Terminal CO Ligands Research Articles

Lanthanide carbonyl complexes

In the cases of a typical lanthanide (Sm) and atypical lanthanide (Yb), they have shown that activated metallic Sm and Yb react with free CO (p/sub CO/ = 20 atm) at 20/sup 0/C in THF to give carbonyl complexes Ln(CO)/sub m/(THF)/sub n/ (Ln = Sm and Yb) (I). Two bands (1995 and 2020 cm/sup -1/) are found in the IR spectra of solutions of (I) in THF in the stretching band region for the terminal CO ligands. The position and relative intensity of these bands is virtually independent of the nature of the lanthanide (in contrast to the data obtained in a matrix (2)). Complexes (1) are stable in THF for several hours. An attempt to isolate (I) from solution by removal of THF leads to decomposition of the complex and formation of a lanthanide-containing powder insoluble in organic solvents having apparent polymeric structure. The presence of lanthanide was shown by x-ray fluorescence analysis. The IR spectra of these compounds have bands at 1747 and 1754 cm/sup -1/ which may be assigned to stretching vibrations of the bridge CO groups.

Structural studies on polynuclear osmium carbonyl hydrides: XXXII. Crystal and molecular structure of CpWOs 3(CO) 9(μ-H)(μ-O)[μ-CCH( p-tol)], a hydrido-vinylidene cluster complex produced by rearrangement of a μ 3-alkylidyne cluster

The hydrido-vinylidene complex CpWOs 3(CO) 9(μ-H)(μ-O)[μ-CCH( p-tol)], previously prepared by pyrolysis of CpWOs 3(CO) 9(μ-O)[μ 3-CCH 2( p-tol)] in boiling toluene, has been investigated crystallographically. The complex crystallizes in the centrosymmetric monoclinic space group P2 1]/ c (No. 14) with a 9.522(2), b 22.376(6), c 12.761(3) Å, β 98.276(17)°, V 2690.5(11) Å 3 and D calc'd 2.97 g/cm 3 for Z = 4 and molecular weight 1204.8. Single crystal X-ray diffraction data (Mo- K α, 2θ 4.0–40.0°) were collected with a Syntex P2 1 diffractometer and the structure refined to R 7.9% for all 2529 data [ R 5.6% for those 2041 reflections with | F o| > 3σ(| F o|)). The molecule is based upon a tetrahedral WOs 3 core. Each Os is linked to three terminal CO ligands and the W atom is bonded to an η 5-C 5H 5 ligand. The μ-vinylidene fragment spans the WOs(2) edge (WC(1) 2.082(40), Os(2)C(1) 2.148(39) Å) and the μ-oxo ligand spans the WOs(3) edge of the cluster (WO 1.791(23) and Os(3)O 2.131(21) Å). The hydride ligand (which was not directly located) is believed to span the elongated Os(3)Os(1) edge of the tetrahedron.

Reversible carbon—carbon bond formation by interconversion of CO and μ-acyl ligands on the face of an osmium cluster

Addition of PMe 2Ph to the μ-acyl complex ▪ (III) induces carbon—carbon bond cleavage with conversion of the μ-acyl group to a terminal CO ligand and gives the zwitterionic compound [(OC) 4 RePMe 2Ph] +[Os 3H(CO) 10{μ-CC(Ph)C CPh}] − (IV). Facile elimination of CO (or PMe 2Ph) from IV at the rhenium atom leads to the back formation of a μ-acyl group and gives the complex ▪ (V) or complex III.

Chemistry of di-and tri-metal complexes with bridging carbene or carbyne ligands. Part 38. Ruthenium–tungsten compounds: crystal structures of [RuW-(µ-Cl)(µ-CMe)(Cl)(CO)2(PPh3)2(η-C5H5)] and [RuW2(µ3-C2Me2)(CO)7(η-C5H5)2

Purple crystals of the compound [RuW(µ-Cl)(µ-CMe)(Cl)(CO)2(PPh3)2(η-C5H5)] are obtained by placing a diethyl ether solution of [W(CMe)(CO)2(η-C5H5)] above a tetrahydrofuran (thf) solution of [RuCl2(PPh3)3]. The ruthenium–tungsten complex has been characterised by an X-ray diffraction study. The Ru–W bond [2.769(1)A] is spanned by the Cl and CMe ligands [C–W 1.942(11), C–Ru 2.021(9), Ru–Cl 2.447(3), W–Cl 2.497(3)A]. In addition to the cyclopentadienyl ligand the W atom carries terminal Cl and CO ligands which exhibit a positional disorder between two effectively interchangeable sites in the complementary ratios 3: 1. The ruthenium atom is ligated by two PPh3 groups and a CO group. Treatment of the ruthenium–tungsten complex with MeCCMe affords [RuW(µ-Cl)(µ-CMe)(Cl)(CO)2(PPh3)(η-C2Me2)(η-C5H5)], possible structures for which are discussed on the basis of n.m.r. data. The compound [W(CMe)(CO)2(η-C5H5)] reacts with the species [Ru(CO)n(PPh3)5–n](n= 2 or 3) to afford an insoluble trimetal complex [RuW2(µ3-C2 Me2)(CO)6(PPh3)(η-C5H5)2]. The PPh3 group in the latter may be displaced with CO or PEt3 to give the species [RuW2(µ3-C2Me2)(CO)6(L)(η-C5H5)2](L = CO or PEt3), but the reaction with CO is reversed unless the PPh3 is removed by complexation. The structure of the heptacarbonyl complex has been established by X-ray diffraction. The molecule has a triangular metal core [Ru–W 3.026(1) and 2.835(1), W–W 2.944(1)A] bridged by the MeCCMe ligand in such a manner that the alkyne lies essentially parallel to one of the Ru–W vectors. Hence this ligand is σ bonded to the ruthenium atom and to one tungsten centre [C–RU 2.068(9), C–W 2.169(9)A] while being η2 co-cordinated to the other tungsten atom [C–W mean 2.281 (9)A]. The ruthenium atom carries three terminally bound CO ligands, while the tungsten atoms are each ligated by a C5H5 and two CO groups. Three of the four CO ligands bound to tungsten semi-bridge the edges of the metal–atom triangle. The complexes [RuW2(µ3-C2Me2)(CO)6(L)(η-C5H5)2] undergo dynamic behaviour in solution, as revealed by n.m.r. studies.

Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 15. Reactions of the complex [W(CR)(CO)2(η-C5H5)](R = C6H4Me-4) with iron carbonyls; crystal structures of [Fe2W(µ3-CR)(µ-CO)(CO)8(η-C5H5)] and [FeW2(µ3-RC2R)(CO)5L(η-C5H5)2](L = CO or O)

The compound [W(CR)(CO)2(η-C5H5)](R = C6H4Me-4) in diethyl ether at room temperature reacts with [Fe2(CO)9] to give the dimetal complex [FeW(µ-CR)(CO)6(η-C5H5)](1), and the two trimetal species [Fe2W(µ3-CR)(µ-CO)(CO)8(η-C5H5)](2) and [FeW2(µ3-RC2R)(CO)6(η-C5H5)2](3). Compound (2) with PMe2Ph or Ph2PCH2PPh2(dppm) affords [Fe2W(µ3-CR)(µ-CO)(CO)6L2(η-C5H5)][L = PMe2Ph (4), L2= dppm (5)], complexes in which the phosphine ligands are bonded to the two iron atoms. From the reaction between the complexes [Fe3(CO)12] and [W(CR)(CO)2(η-C5H5)], the trimetal compounds (2), (3), and [FeW2(O)(µ3-RC2R)(CO)5(η-C5H5)2](6) were isolated. Spectroscopic data (infrared and n.m.r.) for the new compounds are reported, and discussed in relation to their structures, which were firmly established for (2), (3), and (6) by single-crystal X-ray diffraction studies. Crystals of (2) are orthorhombic, space group P212121, Z= 4, in a unit cell with lattice parameters a= 10.078(8), b= 13.115(8), and c= 16.785(8)A. The structure was refined to R 0.030 (R′ 0.031) for 5 837 reflections having 2θ⩽ 60°(Mo–KαX-radiation) collected at 200 K. The molecule consists of a Fe2W triangle [Fe–W 2.805(2) and 2.756(2), Fe–Fe 2.538(2)A] capped by a triply bridging tolylidyne ligand [µ3-C–W 2.093(5), µ3-C–Fe 1.969(5) and 2.036(5)A]. The Fe–Fe bond is bridged by a CO group, the remaining carbonyl ligands being terminally bonded, two to the tungsten and three to each iron. Crystals of (3) are triclinic, space group P, Z= 2, in a unit cell with a= 8.622(2), b= 12.799(4), c= 13.443(8)A, α= 90.72(4), β= 108.45(4), and γ= 93.34(2)°. The structure has been refined to R 0.037 (R′ 0.039) for 4 337 reflections having 2θ⩽ 50° collected at room temperature. The molecule consists of a FeW2 triangle, the W–W distance [2.747(1)A] suggesting double bonding. The Fe–W separations [2.731(1) and 2.745(1)] are perceptibly different, and the shorter is transversely bridged by a RC2R alkyne group; one of the carbon atoms of the alkyne triply bridges the metal triangle [µ3-C–W 2.289(5) and 2.264(7), µ3-C–Fe 2.011(5)A]. There are five terminally bound CO ligands, three attached to the iron atom and one to each tungsten. In addition, the tungsten atom σ-bonded to the alkyne carries a CO group which semi-bridges the W–W edge [W–C-0 164.9(7)°]. Crystals of (6) are triclinic, space group P, Z= 2, in a unit cell with a= 8.694(2), b= 12.540(4), c= 13.365(7)A, α= 88.03(4), β= 108.44(3), and γ= 97.54(2)°. The structure has been refined to to R 0.049 (R′ 0.050) for 3 916 reflections having 2θ⩽ 50° collected at room temperature. The molecule has a structure very similar to that of (3) except that an oxygen atom has replaced the terminal CO ligand bonded to the tungsten atom µ-η2 co-ordinated to the alkyne.

Chemistry of the metal carbonyls. Part 79. Synthesis and X-ray crystal structures of [N(PPh3)2][Fe2Pt2(µ-H)(µ-CO)3(CO)5(PPh3)2], [Fe2Pt2(µ-H)2(CO)8(PPh3)2], and [Fe2Pt(CO)8(cyclo-C8H12)

Tetraethylammonium or bis (triphenylphosphine)iminium salts of the anion [Fe2(µ-H)(µ-CO)2(CO)6]– react with the complex [Pt(C2H4)2(PPh3)] in tetrahydrofuran to give the di-irondiplatinum compounds [R][Fe2Pt2(µ-H)-(µ-CO)3(CO)5(PPh3)2][R = NEt4+ or N(PPh3)2+]. The structure of the N(PPh3)2+ salt was established by a single-crystal X-ray diffraction study; the crystals are monoclinic, space group P21/c, Z= 4, in a unit cell with lattice parameters a= 25.05(3), b= 14.28(1), c= 23.99(2)A, and β= 106.84(7)°. The structure has been refined to R 0.059 (R′ 0.061) for 8 768 independent reflections to 2θ⩽ 50°[(Mo-Kα)X-radiation] collected at 200 K. The N (PPh3)2+ cation is bent [P–N–P 138.1(8)°], while the metal framework of the anion consists of a cluster of Fe2Pt2 atoms [Pt–Pt 2.966(1); Pt–Fe 2.756(2), 2.626(2), 2.555(2), and 2.562(2); Fe–Fe 2.522(2)A], arranged such that a Fe2 Pt triangle, edge-bridged by three CO ligands, is capped by a platinum atom carrying a terminal CO ligand and PPh3 group. The four remaining CO ligands are terminally bonded in pairs to the two iron atoms, while the platinum atom in the triangle carries a PPh3 group. Although not located in the X-ray diffraction study, evidence is presented that the hydrido-ligand bridges the longest of the four Fe–Pt separations. Protonation of the salts affords the neutral complex [Fe2Pt2(µ-H)2(CO)8(PPh3)2], also characterised by an X-ray diffraction study. Crystals are monoclinic, space group P21/c, Z= 4, in a unit cell with lattice parameters a= 10.83(2), b= 16.00(4), c= 27.88(4)A, and β= 99.40 (11)°. The structure has been refined to R 0.056 (R′ 0.060) for 2 474 independent reflections to 2θ⩽ 40° at 200 K. The structure consists of an Fe2Pt2 core [Pt–Pt 2.998(2); Pt–Fe 2.696(3), 2.694(3), 2.631(3), and 2.604(3)A], with each iron atom bonded to three CO ligands and each platinum atom bonded to a CO and a PPh3 group. The hydrido-ligands are considered to bridge the two longer Fe–Pt edges. The X-ray studies allow an understanding of the 1H and 31P n.m.r. data for the two Fe2Pt2 species, both of which undergo dynamic behaviour in solution. Reactions of the compound [Pt(C2H4)2(PPh3)] or [Pt(cod)(C8H13)][BF4](cod = cyclo-octa-1,5-diene) with the salt [NEt3H][Fe3(µ-H)(µ-CO)(CO)10] afford the compounds [NEt3H][Fe3Pt(µ-H)(µ-CO)(CO)10(PPh3)] and [Fe2Pt(CO)8(cod)], respectively. The latter was studied by X-ray crystallography; crystals are orthorhombic, space group P2121, Z= 4, in a unit cell of dimensions a= 12.321 (11), b= 9.442(7), and c= 15.707(16)A. The structure has been refined to R 0.050 (R′ 0.050) for 1 637 independent reflections to 2θ⩽ 55° at 200 K. The molecule consists of a triangle of metal atoms [Fe–Pt 2.561 (3) and 2.553(3); Fe–Fe 2.704 (4)A]; each iron atom carries four terminally bound CO ligands, and the platinum atom is η4 bonded to the cod group.

Chemistry of the metal carbonyls. Part 77. Some reactions of the platinumtriosmium complexes [Os3Pt(µ-H)2(CO)10(PR3)] with donor molecules; X-ray crystal structures of [Os3Pt(µ-H)2(CO)10(PPh3)2] and [OsPt2(CO)5(PPh3)2(µ3-MeC2Me)

The compounds [Os3Pt(µ-H)2(CO)10(PR3)] react with CO, PPh3, or AsPh3 to give complexes [Os3Pt(µ-H)2(CO)10(PR3)L][PR3= P(cyclo-C6H11)3, L = CO; PR3= PPh3 or AsPh3]. Hydrogen-1 and 31P n.m.r. data for the compounds are discussed, and a single-crystal X-ray diffraction study has been carried out on the compound [Os3Pt(µ-H)2(CO)10(PPh3)2], crystals of which are triclinic, space group P1, Z= 2, in a unit cell with lattice parameters a= 14.427(7), b= 12.793(5), c= 14.151(6)Å, α= 92.33(3), β= 120.87(3), and γ= 91.06(4)°. The structure has been refined to R 0.041 (R′ 0.044) for 5 794 independent reflections (2.9 ⩽ 2θ⩽ 60°, Mo-KαX-radiation) collected at 200 K. The four metal atoms adopt a butterfly arrangement in contrast to the tetrahedral cluster structure of the 58-electron precursors [Os3Pt(µ-H)2(CO)10(PR3)]. In [Os3Pt(µ-H)2(CO)10(PPh3)2] the metal–metal bonding distances are Os–Pt 2.717(1) and 2.848(1)Å, and Os–Os 2.773(1), 2.914(1), and 3.043(1)Å. Evidence is presented for the two hydrido-ligands bridging the longer Os–Pt and Os–Os bonds. One triphenylphosphine ligand is attached to platinum and the other to osmium, and all the carbonyl ligands are terminally bound. Reaction of [Os3Pt(µ-H)2(CO)10(PPh3)] with but-2-yne affords a mixture, from which five polynuclear metal complexes were isolated and studied by i.r. and n.m.r. spectroscopy. None of these products contained the Os3Pt cluster of the precursor. One of the complexes was characterised as [OsPt2(CO)5(PPh3)2(µ3-MeC2Me)] and its structure established by X-ray diffraction. Crystals are monoclinic, space group P21/c, Z= 4, in a unit cell of dimensions a= 11.143(8), b= 17.458(12), c= 23.443(15)Å, and β= 113.82(5)°. The structure has been refined to R 0.031 (R′ 0.033) for 4 438 independent reflections (2.9 ⩽ 2θ⩽ 55°, Mo-KαX-radiation) collected at 200 K. The metal atoms form an isosceles triangle [Os–Pt 2.662(2)(mean), Pt–Pt 3.033(2)Å] bridged by a face-bonding but-2-yne molecule whose orientation with respect to the triangle is µ3(η2-‖). The osmium atom carries three terminal CO ligands, and each platinum a CO and PPh3 group such that there is a cisoid arrangement OCPtPtCO; the Pt–Pt separation of 3.033(2)Å, however, suggests that there may be little direct metal–metal interaction.

Synthesis, structure and characterization of Fe 3(CO) 10S, a new iron carbonyl sulphide

The new complex Fe 3(CO) 10S has been prepared by treating Fe 3(CO) 12 with methanolic NaOH and acidifying the solution in the presence of Na 2SO 3. X-ray analysis has shown the molecule to have an Fe 3S trigonal pyramidal core, one μ 3- and nine terminal CO ligands. The compound shows fluxional behaviour in solution.

Synthesis and structure of (.eta.-C5H5)W(PPh3)(CO)(CSPh): transformation of a thiocarbonyl ligand into a carbyne ligand

The arylation reaction (eta-C/sub 5/H/sub 5/)W(PPh/sub 3/)(CO)(CS)I + LiPh ..-->.. (eta-C/sub 5/H/sub 5/)W(PPh/sub 3/)(CO)(CSPh) + LiI (5) reduces the multiple bonding in the terminal CS ligand of (eta-C/sub 5/H/sub 5/)W(PPh/sub 3/)(CO)(CS)I to a C-S single bond in the carbyne product. The previously reported alkylation (Ph/sub 2/PCH/sub 2/CH/sub 2/PPh/sub 2/)/sub 2/W(CO)(CS) + MeOSO/sub 2/F ..-->.. (Ph/sub 2/PCH/sub 2/CH/sub 2/PPh/sub 2/)/sub 2/W(CO)(CSMe)/sup +/SO/sub 3/F/sup -/ (1), and Lewis adduct formation reactions of terminal CS groups in electron-rich complexes presumably also yield CSR carbyne complexes. These results suggest that similar adducts of terminal CO ligands could be reasonable intermediates in catalytic reactions of carbon monoxide which lead to the cleavage of the carbon-oxygen triple bond. A single crystal of (eta-C/sub 5/H/sub 5/)W(PPh/sub 3/)(CO)(CSPh) approx. 0.2 x 0.15 x 0.4 mm was chosen for the x-ray diffraction study. The average distance from the tungsten to the cyclopentadienyl carbon atoms is 2.366 A. Data were given for the other ligands. 1 figure. (DP)

Infrared spectroscopic studies on metal carbonyl compounds : XVI. Analysis of the CO stretching region of the trimeric thiolatocobalt carbonyl complexes Co 3(CO) 4(SR) 5. The question of terminal-bridging coupling in force constant calculations

The analysis of the infrared spectrum of Co 3(CO) 4(SCH 3) 5 in the CO stretching region shows that not even the use of the 13CO isotopic frequencies can provide proof that the interactions between terminal and bridging CO ligands have non-zero values. Thus the neglect of these interactions in force constant calculations is a justified procedure.

Crystal structure of tri-µ-carbonyl-pentacarbonylbis-(π-cyclopentadienylrhodio)di-iron(Rh–Rh)(Fe–Fe)(4Rh–Fe), (π-C5H5)2Rh2Fe2(CO)8

The molecular structure of (π-C5H5)2Rh2Fe2(CO)8, has been determined from X-ray diffraction studies. The compound crystallizes in the centrosymmetric orthorhombic space group Pnma(D2h16, No. 62) with a= 17·979(15), b= 12·079(12), c= 9·386(8)A and Z= 4. A full three-dimensional analysis has led to the location of all non-hydrogen atoms. The structure has been refined by least-squares methods to R 7·90% for the 627 unique non-zero reflections. The molecule has crystallographically imposed Cs symmetry with the four metal atoms defining an irregular tetrahedron with Rh–Rh 2·648(3), Rh–Fe 2·570(5)–2·598(5), and Fe–Fe 2·539(7)A. The π-C5H5 ligands and a bridging carbonyl group are associated with the two rhodium atoms while there are three terminal CO ligands attached to Fe(1) and two to Fe(2).An unusual feature of the structure is the presence of two asymmetric carbonyl bridges, Fe(2)–CO–Rh and Fe(2)–CO–Rh′, with Fe–C 1·79(4) and Rh–C 2·18(3)A. The overall disposition of ligands around the tetrahedral metal-atom core is such that it proves impossible to assign 18 outer valence electrons to each metal atom.