Gas-phase reactivity of ruthenium carbonyl cluster anions

Abstract

Partially-ligated anionic ruthenium carbonyl clusters react with alkenes, arenes, and alkanes in the gas phase; the products undergo extensive C-H activation and lose dihydrogen and carbon monoxide under collision-induced dissociation conditions. Triethylsilane and phenylsilane are also reactive towards the unsaturated clusters, and oxygen was shown to rapidly break down the cluster core by oxidative cleavage of the metal-metal bonds. These qualitative gas-phase reactivity studies were conducted using an easily-installed and inexpensive modification of a commercial electrospray ionization mass spectrometer. Interpretation of the large amounts of data generated in these studies is made relatively straightforward by employing energydependent electrospray ionization mass spectrometry (EDESI-MS). here are many examples of reactions between molecules and metal cluster ions in the gas phase, and the area has been well reviewed [1,2]. Of intense current interest are those systems in which catalytic reactions (homogeneous or heterogeneous) are modeled [3,4]. The information gleaned from these studies is particularly advantageous in systems where little or nothing is known about reactivity. Interest in the area stems from the fact that the chemistry of highly reactive, metallic nanoparticles is fundamentally difficult to study, and it is high surface area metals and metal oxides that are responsible for the most industrially important heterogeneous catalytic reactions. Any means of gaining insight into the mechanism of these reactions may prove useful in designing more efficient and more selective catalysts. The absence of surfaces, solvents, and counterions make the gas phase a considerably less complicated environment than that found in solution. Just how good the correspondence is between gas-phase and solution results is subject to active debate [5][6][7], but there is little argument that the gas phase benefits from the reduction in the number of variables, especially when dealing with complicated systems. The gas-phase reactivity of a wide variety of partially ligated clusters have been studied, including oxides [8 -11] [18]. and even some mixed species [19,20]. However, for the most part, the extent of ligation is low and, correspondingly, so is the relevance to solution chemistry. Homogeneous catalysis is generally performed under conditions that are relatively mild and in which the catalysts maintain a (near) complete coordination sphere, so the comparison with nearly naked gas-phase metal clusters is somewhat tenuous (though interestingly, may more closely approximate the conditions of heterogeneous catalysis, which frequently involves unligated metal particles on a surface) [21,22].Some work has also been done on partially ligated carbonyl clusters; an early paper by Ridge [23] example by Ridge demonstrated that in a Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS), partially ligated cationic transition-metal carbonyl clusters generated by electron ionization reacted readily with cycl...

A Hypothetical Model for the Formation of Transition Metal Carbonyl Clusters Based upon 4n Series Skeletal Numbers

“…The corresponding cluster k values of the fragment should be on the increase. Very interesting extensive work on the metal carbonyls that involves stripping off the CO ligands has been done by several research groups (Butcher, et al, 2002(Butcher, et al, , 2003Crawford, et al, 2006;Critchley, et al, 1999;Dyson, et al, 2001;Henderson, et al, 1998Henderson, et al, , 2009 Table 7). Although the series and the skeletal numbers predict that each of the Re skeletal atoms except one should have a hydrogen atom, the structural determination indicates all the hydrogen atoms are bridging (Miessler, et al, 2014) as observed in borane clusters.…”

“…These opposing processes are reflected in Tables 7 and 8. The removal of CO ligands from transition metal carbonyl clusters has been an intense field of research (Critchley, et al, 1999, Douglas, et al, 2001, Butcher, et al, 2002, 2003, Crawford, et al, 2006, Henderson, et al, 2009). The silicon clusters Si n (n=4-10) were theoretically studied (Slee, et al, 1989) (Hughes, et al, 2000).…”

Unification and Expansion of Wade-Mingos Rules with Elementary Number Theory

“…For a example,Rh 6 (CO) 16 [E = 6X18 = 108, V = 6X9+16X2 = 86, k = ½ (E-V) = ½ (108-86) = 11, M-6-11-86). By moving down the M-6 column reaching M-6-11-86,then moving across the row it is found that the cluster belongs to the closo (C) series M-6-11-86-C(14n+2) with an octahedral geometry 8 .…”

Tailored Nanoparticles for Clean Technology–Achieving Size and Shape Control

“…However, studies by McIndoe et al [42] demonstrated that chemically synthesized atomically precise metal clusters could be used as precursors of naked metal clusters. Similarly, reactivity studies of partially ligated gas-phase metal clusters can be performed using chemically made, atomically precise clusters as a source, and easily installed and inexpensive modifications to electrospray ionization mass spectrometers [43]. Such studies demonstrate that cluster reactivity depends not only on the number of metal atoms per cluster core, but also on the number of coordinated ligands, highlighting how sensitive the electronic properties of ultrasmall particles are to modifying interactions [44,45].…”

“…Pt cubes were 19 times more active than cuboctahedra, which, in turn, were 27 times more active than octahedral particles! However, rather than shape effect, these differences were attributed to variable Ag content (43,378, and 326 ppm Ag in the cubes, cuboctahedra and octahedra, respectively), as Ag was known to lower the Pt activity in alkene hydrogenation. When the reactivity of Ag-free TTAB-stabilized Pt cubes and cuboctahedra was studied later in benzene hydrogenation [245], clear particle shape effects became apparent [247].…”