Iain Moore

Proton-induced dimerisation and related reactions of mononuclear tungsten carbyne complexes. Crystal structures of the compounds [W{C(H)(C6H4Me-4)}(I)(CO)2(η-C5H5)] and [W{η2-C2(OH)(C6H4Me-4)}(CO)(PMe3)(η-C5H5)] [BF4]· (Me2CO)

Protonation of the compounds [W( 6;CR)(CO) 2 (η-C 5 H 5 )] R = C 6 H 4 Me-4 or Me) with ca. 0.5 mol equivalents of the reagent HBF 4 ·Et 2 O affords the ditungsten salts [W 2 (η-H)(η-RC 2 R)(CO) 4 (η-C 5 H 5 ) 2 ] [BF 4 ] formed via a coupling of the carbyne groups in the precursors. These compounds are readily deprotonated to give the bridged alkyne complexes [W 2 (η-RC 2 R)(CO) 4 (η-C 5 H 5 ) 2 ], a process which is reversed with acid. Aqueous HI with [W( CR)(CO) 2 (η-C 5 H 5 )] affords the iodo carbene complexes [W( CHR)(I)(CO) 2 (η-C 5 H 5 )]. The structure of the species with R = C 6 H 4 Me-4 has been established by X-ray diffraction [W C 2.05(2)A]. The tolyl substituent on the alkylidene carbon atom is transoid to the ηC 5 H 5 ligand, and the alkylidene group is transoid to the iodine atom. Protonation of the ketenyl-tungsten complexes (R = C 6 H 4 Me-4, PR′ 3 = PMe 3 , PPr 3 i or PMePh 2 ; R = Me, PR′ 3 = PMe 3 ) affords the salts [W{η 2 C 2 (OH)(R)}(CO)(PR′ 3 )(η-C 5 H 5 )][BF 4 ] containing hydroxy-alkyne ligands. The structure of the species with R = C 6 H 4 Me-4 and PR′ 3 - PMe 3 has been established by X-ray diffraction. It contains an acetone molecule of crystallisation which is hydrogen bonded to the proton of the hydroxyl group on the alkyne. The 1 H and 13 C-{ 1 H} NMR spectra of the new compounds are reported and discussed.

The reaction of molybdenum and tungsten carbyne complexes with sulphur and selenium; crystal structures of [Mo{η2-(S2CCH2But)}-(CO)2(η-C5H5)] and [W{η2-(S2CC6H4Me-4)}(CO)2(η-C5H5)]

Reaction of [M(CR)L2(η-C5H5)][M = Mo, R = CH2But, L = P(OMe)3 or CO; M = W, R = C6H4Me-4, L = CO] with sulphur affords the complexes [M{η2-(S2CR)}L2(η-C5H5)]. Similar reactions between [Mo(CCH2But)(CO)2(η-C5H5)] or [W(CC6H4Me-4)(CO)2(η-C5H5)] and selenium give the related complexes [M{η2-(Se2CR)}(CO)2(η-C5H5)](M = Mo, R = CH2But; M = W, R = C6H4Me-4). X-Ray diffraction studies on the isostructural products obtained from sulphur and the molybdenum or tungsten carbonyl carbyne complexes show that a M(CO)2(η-C5H5)(M = Mo or W) moiety is bonded to a thioacetate ligand forming a planar MS2C ring of dimensions M–S 2.47, C–S 1.68 A, S–M–S 68, and S–C–S 110 °. The metal atom can be regarded as seven-co-ordinate with the cyclopentadienyl group occupying three co-ordination sites. Both structures are monoclinic, space group P21/c; the molybdenum compound has been refined to R 0.033 for 2 165 reflections and the tungsten compound to R 0.042 for 2 382 reflections. The mechanism of formation of these complexes is discussed in terms of initial electrophilic attack on the carbyne carbon.

Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 25. Protonations of tolylmethylidyne ligands bridging tungsten–chromium, –cobalt, and –platinum bonds and the X-ray crystal structure of [PtW{µ-σ:η3-CH(C6H4Me-4)}(CO)2(PMe3)2(η-C5H5)][BF4]

The Complex [Cr(thf)(CO)(NO)(η-C5H5)](thf = tetrahydrofuran), generated in situ from [Cr(CO)2(NO)(η-C5H5)] by u.v. irradiation, reacts with [W(CC6H4Me-4)(CO)2(η-C5H5)] to afford the dimetal compound [CrW(µ-CC6H4Me-4)(CO)3(NO)(η-C5H5)2]. Protonation of the latter, and the complexes [CoW(µ-CC6H4Me-4)(CO)3(η-C5H5)(η-C5Me5)] and [PtW(µ-CC6H4Me-4)(CO)2(PR3)2(η-C5H5)](PR3= PMe3, PMe2Ph, or PMePh2), with HBF4·Et2O affords the salts [MW{µ-σ:η3-CH(C6H4Me-4)}(CO)2(Ln)(η-C5H5)][BF4][MLn= Cr(CO)(NO)(η-C5H5), Co(CO)(η-C5Me5), or Pt(PR3)2]. N.m.r. data (1H, 13C-{1H}, 13P-{1H}, and 195Pt-{1H}) for the new compounds are reported and discussed. A single-crystal X-ray diffraction study was made on the compound [PtW{µ-σ:η3-CH-(C6H4Me-4)}(CO)2(PMe3)2(η-C5H5)][BF4]. In this salt the Pt–W bond [2.795(1)A] is bridged by the CH(C6H4Me-4) group in such a manner that two carbons of the aryl ring form an η2 attachment to the tungsten so that the µσCH(C6H4Me-4) group as a whole adopts an η3-bonding mode to the tungsten and a to the platinum [W–C 2.166(14), 2.406(14), and 2.602(13)A; Pt–µ-C 2.053(14)A]. The tungsten atom carries a cyclopentadienyl ligand and a terminally bound CO group, while the remaining carbonyl semi-bridges the metal–metal bond [W–C–O 155.1 (14)°]. The platinum atom is in an essentially planar environment, ligated by the two PMe3 groups, the tungsten atom, and the bridging carbon atom. Crystals are monoclinic (space group P21/c); the structure has been refined to R 0.054 for 3 430 reflections measured to 2θ= 50° at room temperature.

Stepwise synthesis of tungsten–platinum or –gold bonds bridged by alkylidyne ligands: X-ray crystal structures of [Pt3W2(µ3-CR)2(CO)4-(η-C5H5)2(cod)2](cod cyclo-octa-1,5-diene), [Pt2W3(µ-CR)2(µ3-CR)(CO)6(η-C5H5)3], and [AuW2(µ-CR)2(CO)4(η-C5H5)2][PF6]

The synthesis of metal complexes with bonds between tungsten and platinum or gold, bridged by tolylidyne ligands, is described; and the molecular structures of the species [Pt3W2(µ3-CR)2(CO)4(η-C5H5)2(cod)2](cod = cyclo-octa-1,5-diene), [Pt2W3(µ-CR)2(µ3-CR)(CO)6(η-C5H5)3], and [AuW2(µ-CR)2(CO)4(η-C5H5)2][PF6](R = C6H4Me-4) have been established by X-ray crystallography.

Proton-induced dimerisation and related reactions of mononuclear tungsten carbyne complexes

Abstract The products obtained by treating the compounds [W(CR)(CO) 2 (η-C 5 H 5 )] (R  C 6 H 4 Me-4 or Me) with HBF 4 ·Et 2 O or with HI are described and compared with species obtained by protonating or methylating the complexes [W{η 2 -C(R)C(O)}(CO)(PMe 3 )(η-C 5 H 5 )].

Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 12. Reaction of the complexes [PtW(µ-CC6H4Me-4)(CO)2(PR3)2(η-C5H5)] with carbon monoxide. Crystal structure of [Pt2W(µ3-CC6H4Me-4)(CO)4(PMePh2)2(η-C5H5)]

Di- and tri-metal complexes [PtW(µ-CR)(CO)3(PR′3)(η-C5H5)](R = C6H4Me-4; PR′3= PMe3, PMe2Ph, or PPh3) and [Pt2W(µ3-CR)(CO)4(PR′3)2(η-C5H5)](PR′3= PMe3, PMe2Ph, PMePh2, PPh3, or PEt3) have been isolated by treating toluene solutions of the compounds [PtW(µ-CR)(CO)2(PR′3)2(η-C5H5)] with CO gas at 1 bar and room temperature. N.m.r. data (1H, 13C-{1H},31P-{1H}, and l95Pt-{1H}) for the new compounds are reported and a single-crystal X-ray diffraction study has been carried out on the complex [Pt2W(µ3-CR)(CO)4(PMePh2)2(η-C5H5)]. The crystals are monoclinic, space group P21/c(no. 14), Z= 4, in a unit cell with a= 14.932 (13), b= 11.438(11), c= 26.394(24)A, β= 97.42(7)°. Poor crystal quality resulted in refinement to R 0.075 (R′ O.080) for 2 488 reflections to 2θ⩽ 40° collected at ambient temperature. The study established that the molecular structure is based on a Pt2W metal triangle, having a long Pt ⋯ Pt distance [2.989(3)A], and capped by a CC6H4Me-4 group with the ligated carbon atom equidistant from all three metals. The terminal phosphine and carbonyl ligands on each Pt atom are unsymmetrically transoid with respect to the Pt ⋯ Pt vector, and the two carbonyl ligands on the W atom are semi-bridging to the Pt atoms, again unsymmetrically. The molecule possesses no symmetry. The nature of the Pt ⋯ Pt interaction, and the relationship between the complexes [Pt2W(µ3-CR)(CO)4(PR′3)2(η-C5H5)] and previously reported di- and tri-platinum complexes with bridging alkyne ligands, are discussed.

Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 21. Reactivity of µ-(methoxy-p-tolylmethylene) and µ-(p-tolylmethylidyne) groups at a platinum–tungsten centre. X-Ray crystal structure of [PtW{µ-C(OMe)C6H4Me-4}(µ-Ph2PCH2PPh2)(CO)5]

Treatment of [PtW{µ-C(OMe)R}(CO)5(cod)](R = C6H4Me-4, cod = cyclo-octa-1,5-diene) with dppm (Ph2PCH2PPh2) affords [PtW{µ-C(OMe)R}(µ-dppm)(CO)5](1), the structure of which has been established by X-Ray crystallography. As expected, the platinum–tungsten bond [2.818(3)A] is spanned by the dppm and C(OMe)R ligands. The five-membered ring involving the chelating phosphine and the two metal atoms adopts an envelope conformation with one of the P atoms lying out of the plane. The [graphic omitted] ring is asymmetric [Pt–C 1.97(3), W–C 2.49(3)A]. The platinum atom carries one terminal carbonyl ligand and the tungsten atom four, making the co-ordination at these two metal centres essentially square planar and octahedral, respectively. Compound (1) reacts with HBF4·OEt2 to yield the salt [PtW(µ-CR)(µ-dppm)(CO)5][BF4], and with BBr3 to give [PtWBr(µ-CR)(µ-dppm)(CO)4], but the latter is better prepared by treating the salt with NEt4Br. Reactions of the complex [PtW(µ-CR)(µ-dppm)(CO)5][BF4] with several nucleophilic reagents have been investigated leading to the synthesis of the compounds [PtW(µ-CRR′)(µ-dppm)(CO)5](R′= Me, H, CCBu1, or SC6H4Me-4) and [PtW{µ-C(η2-C5H5)R}(µ-dppm)(CO)4]. The n.m.r. data (1H, 31P-{1H}, 13C-{1H}, and 195Pt-{1H}) for the new compounds are reported and discussed.

Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 11. Some reactions of the compound [PtW{µ-C(OMe)C6H4Me-4}(CO)5(η-C8H12)] and the crystal structure of one isomer of [Pt3{µ-C(OMe)C6H4Me-4}3(CO)3]

The compound [(OC)5[graphic omitted]t(cod)](cod = cyclo-octa-1,5-diene) reacts with PMe3, dppe (Ph2PCH2CH2PPh2), and pdma [C6H4(AsMe2)2–1,2] to give the bis-phosphine complexes [(OC)5[graphic omitted]tL2][L2=(PMe3)2, dppe, or pdma] in which the dimetallacyclopropane rings are preserved. In contrast, reactions with CO or CNBut afford triplatinum compounds [Pt3{µ-C(OMe)C6H4Me-4}3L3](L = CO or CNBut)(two isomers). For L = CO the isomers were separated, and a single-crystal X-ray diffraction study was carried out on one species thereby establishing its configuration. The crystals are orthorhombic, space group P212121, Z= 4, in a unit cell with lattice parameters a= 11.085(2), b= 15.554(3), and c= 18.733(5)A. The structure has been refined to R 0.046 (R′ 0.045) for 2 699 reflections to 2θ⩽ 50°[Mo-KαX-radiation] collected at room temperature. The molecule consists of an essentially equilateral triangle of platinum atoms [mean Pt–Pt 2.624(1)A], each metal atom carrying a terminally bonded CO ligand [mean Pt–CO 1.82(3)A]. The three metal–metal vectors are bridged by C(OMe)C6H4Me ligands [mean Pt–µ-C 2.15(3)A], such that the plane defined by the metal atoms and the three ligated carbon atoms is perpendicular to the planes of these µ-C atoms and the O and C atoms to which they are bonded. Moreover, two of these groups have the same orientation with respect to the Pt3 plane whilst the third is inverted. The 195Pt n.m.r. spectrum of this ‘ asymmetric ’ isomer has been measured and analysed. Spectroscopic data for all the new compounds are given.

Methylene group transfer to carbon–metal multiple bonds: crystal structures of [TiW{µ-C(C6H4Me-4)CH2}(µ-CO)(CO)(η-C5H5)3] and [PtW{µ-C(C6H4Me-4)CH2}(CO)2(PMe3)2(η-C5H5)]

In toluene–tetrahydrofuran, the reagent [(η-C5H5)2[graphic omitted]H2] reacts with [W(CR)(CO)2(η-C5H5)] or [TiW(µ-CR)(µ-CO)(CO)(η-C5H5)3](R = C6H4Me-4) to give [TiW(µ-CRCH2)(µ-CO)(CO)(η-C5H5)3], and with [PtW(µ-CR)(CO)2(PMe3)2(η-C5H5)] to yield [PtW(µ-CRCH2)(CO)2(PMe3)2(η-C5H5)]; the latter and [TiW(µ-CRCH2)(µ-CO)(CO)(η-C5H5)3] have been structurally characterised by X-ray diffraction.