obtained from [Pt(cod)2] and [W(CC6H4Me-4)(CO)2{(F3B)C(pz)3}]. Treatment of the latter with [Pt(nb)3] in thf affords the trimetal compound [W2Pt(µ-CC6H4Me-4)2(CO)4{(F3B)C(pz)3}2]. The NMR data (1H, 13C-{1H} and 31P-{1H}) for the new compounds are reported and discussed.

Chemistry of polynuclear metal complexes with bridging carbene or carbyne ligands. Part 106. Synthesis and reactions of the alkylidyne complexes [M(CR)(CO)2{(C6F5)AuC(pz)3}](M = WorMo, R = alkyloraryl, pz = pyrazol-1-yl); crystal structure of [WPtAU(C6F5)(µ3-CMe)(CO)2(PMe2Ph)2{(C6F5)AuC(pz)3}]

Treatment of the salts [M (CR)(CO)2{HC(pz)3}][BF4][M = W or Mo, R = alkyl or aryl, HC(pz)3= tris(pyrazol-1 -yl)methane] in thf (tetrahydrofuran) with NaOEt, followed by [Au(C6F5)(tht)](tht = tetrahydrothiophene), affords the neutral alkylidynemetal compounds [M(CR)(CO)2{(C6F5)AuC(pz)3}](M = W or Mo, R = C6H4Me-4; M = W, R = Me or C6H3Me2-2,6). The complexes (M = W, R = Me or C6H4Me-4) have been used to prepare several compounds containing heteronuclear metal–metal bonds, including [WAuX(µ-CMe)(CO)2{(C6F5)AuC(pz)3}](X = Cl or C6F5), [WCo2(µ3-CR)(CO)8{(C6F5)AuC(pz)3}], [WPt(µ-CR)(CO)2(PMe2Ph)2{(C6F5)AuC(pz)3}], and [W2Pt(µ-CR)2(CO)4{(C6F5)AuC(pz)3}2]. The cluster compound [WPtAu(C6F5)(µ3-CMe)(CO)2(PMe2Ph)2{(C6F5)AuC(pz)3}] has been synthesised by different routes, and its structure established by X-ray diffraction. The core of the molecule consists of a WPtAu triangle [W–Pt 2.798(2), W–Au 2.841(2), and Pt–Au 2.932(2)A] asymmetrically capped by an ethylidyne group [µ-C–W 2.06(3), µ-C–Pt 2.05(3), and µ-C–Au 2.31 (3)A]. The latter lies appreciably further from the Au atom than from the W or Pt atoms. The two carbonyl ligands semi-bridge the W–Pt [W–C–O 160(2)°] and W–Au [W–C–O 165(3)°] bonds. The Pt atom carries the PMe2Ph groups [P–Pt 2.26(1) and 2.32(1)A], and the Au atom is co-ordinated by the C6F5 group [C–Au 2.04(3)A]. The W atom is ligated by the three nitrogens of the (C6F5)AuC(pz)3 moiety (N–W average 2.21 A). The n.m.r. data (1H, 13C-{1H}, 31P-{1H}, and 19F-{1H}) for the new compounds are reported and discussed where appropriate.

Trimethylpalladium(IV) chemistry. Conformational and fluxional effects in related palladium(IV) and platinum(IV) complexes of flexible bidentate nitrogen donor ligands

Abstract Iodomethane reacts with palladium(II) complexes PdMe 2 (L 2 ), where L 2 is a flexible nitrogen donor ligand such as 1,1-bis(pyridin-2-yl)ethane [(py) 2 CHMe], to form unstable trimethylpalladium(IV) complexes characterized as fac -PdIMe 3 (L 2 ) by comparison of their variable temperature 1 H NMR spectra with those of stable trimethylplatinum(IV) analogues. The complexes fac -MIMe 3 {(py) 2 CHMe} occur as mixtures of isomers, with the chelate ring having the CH group adjacent to iodine in one isomer and adjacent to the methyl group trans to iodine in the other isomer. Complexes containing pyrazol-1-yl (pz) or N -methylimidazol-1-yl (mim) donors, fac -MIMe 3 (L 2 ) [L 2 = (pz) 2 CH 2 , (pz)(mim)CH 2 , and (py)(pz)CH 2 ] undergo fluxional behaviour involving inversion of the six-membered chelate rings.

Synthesis of the first organopalladium(IV) cations, including the first X-ray study of isostructural organopalladium(IV) and platinum(IV) complexes, [fac-MMe3{tris(pyrazol-1-yl)methane-N,N′,N′}]I

Stable organopalladium(IV) complexes [fac-PdMe3(L)]I (L = tridentate nitrogen donor ligand) are formed on oxidative addition of iodomethane to PdMe2(L); the tris (Pyrazol-1-yl)methane complex is isostructural with the platinum(IV) analogue.

Organopalladium(IV) chemistry: oxidative addition of organohalides to dimethylpalladium(II) complexes to form ethyl, σ-benzyl, and σ-allylpalladium(IV) complexes

The first examples of ethyl, σ-benzyl, and σ-allylpalladium(IV) complexes are formed on oxidative addition of organohalides to PdMe2{(pyridin-2-yl)bis(N-methylimidazol-2-yl)methane}[PdMe2{(py)(mim)2CH}]; the complexes [fac-PdRMe2{(py)(mim)2CH-N,N′,N′}]X (RX = Etl, PhCH2Br, CH2CHCH2Br) are stable at ambient temperature, with the cations present as two isomers, and benzyl bromide also forms the neutral complex fac-Pd(CH2Ph)Me2(bipy)Br on oxidative addition to PdMe2(2,2′-bipyridyl), but Etl and CH2CHCH2Br form transient PdIV species, detectable by 1H n.m.r. spectroscopy, prior to reductive elimination reactions.

Convenient synthetic routes to MePdII, Me2PdII, and Me3PdIV complexes. The crystal structure of the MePdII complex [MePd(2,2′-bipyridyl)(γ-picoline)]BF4

Abstract The pyridazine complex [Me2Pd(pyd)]n, stable as a solid on storage at ca. −20°C and obtained on reaction of trans-PdCl2(SMe2)2 pyridazine at low temperature, is an excellent precursor for the synthesis of Me2PdII and Me3PdIV complexes under mild conditions, in p Similarly, [MePd(SMe2)(μ-I)]2 is a suitable precursor for the synthesis of neutral and cationic MePdII complexes, including [MePd(2,2′-

Synthesis, spectroscopic, and structural studies of the methylpalladium(II) complexes [{PdMe(SMe2)X}2](X = Cl, Br, or I); crystal structure of trans-[{PdMe(SMe2)(µ-Cl)}2]

The complexes [{PdMe(SMe2)X}2](X = Cl, Br, or I) have been prepared by reaction of trans[Pd(SMe2)2X2] with halide-free methyl-lithium (X = Cl or Br), and reaction of trans-[Pd(SMe2)2Cl2] with methyl-lithium containing lithium iodide (X = I) in diethyl ether at –60 to –15 °C under nitrogen. Other synthetic routes to the bromo- and iodo-complexes are also described. The crystal structure of the chloro-complex [{PdMe(SMe2)(µ-Cl)}2] has been determined by single-crystal X-ray diffraction at 295 K and refined by least-squares methods to R= 0.025 for 1 914 independent ‘observed’ reflections [space group P21/n, a= 10.792(4), b= 7.373(2), c= 9.131(5)A, β= 109.03(3)°, and Z= 2]. The centrosymmetric dimeric molecules have trans stereochemistry with bridging chloro-groups and square-planar geometry for palladium(II). 1H N.m.r. and far-i.r. spectra, and molecular weight determinations are consistent with similar structures for the bromoand iodo-complexes.