Synthesis and Crystal Structure of the [Ni32C6(CO)36]6− Hexaanion: An Extended Fragment of the M23C6 Lattice Stabilized in a Shell of Edge‐Bridging Carbonyl Ligands
Abstract:Transition metal carbonyl clusters of high nuclearity are often closely related to fragments of a metal lattice; more rarely, clusters that can be considered as an extended fragment of the lattice of a binary compound have been stabilized in a ligand shell, although some important examples of this type of cluster are known.". Metal carbonyl clusters that exhibit the above behavior are of interest since they may provide a molecular approach to new materials,l3I and may be used as models for both experimentalL4]… Show more
“…A related diagonal correspondence holds for the other redox changes. A similar behavior has previously been observed in the [H 6 - n Ni 38 (μ 8 -C) 6 (CO) 42 ] n - ( n = 5, 6) series,7c but not for the [Ru 10 (μ 6 -C)(CO) 24 ] 2- and [HRu 10 (μ 6 -C)(CO) 24 ] - pairs of clusters . In the latter case, the irreversible reduction of the dianion occurs at a more negative potential than the corresponding irreversible reduction of the isoelectronic hydride monoanion.…”
Section: Resultssupporting
confidence: 85%
“…However, these plots are less general and the fit is less significant because of the present paucity of data. 3 A linear plot of the experimental average separation between the formal electrode potentials of consecutive redox couples (Δ E av in V) as a function of nuclearity of the cluster: 1, [Fe 3 Pt 3 (CO) 15 ] n - ( n = 0−2); 2, [Co 8 C(CO) 18 ] n - ( n = 1−4);4a 3, [Ni 11 Sb 2 (CO) 18 ] n - ( n = 2−4);2e 4, [Ni 11 Bi 2 (CO) 18 ] n - ( n = 2−4);2d 5, [HFe 6 Pd 6 (CO) 24 ] n - ( n = 2−5); 6, [Ni 13 Sb 2 (CO) 24 ] n - ( n = 2−4);2c 7, [Co 13 C 2 (CO) 24 ] n - ( n = 3−6);4a 8, [Ir 14 (CO) 27 ] n - ( n = 0−2); 9, [Pt 19 (CO) 22 ] n - ( n = 3−7);4a 10, [Ag 13 Fe 8 (CO) 32 ] n - ( n = 3−5); 11, [Pt 24 (CO) 30 ] n - ( n = 1−5); 12, [Ni 32 C 6 (CO) 36 ] n - ( n = 5−10);7c 13, [HNi 38 C 6 (CO) 42 ] n - ( n = 4−8);7c 14, [Ni 38 C 6 (CO) 42 ] n - ( n = 5−9);7c 15, [HNi 36 Pt 4 (CO) 45 ] n - ( n = 4−7);15b 16, [Ni 36 Pt 4 (CO) 45 ] n - ( n = 5−9);15b 17, [HNi 38 Pt 6 (CO) 48 ] n - ( n = 3−7); 18, [Ni 38 Pt 6 (CO) 48 ] n - ( n = 5−9).…”
Section: Resultsmentioning
confidence: 99%
“…Furthermore, it suggested that the presence of an interstitial nickel atom and concomitant stabilization of the metal core imparted by the peripheral main-group elements could trigger electron-sink behavior also in carbonyl clusters. This conclusion was later authorized by electrochemical studies of [Ni 32 (μ 8 -C) 6 (CO) 36 ] 6- and [H 6 - n Ni 38 (μ 8 -C) 6 (CO) 42 ] n - ( n = 4−6), which contain highly connected (12 and 13) nickel and bulk carbide atoms . Indeed, these high-nuclearity carbide clusters display a wide redox aptitude encompassing five redox changes with features of electrochemical reversibility 7c…”
Section: Introductionmentioning
confidence: 99%
“…This conclusion was later authorized by electrochemical studies of [Ni 32 (μ 8 -C) 6 (CO) 36 ] 6- and [H 6 - n Ni 38 (μ 8 -C) 6 (CO) 42 ] n - ( n = 4−6), which contain highly connected (12 and 13) nickel and bulk carbide atoms . Indeed, these high-nuclearity carbide clusters display a wide redox aptitude encompassing five redox changes with features of electrochemical reversibility 7c…”
An investigation of the chemical and electrochemical redox behavior of the bimetallic [H(6)(-)(n)()Ni(38)Pt(6) (CO)(48)](n)()(-) (n = 4-6) clusters shows that they display electron-sink features encompassing up to six different oxidation states. As a corollary, these studies provide an indirect proof of the presence of hydride atoms where n = 4 and 5. The difference in the formal electrode potentials of consecutive redox couples of both [HNi(38)Pt(6) (CO)(48)](5)(-) and [Ni(38)Pt(6) (CO)(48)](6)(-) is almost constant and amounts on the average to ca. 0.33 and 0.28 V, respectively. Such constancy of DeltaE within each species points out the absence of a well-defined HOMO-LUMO gap in both clusters. Besides, its value is an indication of their semiconductor rather than metallic nature. A plot of the average DeltaE exhibited by the known carbonyl clusters displaying electrochemically reversible multiple redox changes versus their nuclearity suggests that the transition from semiconductor to metallic behavior might occur upon a ca. 50% increase of the today available cluster nuclearities.
“…A related diagonal correspondence holds for the other redox changes. A similar behavior has previously been observed in the [H 6 - n Ni 38 (μ 8 -C) 6 (CO) 42 ] n - ( n = 5, 6) series,7c but not for the [Ru 10 (μ 6 -C)(CO) 24 ] 2- and [HRu 10 (μ 6 -C)(CO) 24 ] - pairs of clusters . In the latter case, the irreversible reduction of the dianion occurs at a more negative potential than the corresponding irreversible reduction of the isoelectronic hydride monoanion.…”
Section: Resultssupporting
confidence: 85%
“…However, these plots are less general and the fit is less significant because of the present paucity of data. 3 A linear plot of the experimental average separation between the formal electrode potentials of consecutive redox couples (Δ E av in V) as a function of nuclearity of the cluster: 1, [Fe 3 Pt 3 (CO) 15 ] n - ( n = 0−2); 2, [Co 8 C(CO) 18 ] n - ( n = 1−4);4a 3, [Ni 11 Sb 2 (CO) 18 ] n - ( n = 2−4);2e 4, [Ni 11 Bi 2 (CO) 18 ] n - ( n = 2−4);2d 5, [HFe 6 Pd 6 (CO) 24 ] n - ( n = 2−5); 6, [Ni 13 Sb 2 (CO) 24 ] n - ( n = 2−4);2c 7, [Co 13 C 2 (CO) 24 ] n - ( n = 3−6);4a 8, [Ir 14 (CO) 27 ] n - ( n = 0−2); 9, [Pt 19 (CO) 22 ] n - ( n = 3−7);4a 10, [Ag 13 Fe 8 (CO) 32 ] n - ( n = 3−5); 11, [Pt 24 (CO) 30 ] n - ( n = 1−5); 12, [Ni 32 C 6 (CO) 36 ] n - ( n = 5−10);7c 13, [HNi 38 C 6 (CO) 42 ] n - ( n = 4−8);7c 14, [Ni 38 C 6 (CO) 42 ] n - ( n = 5−9);7c 15, [HNi 36 Pt 4 (CO) 45 ] n - ( n = 4−7);15b 16, [Ni 36 Pt 4 (CO) 45 ] n - ( n = 5−9);15b 17, [HNi 38 Pt 6 (CO) 48 ] n - ( n = 3−7); 18, [Ni 38 Pt 6 (CO) 48 ] n - ( n = 5−9).…”
Section: Resultsmentioning
confidence: 99%
“…Furthermore, it suggested that the presence of an interstitial nickel atom and concomitant stabilization of the metal core imparted by the peripheral main-group elements could trigger electron-sink behavior also in carbonyl clusters. This conclusion was later authorized by electrochemical studies of [Ni 32 (μ 8 -C) 6 (CO) 36 ] 6- and [H 6 - n Ni 38 (μ 8 -C) 6 (CO) 42 ] n - ( n = 4−6), which contain highly connected (12 and 13) nickel and bulk carbide atoms . Indeed, these high-nuclearity carbide clusters display a wide redox aptitude encompassing five redox changes with features of electrochemical reversibility 7c…”
Section: Introductionmentioning
confidence: 99%
“…This conclusion was later authorized by electrochemical studies of [Ni 32 (μ 8 -C) 6 (CO) 36 ] 6- and [H 6 - n Ni 38 (μ 8 -C) 6 (CO) 42 ] n - ( n = 4−6), which contain highly connected (12 and 13) nickel and bulk carbide atoms . Indeed, these high-nuclearity carbide clusters display a wide redox aptitude encompassing five redox changes with features of electrochemical reversibility 7c…”
An investigation of the chemical and electrochemical redox behavior of the bimetallic [H(6)(-)(n)()Ni(38)Pt(6) (CO)(48)](n)()(-) (n = 4-6) clusters shows that they display electron-sink features encompassing up to six different oxidation states. As a corollary, these studies provide an indirect proof of the presence of hydride atoms where n = 4 and 5. The difference in the formal electrode potentials of consecutive redox couples of both [HNi(38)Pt(6) (CO)(48)](5)(-) and [Ni(38)Pt(6) (CO)(48)](6)(-) is almost constant and amounts on the average to ca. 0.33 and 0.28 V, respectively. Such constancy of DeltaE within each species points out the absence of a well-defined HOMO-LUMO gap in both clusters. Besides, its value is an indication of their semiconductor rather than metallic nature. A plot of the average DeltaE exhibited by the known carbonyl clusters displaying electrochemically reversible multiple redox changes versus their nuclearity suggests that the transition from semiconductor to metallic behavior might occur upon a ca. 50% increase of the today available cluster nuclearities.
“…These clusters feature anticuboctahedral and cuboctahedral [M 13 ] kernels, respectively. Other notable examples of Ni APNCs with a high degree of metal–metal bonding include [HNi 38 (CO) 6 (μ-CO) 36 C 6 ] 5– , [Ni 32 C 6 (CO) 36 ] 6– , and [Ni 9 Te 6 (PEt 3 ) 8 ]. − The latter example features a cubic [M 9 ] kernel in which the central Ni atom is only bound by Ni metal atoms . The closely related Co cluster, [Co 9 Te 6 (CO) 8 ], is also known…”
The reaction of [Ni(1,5-COD) 2 ] (1.0 equiv), PEt 3 (0.04 equiv), SePEt 3 (0.52 equiv), and [NiCl 2 (PEt 3 ) 2 ] (0.07 equiv) in a mixture of toluene and THF results in the formation of [Ni 23 Se 12 Cl 3 (PEt 3 ) 10 ] (1), which can be isolated in moderate yield after workup. Complex 1 was characterized by NMR spectroscopy, ESI-MS, and X-ray crystallography. This open-shell nanocluster features a central [Ni 13 ] 7+ anticuboctahedral kernel, which is encapsulated by a [Ni 10 (μ-Se) 9 Cl 3 ] − shell, along with ten PEt 3 ligands and three (μ 4 -Se) 2− ligands. On the basis of our spectroscopic and crystallographic analysis, coupled with in situ spectroscopic monitoring, we believe that the previously reported nanocluster, [Ni 23 Se 12 (PEt 3 ) 13 ], is actually better formulated as [Ni 23 Se 12 Cl 3 (PEt 3 ) 10 ].
The hexacarbide clusters [H6–nNi38C6(CO)42]n− (n = 3, 4, 5, or 6) have been directly obtained from the reaction of [Ni6(CO)12]2– with C3Cl6, whereas the related anions, [H6–nNi32C6(CO)36]n− (n = 5 or 6), have been obtained by degradation under carbon monoxide of [Ni38C6(CO)42]6–, or upon thermal treatment at ca. 110 °C of [Ni10C2(CO)16]2– salts. The compound [PPh3Me]6[Ni32C6(CO)36] ·4 MeCN is triclinic, space group P&1macr; (No 2), with a = 15.974(3), b = 17.474(3), c = 18.200(4) Å, α = 61.37(2), β = 69.31(2), γ = 72.35(2)° and Z = 1; final R = 0.033. The structure of [Ni32C6(CO)36]6– has an idealised Oh symmetry and is based on a truncated octahedral Ni32C6 framework, with all edges spanned by bridging carbonyl groups. The six interstitial carbide atoms are lodged in square‐antiprismatic cavities. The overall geometry of the Ni32C6 core is very similar to that found previously in [HNi38C6(CO)42]5–, and shows very close interatomic separations. Both [Ni32C6(CO)36]6– and [H6–nNi38C6(CO)42]n− (n = 5 or 6) display electron‐sink behaviour. Thus, they have been chemically and electrochemically reduced to their corresponding [Ni32C6(CO)36]n− (n = 7–10), [Ni38C6(CO)42]n− (n = 7–9) and [HNi38C6(CO)42]n− (n = 6–8) derivatives, and several of the involved redox changes show features of electrochemical reversibility. In contrast, both [Ni32C6(CO)36]6– and [H6–nNi38C6(CO)42]n− (n = 5 or 6) support only one partially reversible oxidation step. Their different behaviour upon protonation or oxidation is an indirect, but unambiguous, proof of the hydride nature of [HNi32C6(CO)36]5– and [H6–nNi38C6(CO)42]n− (n = 3, 4, or 5), which could not be validated by 1H‐NMR spectroscopy.
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