Showing papers by "Louis J. Farrugia published in 1981"

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)]

Abstract: 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)A, 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)A, and Os–Os 2.773(1), 2.914(1), and 3.043(1)A. 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)A, 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)A] 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)A, however, suggests that there may be little direct metal–metal interaction.

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)]

Abstract: 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 76. Platinum–osmium carbonyl complexes derived from decacarbonyldi-µ-hydrido-triosmium; X-ray crystal structure of [Os3Pt(µ-H)2(CO)10{P(cyclo-C6H11)3}]

Abstract: Reactions between [OS3(µ-H)2(CO)10] and the compounds [Pt(C2H4)2(PR3)][PR3= P(cyclo-C6H11)3, PPh3, or PBut2Me] afford tetranculear metal complexes [Os3Pt(µ-H)2(CO)10(PR3)]. Examination of the variable-temperature 1H n.m.r. spectra of these ‘58-electron’ clusters reveals dynamic behaviour with site exchange of the two hydrido-ligands, the energy barrier for this process for the PBut2Me derivative being ca. 58 kJ mol–1. In order to establish the molecular structure of these complexes a single-crystal X-ray diffraction study was made on the compound containing the P(cyclo-C6H11)3 ligand. Crystals are monoclinic, space group P21/c, Z= 4, in a unit cell of dimensions a= 11.822(4), b= 16.584(5), c= 17.763(9)A, and β= 108.10(4)°. The structure has been refined to R 0.035 (R′ 0.038) for 5 737 reflections to 2θ < 60°(Mo-Kα, X-radiation) collected at 200 K. The metal atoms adopt a slightly asymmetric tetrahedral structure [Os–Os 2.777(1), 2.741(1), and 2.789(1)A; Os–Pt 2.791(1), 2.832(1), and 2.863(1)A]. The platinum atom is bonded to a CO group and to the P(cyclo-C6H11)3 ligand, and each osmium is attached to three CO groups. The hydrido-ligands bridge the longer of the Os–Os and Os–Pt bonds, as deduced from observation of residual electron densities, from widening of certain Pt–Os–CO and Os–Os–CO angles, from staggered conformations of two of the Os(CO)3 groups with respect to the two longer edges of the tetrahedron, and from calculation of potential energy minima.

Chemistry of the metal carbonyls. Part 78. Synthesis and X-ray crystal structures of [NiOs3(µ-H)2(µ-CO)2(CO)8(PPh3)2] and [Os3Rh(µ-H)2(acac)(CO)10](acac = acetylacetonate)

Abstract: The zerovalent nickel compound [Ni(C2H4)(PPh3)2] reacts with [Os3(µ-H)2(CO)10] to give the 60 valence electron cluster complex [NiOs3(µ-H2)(CO)10(PPh3)2], the structure of which has been established by a single-crystal X-ray diffraction study. It crystallises in the monoclinic space group P21/n with four molecules in a cell of dimensions a= 15.579(6), b= 17.205(4), c= 18.976(5)A, and β= 99.97(3)°. The structure has been determined from 8 595 unique reflections (2.9 ⩽ 2θ⩽ 55°, Mo-KαX-radiation) collected at 190 K, and refined to R 0.038 (R′ 0.042). The metal atoms form a slightly distorted tetrahedron with two Ni–Os edges each bridged by a carbonyl group, and with the third Ni-Os edge and an Os–Os bond bridged by hydrido-ligands. Although the latter were not located by the diffraction study their assigned positions are argued on a variety of other evidence. The nickel atom carries one PPh3 ligand, while the second PPh3 group is bound to an osmium atom. The unsaturated triosmium compound [Os3(µ-H)2(CO)10] also reacts with [Rh(acac)(C2H4)2](acac = acetylacetonate) affording in high yield the cluster complex [Os3Rh(µ-H)2(acac)(CO)10]. An X-ray diffraction study on a single crystal revealed that it was triclinic, space group P(no. 2), Z= 2, in a unit cell of dimensions a= 8.759(3), b= 9.463(2), c= 13.680(4)A, α= 100.59(2), β= 93.86(2), and γ= 107.84(2)°. The structure has been refined to R 0.052 (R′ 0.059) for 4 240 independent reflections (2.9 ⩽ 2θ⩽ 60°, Mo-KαX-radiation) collected at 200 K. The four metal atoms adopt a ‘butterfly’ configuration. The pentane-2,4-dionato-ligand is chelated to the rhodium atom at one extremity but one of its oxygen atoms also bridges to an Os atom forming the other wing-tip of the ‘butterfly’, so that this Os–Rh separation is 3.292(2)A. The pentane-2,4-dionato-group thus functions as a five-electron donor, hence the cluster has 60 valence electrons. The rhodium atom also carries a carbonyl ligand, and this, and the remaining nine carbonyls on the osmium atoms, are all terminally bound. On the basis of 1H n.m.r. studies, osmium–osmium distances, and other evidence the two hydrido-ligands bridge two of the Os–Os bonds. The compound is chemically unsaturated forming an adduct with triphenylphosphine; n.m.r. studies (1H and 31P) show that the PPh3 group becomes attached to the rhodium atom of the cluster.

Chemistry of the metal carbonyls. Part 80. Diosmiumdiplatinum carbonyl complexes derived from tetracarbonyldihydrido-osmium. X-Ray crystal structure of [Os2Pt2(µ-H)2(CO)8(PPh3)2]

Abstract: The complexes [Pt(C2H4)2(PR3)] react at room temperature with [OsH2(CO)4] in light petroleum to give diosmiumdiplatinum compounds [Os2Pt2(µ-H)2(CO)8(PR3)2](R = Ph, cyclo-C6H11, or Me), the spectroscopic properties of which are reported. The molecular structure of the triphenylphosphine derivative was established by an X-ray diffraction study. The four metal atoms form a ‘butterfly’ cluster with the two osmium atoms at the ‘hinge’(Os–Os = 2.7814A) and the two platinum atoms at the ‘wingtips’(Pt ⋯ Pt = 3.2060A). The molecule has two-fold rotational symmetry crystallographically imposed, the two Os–Pt distances being 2.8629 and 2.7089A; the longer bonds are hydrido-bridged. The platinum atoms each carry one carbonyl group and a triphenylphosphine ligand. Crystals of [Os2Pt2(µ-H)2(CO)8(PPh3)2] are monoclinic, a= 15.488(4), b= 12.949(3), c= 21.364(5)A, β= 93.71 (2)°, space group C2/c. The structure was solved by heavy-atom methods and has been refined to R 0.031 (R′ 0.028) for 4 192 reflections.