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The molecular structure of trans-[PtCl(CCPh)(PEt2Ph)2] has been determined by X-ray diffraction methods. The crystals are monoclinic, space group P21, with a= 12.359(3), b= 13.015(3), c= 9.031(2)A, β= 101.65(2)°, and Z= 2. The structure has been solved by the heavy-atom method and refined by full-matrix least squares to R 0.046 for 1 877 diffractometric intensity data. The crystals contain discrete molecules in which the platinum coordination is square planar. The phenylethynyl group is non-linear, with a Pt–CC angle of 163(2)°. Selected bond lengths are Pt–Cl 2.407(5) and Pt–C 1.98(2)A. The structural trans influences of CCPh, CHCH2, and CH2SiMe3 ligands in platinum(II) complexes are compared; there is only a small dependence on hybridization at the ligating carbon atom.

Reactions of [Me 2 Pt(μ-dmpm) 2 PtMe 2 ], (dmpm = Me 2 PCH 2 PMe 2 ) with halogens, (X 2 ) or methyl iodide give the platinum(IV)-platinum(II) complexes [Me 3 Pt(μ-X)(μ-dmpm) 2 PtMe]X or [Me 3 IPt(μ-dmpm) 2 PtMe 2 ] respectively, and the former reactions involve methyl group transfer between the platinum atoms of the binuclear complex; one of the derivatives ([Me 3 Pt(μ-I)(μ-dmpm) 2 PtL]I 3 , L = 1/2I + 1/2 Me) is characterized by an X-ray crystal structure determination.

Reactions of [Fe(SR′)(CO)2(η5-C5H5)] with activated alkynes CF3CCCF3 and MeO2CCCCO2Me give heterocyclic complexes [[graphic omitted]R′}(CO)(η5-C5H5)](R′= alkyl or aryl, R = CF3 or CO2Me). Related derivatives [[graphic omitted]R′}(CO)2(η5-C5H5)](R′= Me or Et) obtained from [W(SR′)(CO)3(η5-C5H5)] and the alkynes in hexane at 20 °C undergo a sequence of thermal isomerisations above 25 °C involving initially a novel 1,3 shift of the SR′ ligand across the eneone ligand to give the η2-vinyl complex [W{η2-C(R)C(R)C(O)SR′}(CO)2(η5-C5H5)](R = CF3 only) followed by S-bonded vinyl ketone complexes [[graphic omitted]R′}(CO)2(η5-C5H5)] and ultimately O-bonded vinyl ketone derivatives [[graphic omitted]}(CO)2(η5-C5H5)] and co-ordinatively unsaturated alkyne complexes [W(SR′)(CO)(RCCR)(η5-C5H5)](R = CF3 only). An X-ray structure determination of the η2-vinyl complex [W{η2-C(CF3)C(CF3)C(O)SMe}(CO)2(η5-C5H5)] reveals the first example of a vinyl group bonded to a metal via both carbon atoms and therefore acting as a three-electron donor ligand. The structure consists of an approximately octahedrally co-ordinated tungsten atom bonded to an η5-C5H5 ligand which occupies one face of the octahedron. Two carbonyl ligands occupy two octahedral sites while the third is occupied by the η2-C(CF3)C(CF3)C(O)SMe ligand which adopts an orientation such that the vinylic C–C axis lies approximately parallel to one of the W–CO axes.

The compounds [M(C 6 H 4 NNPh)(η 5 -C 5 H 5 )] (M = Ni, 1a ; M = Pd, 1b ; M = Pt, 1c ) display the unexpected reactivity pattern Pd > Pt > Ni on treatment with monotertiary phosphines. Their structures, determined by X-ray diffraction, provide no help in explaining this reactivity pattern but do illustrate the effects of differing metal size and polarisability. In particular, 1b and 1c display highly distorted M-η 5 -C 5 H 5 geometries: MC(η 5 -C 5 H 5 ) distances range from 2.167(3) to 2.408(3) A for 1b and 2.153(7)-2.367(8) A for 1c . The NiC(η 5 -C 5 H 5 ) distances in 1a are more regular: 2.036(5)-2.148(5) A. 1a is monoclinic, space group P 2 1 / n , with a 9.502(1), b 16.155(2), c 18.659(3) A, β 99.16(1)°, Z = 8, R = 0.037 for refinement of 361 parameters using 3072 unique intensities. 1b is monoclinic, space group P 2 1 / a , a 7.046(1), b 14.897(2), c 13.709(2) A, β 101.66(1)°, Z =4, R 0.022 for refinement of 237 parameters from 3099 unique intensities. 1c is isomorphous and isostructural with 1b , a 6.993(2), b 14.846(3), c 13.709(4) A, β 101.92(2) °. R = 0.027 for refinement of 181 parameters from 2818 unique intensities.

Reactions of the η2-vinyl complex [W {η3-C(CF3)C(CF3)SPri}(CF3CCCF3)(η5C5H5)] with isocyanides RNC give metallacyclopentadiene derivatives [ WC(CF 3 )C(CF 3 )C(CF 3 )C (CF3)(SPri)(CNR)2 (η5-C5H5)] (R = Me, Ph or 4-MeC6H4) via coordinatively unsaturated intermediates [ WC(CF 3 )C(CF 3 )C(CF 3 )C (CF3)(SPri)(CNR)(η5-C5H5)] isolated and characterised in the case R = 4-MeC6H4. The crystal structure of the d2 complex [ WC(CF 3 )C(CF 3 )C(CF 3 )C (CF3)(SPri)-4-MeC6H4NC)2(η5-C5H5)] has been determined by X-ray methods. The WC4(CF3)4 ring system is approximately planar, with single WC bonds, mean length 2.210(4) A, and localised CC double bonds.

Triphenylphosphine and trimethylphosphite react with [(C5H5)(OC)2M(μ-SMe)M′(CO)5] (M, M′ = Mo, W) (II) to give [(C5H5)(OC)2)LM(μ-SMe)M′(CO)5] which on heating revert to II. On prolonged heating [(C5H5)(OC)2Mo(μ-SMe)W(CO)4}P(OMe)3}] is formed. [(C5H5)(OC)3W(μ-SMe)W(CO)5] reacts with I2 to give [(C5H5)(OC)2W(μ-SMe)(μ-I)W(CO)3I] for which the crystal structure has been determined.

Syntheses of the phospha-alkene complexes cis - and trans -[PtCl 2 (PEt 3 )(mesityl)P=CPh 2 ], and cis - [PtX 2 {(Mesityl)P=CPh 2 } 2 ](X=Cl, I, Me) complexes are reported. 31 P NMR spectra indicate that bonding of the phospha-alkene to the metal is via the phosphorus lone pair and this is confirmed by a single crystal X-ray diffraction study of cis -[PtCl 2 (PEt 3 ){(mesityl)P=CPh 2 }]CHCl 3 .

The 1J(PtP) coupling constants in the complexes cis-PtCl2 (R2PCH2 - CH2 PPh2), where R = CF3, C6 F5, and the bond lengths in the complex with R = CF3 indicate that the metalligand bonding is strongly influenced by the substituents on phosphorus.

A series of electroneutral alkoxy(organo)carbene complexes of platinum(II), cis-[PtX2L{C(OR′)(CH2R)}], has been prepared by reaction of the halide-bridged dimer [Pt2X4L2](X = Cl, Br, or l; L = PMe2Ph or PEt3) with monosubstituted acetylenes RCCH(R = Ph, Me, or Et) and alcohols R′OH (R′= Me, Et, or Prn). The complexes have been characterised analytically, by 1H and 31P n.m.r. and i.r. spectroscopy, and by X-ray analysis of a typical member of the series. Crystals of the title complex are monoclinic, space group P21/n, with a= 15.084(2), b= 8.4,19(3), c= 15.801(3)A, β= 92.93(2)°, and Z= 4. The structure has been solved by the heavy-atom method and refined by full-matrix least squares to R= 0.036 for 2 166 diffractometric intensity data corrected for absorption. The crystals are built of discrete molecules with cis square-planar geometry. Selected bond lengths are : Pt–P 2.240(3), Pt–Cl(trans to P) 2.355(3), Pt–Cl(trans to C) 2.375(3), and Pt–C 1.920(9)A. The molecular structure displays a Pt ⋯ H contact of 2.6(1)A to a hydrogen atom of the ethoxy CH2 group. The 1H n.m.r. spectra indicate that this Pt ⋯ H interaction persists in solution, and is a general feature of these neutral complexes.

Reaction of [(CO) 3 Co(μ-CF 3 C 2 CF 3 )Co(CO) 3 ] with [{(C 5 H 5 )Fe(CO) 2 } 2 ] leads to the new heterometallic clusters [(C 5 H 5 ) 2 Fe 2 Co 2 (μ 3 -CO) 2 (CO) 4 (μ-CF 3 C 2 CF 3 )] ( 1 ), [(C 5 H 5 ) 3 Fe 3 Co(μ 3 -CO) 2 (CO) 2 (μ-CF 3 C 2 CF 3 )] ( 2 ) and product 3 . Complex 3 is also obtained upon thermolysis of 1 . Spectroscopic studies and single crystal X-ray analysis establish that 3 is the bis-carbyne complex [(C 5 H 5 ) 2 Fe 2 Co 2 (μ-CO)(CO) 4 {μ 3 -C(CF 3 )} 2 ], and is therefore derived by cleavage of the CC bond of the alkyne.

The crystal structure of chlorobis(π-cyclopentadienyl)(triphenylsilyl)zirconium(IV) has been determined by X-ray diffraction methods. A monoclinic unit cell of dimensions a= 10·071(4), b= 17·331(7), c= 16·329(7)A, and β= 121·57(3)°, contains four monomeric (π-C5H5)2ZrCl(SiPh3) molecules. The space group is P21/c. The structure has been refined by least-squares methods to a conventional R of 0·058, based on 2488 intensities measured on an automatic four-circle diffractometer. The co-ordination about the silicon atom is approximately tetrahedral; the co-ordination about the zirconium atom is also roughly tetrahedral, if the cyclopentadienyl ligands are regarded as unidentate. The Zr–Cl distance is 2·430(3)A. The Zr–Si bond is unexpectedly long; its length, not previously determined, is 2·813(2)A.

The results of precise X-ray studies of the fumaronitrile complex of hydridocarbonylbis(triphenylphosphine)iridium and of the tetracyanoethylene complex of bromocarbonylbis(triphenylphosphine) iridium are presented and detailed comparisons are made with the results on other simple olefin-metal structures available in the literature.

The structure crystal of the title compound has been determined from X-ray diffractometer data. The crystals are monoclinic, a= 9·936(4), b= 11·825(7), c= 13·088(4)A, β= 101·75(3)°, Z= 4, space-group P21/c. The structure was solved by the heavy-atom method and refined by full-matrix least-squares to R 0·046 for 1644 independent reflexions. The arrangement of molecular units in the crystal structure is such that there is a Pt⋯Pt contact of 3·48 A between centrosymmetrically related molecules. Co-ordination around the platinum atom is square planar. The mean Pt–C bond length [1·896(16)A] suggests that there is appreciable metal-ligand back-donation. Pt–Cl (mean) is 2·308(5)A.

The structure of the complex hydridocarbonyl(fumaronitrile)bis(triphenylphosphine)iridium, IrH(CO)( trans -NCCHCHCN)[P(C 6 H 5 ) 3 ] 2 , has been determined from a single crystal X-ray analysis. The complex crystallizes in a monoclinic cell of dimensions a = 21.289(14), b = 9.383(3), c = 21.650(10) A, β= 123.87(2)°. The observed density is 1.53 g·cm −3 , whereas the density calculated for four formula units per unit cell is 1.524 g·cm -3 . On the basis of a successful structure analysis, the space group is C 2/ c . The structure has been refined by least-squares methods to a conventional R -factor of 0.056 for the 2274 independent reflections whose intensities were above background, when measured by counter techniques. The molecules are monomeric; the configuration around the iridium atom is trigonal bipyramidal, with the olefin and phosphine ligands in the equatorial plane, which also contains a twofold axis of crystallographic symmetry. The fumaronitrile ligand is nonplanar, the dihedral angle between the two planes which contain a carbon atom of a cyanide group and both olefinic carbon atoms is 136(2)°. The IrP and IrC distances are respectively 2.317(3) and 2.110(9) A, while the CC distance is 1.431 (20) A. Assuming an IrH bonded distance of 1.6 A, the nonbonded contact between the hydridic hydrogen atom and an olefin carbon atom is 2.6 A. It is of interest that the hydridic hydrogen atom is cis to the olefin since complexes related to the present one are believed to play a role in the catalyzed hydrogenation reactions of olefins.

The molecular geometry of the title compound has been determined by X-ray crystal-structure analysis from diffractometer data. The crystals are monoclinic, space-group P21/c, a= 12·238(6), b= 14·818(10), c= 21·687(10)A, β= 121·28(3)°, Z= 4. The structure was solved by the heavy-atom method and refined by full-matrix least-squares to R 0·081 for 2283 reflections.The crystals are built of monomeric molecular units, with distorted octahedral co-ordination around the molybdenum atom. The molybdenum–ligand bond distances are: Mo–O 1·801(9), Mo–Cl (trans to O) 2·424(4), Mo–Cl (trans to P) 2·482(4), Mo–P (trans to Cl) 2·522(4), and Mo–P (trans to P) 2·580(5) and 2·553(5)A.

Thermolysis of the η2-vinyl complex [W{η3-C(CF3)C(CF3)SBut}(CF3CCCF3)(η5-C5H5)] gives the η3-ethenethiolato derivative (E)-exo-[W{η3-SC(CF3)C(CF3)H}(CF3CCCF3)(η5-C5H5)], which undergoes concomitant exo→endo and E→Z isomerisation to give (Z)-endo-[W{η3-SC(CF3)C(CF3)H}(CF3CCCF3)(η5-C5H5)], thus providing evidence for a ring-flip mechanism in metal-promoted alkene isomerisations.

The complex [Pt 2 Me 2 (μ-H)(μ-dppm) 2 ][PF 6 ] (I, dppm = Ph 2 PCH 2 PPh 2 ) has been prepared and characterised by 1 H and 31 P NMR spectroscopy and by a full molecular structure determination by X-ray methods. The complex undergoes only slow reductive elimination of methane induced by added tertiary phosphine at 70°C.

1 H and 31 P NMR parameters for cis -[PtX 2 L 2 ] and [PtXL 3 ] + complexes in which L is PC 6 F 5 (CH 3 ) 2 and X = a range of anionic ligands, together with crystal structure analyses of cis -[PtX 2 L 2 ], (I, X = Cl; II, X = CF 3 ) and [Pt(CH 3 )L 3 ] [PF 6 ] (III), suggest that electron-withdrawal by C 6 F 5 has only a limited effect on the metalligand bonding and that the trans -influences of CH - 3 and CF - 3 on PtP bonds are of similar magnitude. The dependence of 19 F NMR chemical shifts and coupling constants on the nature of the PxX bonding is also described.

Reactions of Tl (LL)(LL–= pyridine-2-thiolato), pyrimidine-2-thiolato, or thiazoline-2-thiolato) with the bis-hexafluorobut-2-yne complexes [MCl(CF3CCCF3)2-(η-C5H5)](M = Mo or W), give products [M {(LL)-C(CF3)·C(CF3)}(CF3CCCF3)(η-C5H5] containing a novel η2-vinyl ligand resulting from nucleophilic attack of LL–on an alkyne ligand whereas with [WCl(CF3CCCF3)2-(η-C5H5)] the thallium(I) salt of 2-mercaptopyridine N-oxide unexpectedly promotes cyclopentadienyl group displacement to give the co-ordinatively unsaturated bis-hexafluorbut-2-yne complexes [W(SC5H4NO)2(CF3CCCF3)2]; and [W(SC5H4NO)(CF3CCCF3)2]; the structure of [Mo{SC5H4NC(CF3)·C(CF3)}(CF3CCCF3)(η-C5H5)] has been determined by X-ray crystallography.

Novel complexes containing Pt3(µ3-SnX3) groups have been prepared by reaction of [Pt3(µ3-CO)(µ-dppm)3][PF6]2(dpmm = Ph2PCH2PPh2) with organotin hydrides or with SnX3– and are of intrest as possible models for heterogeneous Pt–Sn/support catalysts; the structures of [Pt3{µ3-SnMe2(PO2F2)}(µ-dppm)3]+ and disordered {[Pt3(µ3-SnF3)(µ3-CO)(µ-dppm)3][PF6]}0.75[Pt3(µ3-SnF3)(µ3-Cl)(µ-dppm)3]0.25 are determined, the latter being the first SnF3– complex to be crystallographically characterized.

Thiolato complexes [W(SR)(CF3C2CF3)2(η5-C5H5)] have been shown to exhibit two basic structures, a bis-alkyne form [W(SR)(CF3CCCF3)2(η5-C5H5)](R = C6F5, Ph, or 4-MeC6H4) and an η2-vinyl form [[graphic omitted]R(CF3CCCF3)-(η5-C5H5)](R = Me, Et, Pri, Prn, PhCH2, or But) shown by X-ray diffraction studies of the isopropyl complex to result from nucleophilic attack of the SR ligand on an acetylenic carbon atom.

The X-ray crystal structure analysis of cis-[PtPh2(Ph2PCH2PPh2)] suggests that the unusually low PtP coupling constant is a consequence of distortion of the valency angles at the platinum and phosphorus atoms; the restrictive geometry of the chelate ring does not effect the lengths of the metal—ligand bonds.

Reaction of t-butyl isocyanide with the two co-ordinated alkynes in [MSR′(CF3CCCF3)2(η5-C5H5)](M = Mo, R′= C6F5; M = W, R′=p-tolyl) has been shown to involve initial attack at the alkyne followed by transfer of CNBut to the metal with concomitant oxidative metallocyclisation and subsequent reductive cyclisation to give [MSR′(CNBut){η2-C4(CF3)4CNBut}(η5-C5H5)] shown by X-ray diffraction studies (M = W, R′= Pri) to contain a tetrakis(trifluoromethyl)cyclopentadienimine ligand attached only via the C–N bond to the metal.

Up to three methylene groups from diazomethane may be incorporated into hydridodiplatinum(I) complexes by insertion into Pt–Pt. Pt–H and, in one case, a Pt–P bond; X-ray structure determination establishes the an M2(µ-CH2) group with no M–M bond are reported.

Addition of alkynes to isomeric η2-C,C-vinyl [M{η3-C(CF3)C(CF3)SR′}(CF3CCCF3)(η5-C5H5)](M = Mo, W; R′= Pri) and bis-alkyne complexes [MSR′(CF3CCCF3)2(η5- C5H5)](M = W, R′= 4-MeC6H4) gives new metallacycles formed by linking of two or three alkynes; X-ray analyses reveal two modes of bonding for the tris alkyne (CR)6 ligands.

Bond lengths in electroneutral, monomeric chloroplatinum(II) complexes containing carbon-donor ligands indicate that there is a correlation between the extent of platinumcarbon multiple bonding and the length of the PtCl (trans to C) bond. A qualitative model is suggested to account for the trans-influence of both σ-donor and π-acceptor ligands on PtCl bonds.

TheX-ray analysis of the title compound was based on 4 198 diffractometric intensity data, corrected for absorption, Crystals are triclinic. space group P, a= 10.4822(9), b= 9.5929(7), c= 11.0065(8)A. α= 97.57(1). β= 117.96(1), γ= 93.80(1)°. Z= 2. The structure was solved by the heavy-atom method and refined by full-matrix least-squares to R 0.037.The crystals are built of discrete monomeric molecules with cis-square-planar geometry. The Pt–C [1.858(7)A] and Pt–Cl(trans to C)[2.276(1)A] distances indicate that the carbonyl ligand possesses π-acceptor properties and exerts an extremely small trans-influence on the Pt–Cl bond. The Pt–P [2.282(2)A] and Pt–Cl(trans to P)[2.343(2)A] bond lengths may reflect a weak cis-influence of the carbonyl group.

MoOCl4 in the solid state has a square pyramidal structure with chlorine-bridging trans to the oxygen linking the molecules into infinite chains. The structure gives holes in the lattice occupied by solvate molecules.

The reaction of [Pt2H2(µ-H)(µ-dppm)2][PF6][dppm = bis(diphenylphosphino)methane] with dppm proceeds by reductive elimination of H2 to give [Pt2H-(dppm)(µ-dppm)2][PF6], which has been shown by single-crystal X-ray crystallography to contain both bridging and terminal dppm ligands and a Pt–Pt bond [2·770(2)A] and which undergoes reversible oxidative addition of RSH (R = Me or PhCH2) at the platinum(I) centres.

The binuclear complex [Pt2H2(µ-dppm)2][PF6], dppm = Ph2PCH2PPh2, is an active catalyst precursor for the water gas shift reaction, especially at low pressures of carbon monoxide; the catalytic solutions are shown to contain cluster complexes such as the tetranuclear [Pt4(µ-CO)2(µ-dppm)3{Ph2PCH2P(:O)Ph2}], whose ‘butterfly’ structure has been determined by X-ray crystallography.

The migration of an alkylthio group across an enone ligand co-ordinated to tungsten has been demonstrated; X-ray diffraction studies have established the structures of the two isomeric products, one of which contains a novel alkyl-carbene ligand which functions as a three-electron donor to the metal.

Nucleophilic atteck of phosphines, phosphites, and t-butyl isocyanide (L) on the bis-hexafluorobut-2-yne complexes [WBr2CO(CF3CCCF3)2] and [MX(CF3CCCF3)2(η-C5H5)](M = Mo, W; X = Cl, SC6F5: M = W; X = SC6H6Me-p) occurs at an acetylenic carbon atom to give 1:1 adducts shown by X-ray deffraction studies to contain a metal-stabilised 1–3 dipolar vinyl ligand LC(CF3)·C(CF3) co-ordinated in an η2 manner to the metal centre.

Reaction of chlorine with cis -[PtCl 2 {C(NHR)(NHR′) }PEt 3 ] and trans -[PtCl{C(NHR)(NHR′)}(PEt 3 ) 2 ]ClO 4 gives analogous platinum(IV) carbene complexes when R = R′ = Me; but when R = Me or Et and R′ = Ph, 2-metallation and 4-chlorine substitution of the phenyl group occurs, shown by the X-ray structure of [PtCl 2 {C(Cl·C 6 H 3 NH)(NHMe)}(PEt 3 ) 2 ]ClO 4 .

The molecular structure of the title complex has been determined by X-ray methods. The crystals are monoclinic, space group I2/a, with eight molecules in a unit cell of dimensions a= 26.122(3), b= 11.006(2), c= 29.775(3)A, and β= 106.34(1)°. The structure has been refined by least-squares methods to R= 0.042 for 4 855 diffractometric intensities. The complex contains a [graphic ommitted] metallocycle, obtained by insertion of platinum into a B–H bond of a diphenyl(ortho-carboranyl)phosphine. A distorted square plane around platinum is completed by the phosphorus atom of a second Ph2PC2B10H11 ligand and by a chlorine atom. Both ortho-carboranyl cages have approximately icosahedral geometries. Selected bond lengths are: Pt–Cl 2.415(3), Pt–B 2.073(9), Pt–P(chelate) 2.279(3), and Pt–P(non-chelate) 2.305(2)A.

X-ray structure determination of the title compound has shown that iodination of [Pt2Me4 (,u-Me2PCH2PMe2)2] involves an oxidative addition reaction accompanied by methyl group transfer between the two platinum atoms. The crystal structure is built of symmetrical, linear [Isl- anions and partially disordered cations, in which I- or CH3- ligands occupy the L sites with nearly equal propability. In the cations the Pt(II) and Pt(IV) centres are characterised by square planar and octahedral coordination geometries; they are locked into close proximity [Pt ... Pt 386.3(1) pm] by two bridging Me2PCH2PMe2 ligands. The L-shaped LPt(μ -I)PtMe fragment [Pt-I-Pt 91.2(1)0 ] is perpendicular to the Pt(l)P2L(μ -I) and Pt(2)P2C2 coordination planes. The overall geometry of the cation approximates to C8 symmetry. Crystals of the title compound are triclinic, space group Pl, with two formula units in a unit cell of dimensions a = 924.0(2), b = 932.8(4), c = 1804.4(7) pm, a = 102.39(4), fl = 94.63(3) and y = = 96.93(3)0 . Lecrst-squares refinement of the structural model defined by 221 parameters converged at a conventional R index on F of 0.049 for 5045 reflections with I ~ 3 a (I).