Cluster Core Isomerism Induced by Crystal Packing Effects in the [HCo₁₅Pd₉C₃(CO)₃₈]^2– Molecular Nanocluster

Abstract

This article describes a rare case of cluster core isomerism in a large molecular organometallic nanocluster. In particular, two isomers of the [HCo 15 Pd 9 C 3 (CO) 38 ] 2– nanocluster, referred as TP-Pd 9 and Oh-Pd 9 , have been structurally characterized by single-crystal X-ray crystallography as their [NMe 3 (CH 2 Ph)] 2 [HCo 15 Pd 9 C 3 (CO) 38 ]·CH 2 Cl 2 (ca. 1:1 TP-Pd 9 and Oh-Pd 9 mixture), [NMe 3 (CH 2 Ph)] 2 [HCo 15 Pd 9 C 3 (CO) 38 ]·2CH 2 Cl 2 (mainly TP-Pd 9 ), [NEt 3 (CH 2 Ph)] 2 [HCo 15 Pd 9 C 3 (CO) 38 ]·CH 2 Cl 2 (mainly TP-Pd 9 ), [MePPh 3 ] 2 [HCo 15 Pd 9 C 3 (CO) 38 ]·2.5CH 2 Cl 2 (mainly TP-Pd 9 ), and [MePPh 3 ] 2 [HCo 15 Pd 9 C 3 (CO) 38 ] (Oh-Pd 9 ) salts. The cluster core of TP-Pd 9 is a tricapped trigonal prism, whereas this is a tricapped octahedron in Oh-Pd 9 . The presence in the solid state of the Oh-Pd 9 or TP-Pd 9 isomers depends on the cation employed and/or the number and type of co-crystallized solvent molecules. Often, mixtures of the two isomers, within the same single crystal or as mixtures of different crystals within the same crystallization batch, are obtained. Structural isomerism in organometallic nanoclusters is discussed and compared to that in Au–thiolate nanoclusters.

Polymerization Isomerism in [{MFe(CO)4}n]n− (M = Cu, Ag, Au; n = 3, 4) Molecular Clusters Supported by Metallophilic Interactions

“…The new case of polymerization isomerism herein described adds to the other isomerism types (enantiomerism, core isomerism, staple isomerism, complex isomerism, surface ligand isomerism, and dynamic permutational isomerism) previously reported for molecular metal clusters. − Despite the different intrinsic nature of Au–thiolate and organometallic (carbonyl) molecular clusters, there seems to be some general analogies among these types of atomically precise clusters. , Overall, as our knowledge of the molecular structures of metal clusters of increasing sizes is growing, concepts such as structural isomerism, that have been developed for molecular coordination and organometallic chemistry, find their way also in the field of metal clusters, nanoclusters, and nanoparticles. − …”

“…Cluster core isomerism was, actually, documented for the first time in the case of the [Pt 3 (μ-PPh 2 ) 3 Ph­(PPh 3 ) 2 ] organometallic cluster . Moreover, surface ligand isomerism and dynamic permutational isomerism were subsequently discovered for molecular organometallic clusters. − These discoveries reveal that isomerism in molecular clusters is a very rich topic and further exciting advancement may be envisioned. To widen the scope of isomerism in molecular clusters, we report herein an unique case of polymerization isomerism in [{MFe­(CO) 4 } n ] n − (M = Cu, Ag, Au; n = 3, 4) molecular clusters supported by metallophilic interactions.…”

Polymerization Isomerism in Co-M (M = Cu, Ag, Au) Carbonyl Clusters: Synthesis, Structures and Computational Investigation

“…Conversely, the two isomers of [Pt 9 (CO) 16 (R-dppp)] 2− (R-dppp = ( R )-Ph 2 PCH(Me)(CH 2 PPh 2 ) are due to two different orientations of the R-dppp ligand bonded to the surface of the cluster [ 29 ]. More recently, cluster core isomerism induced by acid-base reactions as well as crystal packing effects has been fully elucidated in the case of the [HCo 15 Pd 9 C 3 (CO) 38 ] 2− molecular carbonyl nanocluster [ 30 , 31 ].…”

Synthesis, Structural Characterization, and DFT Investigations of [MxM′5–xFe4(CO)16]3– (M, M′ = Cu, Ag, Au; M ≠ M′) 2-D Molecular Alloy Clusters

“…Thiolate protected alloy nanoclusters and, generally speaking, Au-based alloy nanoclusters have been largely investigated in recent years, as part of the great interest for atomically precise and ultrasmall Au nanoparticles. − Within this framework, we reported some years ago a few examples of molecular Au nanoclusters protected by Fe-carbonyl fragments, that is, [Au 21 {Fe­(CO) 4 } 10 ] 5– , [Au 22 {Fe­(CO) 4 } 12 ] 6– , [Au 28 {Fe­(CO) 3 } 4 {Fe­(CO) 4 } 10 ] 8– , and [Au 34 {Fe­(CO) 3 } 6 {Fe­(CO) 4 } 8 ] 10– . This may be viewed as an organometallic approach to metal nanoparticles, that includes also the [Ni 32 Au 6 (CO) 44 ] 6– and [Ni 12 Au 6 (CO) 24 ] 2– clusters containing a Au 6 core stabilized by Ni–CO moieties , and Pd clusters protected by Co-carbido-carbonyl fragments, that is, [H 4– n Co 20 Pd 16 C 4 (CO) 48 ] n − ( n = 2–4), [H 3– n Co 15 Pd 9 C 3 (CO) 38 ] n − ( n = 0–3), and [Co 13 Pd 3 C 3 (CO) 29 ] − . Thus, planar organometallic species such as [M 3 Fe 3 (CO) 12 ] 3– (M = Cu, Ag, Au), , [M 4 Fe 4 (CO) 16 ] 4– (M = Ag, Au), , and [M 5 Fe 4 (CO) 16 ] 3– (M = Cu, Ag, Au) ,, may be viewed as 2-D molecular clusters, consisting of triangular M 3 , square M 4 , or centered rectangular M 5 2-D cores stabilized by Fe­(CO) 4 fragments.…”