S.P. Gubin

Synthesis and structure of polynuclear carbonylphosphine clusters of palladium

Abstract Reductive condensation of Pd(OAc)2 in dioxane in the presence of CO and PR3 (R = Et, Bun) with addition of CF3COOH leads to the formation of decanuclear Pd10(μ3-CO)4(μ2-CO)8(PBun3)6 (I) and Pd10(CO)14(PBun3) (II) at Pd(OAc)2:PR3 molar ratios of 1:4–1:10 and 1:1.5–1:2.5, respectively. The use of CH3COOH instead of CF3COOH results in tetranuclear clusters Pd4(CO)5(PR3)4 (III) and Pd4(μ2-CO)6(PBun3) (IV). I ⇌ III and III → IV transformations occur in organic media. The structures of I (space group P21/n, Z = λMo, 12125 independent reflections, R = 0.047) and IV (Pz:3, Z = λMo, 3254 reflections, R = 0.098) were established by X-Ray diffractions analysis. Cluster I is a 10-vertex Pd10 polyhedron, an octahedron with four unsymmetrically centered non-adjacent faces. The average PdPd distances in the octahedron are 2.825 A, in the eight short Pdoct.Pdcap. bonds with the “equatorial” Pd atoms of the inner octahedron, bridged by the μ2-CO ligands, are 2.709 A, and in the four elongated (without bridging CO groups) bonds with the apical Pd atoms of the octahedron are 3.300–3.422 A. The PBun3 ligands are coordinated to the apical Pd atoms and the capping atoms (PdP 2.291–2.324 A). Cluster IV is tetrahedral, with the CO ligands symmetrically bridged; PdPd 2.778–2.817; PdP 2.232–2.291; PdC 2.06 A (average).

Synthesis and x-ray structure of 10-vertex palladium carbonylphosphine cluster with minimal PBun3 content

Abstract Synthesis of the carbohylphosphine cluster Pd10(CO)14(PBun3)4 (I), a product of substitution of two PBun3 ligands by terminal CO groups in the Pd10(CO)12(PBun3)6 cluster II, was carried out, and the structure of I (λ Mo, 3200 reflections, R = 0.098) was established by X-ray analysis. The Pd10 polyhedron is a four-capped octahedron with unsymmetrical caps. The average Pd—Pd distances in the inner octahedron are 2.824 A and PdPoct—Pdcap are 2.706 A, 3.149, 3.172 A (two independent molecules). The steric effects in molecles I and II, and their influence on the stability of the cluster are discussed.

Synthesis of heteronuclear carbonyl-carbide clysters of transition metals via vertex replacement in a metal polyhedron. X-ray crystal structures of the bimetallic tetragonal-pyramidal [Fe4CoC(CO)14]− and the trimetallic octahedral Fe4CoRhC(CO)16 clusters

Abstract The successive degradation of the closo -octahedral iron carbonyl clusters with an interstitial C atom and addition of the metal carbonyl unit of different metal atoms to the resultant nido-tetragonal-pyramidal clusters lead to replacement at the vertex of octahedrons resulting in the bimetallic [Fe 5 CoC(CO) 16 ] − (I) and [Fe 4 CoC(CO) 14 ] − (II) anions as well as trimetallic Fe 4 CoRhC(CO) 16 (III) and [Fe 4 CoPdC(CO) 15 ] − (IV) clusters. An X-ray investigation of II and III revealed the nido-tetragonalpyramidal cluster structure in II with the Co atom in the basal face and in III the octahedral cluster structure with a cis-arrangement of the Co and Rh heteroatoms. The Co atom in II and the Co and Rh atoms in III are disordered over the pairs of stereochemically equivalent vertices of the metal polyhedron inside the ordered ligand polyhedron.

Nut-in-the-nutshell type of metal cluster coordination by the ligands. X-Ray investigation of two carbonyl clusters [RhFe5C(CO)16]− and [Rh5Fe(CO)16]− with a specific disorder of the metal polyhedron

Abstract An X-ray investigation of the two tetraethylammonium salts, Et4N+[RhFe5C(CO)16]− (I) and Et4N+ [Rh5Fe(CO)16]− (II) containing octahedral cluster anions (−120°C, λ(Mo), R = 0.035 (I) and 0.033 (II)) has been carried out. In both anions identical CO-ligand configurations corresponding to the minimum ligand repulsion are realized. The orientation of the disordered M5M′ cluster nucleus relative to the CO-shell differs in I (12 terminal and 4 semi-bridging CO) and II (12 terminal and 4 μ3-CO).

OPTICALLY ACTIVE PENTANUCLEAR WING-TIP BUTTERFLY HETEROTRIMETALLIC CLUSTERS

The pentanuclear heterotrimetallic clusters of formula Fe 3 MC(CO) 12 M′L {M = Co, M′ = Au, L = PPh 3 ( XIV ); M = Co, M′ = Pd. L = η 3 -C 3 H 5 ( XV ); M = Co, M′ = Pd, L = η 3 - β -pinenyl, C 10 H 15 ( I ); M = Rh, M′ = Au, L = PPh 3 ( XVI ); M = Rh, M′ = Pd. L = η 3 -C 3 H 5 ( XVII ); M = Rh, M′ = Pd, L = η 3 -C 10 H 15 ( II )} have been obtained by the have been obtained by the addition of corresponding M′L fragments to heterometallic butterfly [Fe 3 MC(CO) 12 ] − , where M = Co ( XI ) or Rh ( X ); the butterfly XI has been isolated in reductive degradation of Co-containing clusters [Fe 3 Co 3 C(CO) 15 ] − or [Fe 4 CoC(CO) 14 ] − . The X-ray crystal structures of XIV and XV have been determined. Both structures have approximately the same pentanuclear heterotrimetallic cluster cores with M′L groups in bridging position linking wing tips. According to the refinement data, the Co atoms in XIV and XV are placed in the basal position of the butterfly. EXAFS data for XV suggest a structural flexibility of the metal core in solution. Absorption (AB) and circular dichroism (CD) spectra of two optically active clusters I and II with the same ‘wing-tip’ butterfly structure were investigated and compared with those for the starting [Pd( η 3 - β -C 10 H 15 )Cl] 2 chiral complex. The noticeable Cotton effects (CE) in the CD spectra induced in electron transitions of cluster metallochromophores demonstrate a strong manifestation of the vicinal optical activity.

Chiroptical properties of heterotrimetallic ‘wing-tip’ butterflies; synthesis and crystal structure of (μ-H)Ru2Fe2PdC(CO)12 (η3-ß-C10H15)

Abstract HRu2Fe2PdC(CO)12 (η3-s-C10H15) cluster was prepared in the reaction of (Et4N) [HFe2Ru2C(CO)12] with [Pd(η3-s-C10H15)Cl]2. X-ray structural study of HRu2Fe2PdC(CO)12 (η3-s-C10H15) (where s-C10H15 is s-pinenyl) revealed a wing-tip butterfly geometry of the metal core and (1R, 2S, 3S, 5R) absolute configuration for both crystallography independent molecules in the crystal. Chiroptical properties of this cluster are compared with other clusters containing a Pd(η3-s-C10H15) fragment and discussed.