Crystal structure of nonacarbonylhexakis(triphenylphosphane)- nonapalladiumgold hexafluoridophosphate, [Pd9Au(CO)9(PPh3)6](PF6)

Abstract

C 129 H 114 AuF 6 O 12 P 7 Pd 9 ,trigonal, R3 (no. 148), a =22.520(4) Å, c =39.433(7) Å, V =17319 Å 3 , Z =6, R gt(F) =0.047, wRref(F 2 ) =0.129, T =120 K. Source of materialSuitable crystals for X-ray diffraction analysis were obtained from the crude product resulting of the reaction of [Pd 3(CO)3(P-tBu 3)3]with [Au(PPh3)Cl] in presence of TlPF6.The crystals were grown by slow diffusion of diethylether in aCH 2 Cl 2 solution under carbon monoxide atmosphere at 4°C. Experimental detailsThe data were not corrected for absorption, but the data collection mode with high redundancy, partially takes the absorption phenomena into account (62 images, DF =2°, 29272 reflections measured for 7791 independent reflections). The PF 6 anion is disordered with aP-F bond on 3 axis. The solvent molecule is also disordered, the ring atoms were refined isotropically and constraints on bond lengths were applied. All the Hatoms were calculated with AFIX and included in the refinement with acommon isotropic temperature factor (U iso =0.065 Å 2 ). The Hatoms of the solvent molecules were not localized. DiscussionMolecular clusters are fascinating compounds of nanometrical size, comprising several metal atoms (from three to afew hundreds) surrounded by aligand shell, with potential applications in the nano field [1] and also in catalysis [2][3][4][5]. They can be used as such as homogeneous catalysts, or as heterogeneous catalysts if they are first deposited onto asupport and then activated to produce supported nanoparticles. In the latter area, the use of Au-Pd mixed metal clusters as precursors for mixed-metal nanoparticles is of particular interest because of the number of catalysed reactions by this alloy [6][7][8][9]. Nevertheless, only fifteen Au-Pd clusters were fully characterized, what is relatively poor compared to the Au-Pt analogues [10]. Thus, succeeding in obtaining the X-ray structure of such entities remains achallenge. In our attempts to synthesize Au-Pd clusters from homonuclear palladium clusters, the compound [Pd9Au(CO)9(PPh3)6](PF6)was obtained in very low yield. The synthesis of this cluster was based on the known preparation of [Pd14Au2(CO)9(PMe3)11](PF6)2 obtained by reacting [Pd8(CO)8(PMe3)7]w ith [Au(PCy 3 )Cl] in the presence of TlPF6 [11]. The cluster [Pd 9 Au(CO) 9 (PPh 3 ) 6 ](PF 6 )c rystallizes with three molecules of tetrahydrofuran by molecule of cluster (this solvent was used in the work-up of the reaction to obtain the crude product before crystallization). The structure of the metallic core of this cluster can be viewed as an octahedron of palladium atoms in which each bond of one triangular face is bridged by an additional Pd atom, the same face being also capped by the gold atom. Six terminally bounded PPh3 are observed with six bridging (m 2 )and three capping (m3)CO. The Pd-Au distance is 2.8369(7) Å.Due to the position of the gold atom, the Pd-Pd distances of the capped triangular face aree longated compared to the other Pd-Pdbonds of the octahedron (3.0917(9) Å vs. 2.750 Å (average)). ...

High-Yield Synthesis of PPh3-Ligated Decanuclear Tl–Pd Cluster, Pd9[Tl(acac)](CO)9(PPh3)6: Comparative Analysis of Tl(I)–Pd(0) Bonding Connectivities with Known Tl–Pd Clusters and Resulting Insight Concerning Their Dissimilar Dynamic Solution Behavior

“…The Pd 9 (CO) 9 L 6 fragment in 2 is geometrically analogous to that in 1 . However, in 2 the Tl(I) is alternatively attached to a trigonal-bipyramidal Co(CO) 3 L monoanion by resulting electron-pair donation from the cobalt to the Tl(I).…”

How innocent is thallium(i)? Corrected formulations of [Tl2Pd14(CO)9(PMe3)11][PF6]2 and [TlPd9(CO)9(PPh3)6][PF6] clusters previously reported as corresponding Au2Pd14 and AuPd9 clusters

“…By the reaction of Pd 10 (CO) 12 (PPh 3 ) 6 , with TlPF 6 and the stoichiometric amount of PPh 3 we also prepared (B70% yield) and structurally characterized the [TlPd 9 (CO) 9 (PPh 3 ) 6 ][PF 6 ] (2a-Ph) cluster 10,11 in order to show that its refined TlPd 9 crystal structure is crystallographically isomorphous with that of the cluster previously reported incorrectly by Tinant and co-workers 12 in 2008 as the corresponding AuPd 9 . Their compound was obtained in very low yield from an irreproducible reaction (as stated by the authors) of Pd 3 (CO) 3 (PBu t…”

“…3 ) 3 with Au(PPh 3 )Cl in the presence of TlPF 6 and formulated as [AuPd 9 (CO) 9 (PPh 3 ) 6 ][PF 6 ], , though the authors further stated that they could not exclude the presence of thallium instead of gold. 12 Its metal framework consists of the Pd(A) 3 Pd(B) 3 distorted octahedron with three wing-tip Pd(C) atoms attached to the Pd(A) 3 face capped by the Tl(I) atom. Fig.…”

“…We suggest that the existence of the known octahedral-containing TlPd 9 clusters rather than corresponding unknown AuPd 9 ones arises from the positive stabilization influence of the 6s 2 electron-pair of 6s 2 5d 10 Tl(I) as a two-electron donor ligand (relative to that of 6s 0 5d 10 Au(I)). Its inclusion enables the octahedral metal polyhedron to conform to the Wade-Mingos bonding model 14 The reactions of CO/PR 3 -ligated Pd(0) clusters with Au(I) chloride salts in the presence of TlPF 6 that resulted in the formation of Tl-Pd clusters instead of Au-Pd ones 1,2,12 are in sharp contrast to the reactions of CO/PR 3 -ligated Pt(0) clusters with the same reagents that give rise to the targeted Au-Pt clusters. 15 Furthermore, in Tl-Pt clusters the thallium atom may be substituted by the [AuPR 3 ] + fragments.…”