Bottom-up synthesis of coordination polymers based on carborane backbones and Cu(2)(CO(2))(4) paddle-wheel: ligand metathesis with metallotecons

Reported here are the bottom-up synthesis and structural analysis as well as the adsorption property investigation of a series of isostructural metal-organic frameworks based on carborane backbones and Cu(2)(CO(2))(4) units. All these compounds are 2D grid structures composed of four component rings. Using linear p-CDC (p-CDCH(2) = 1,12-dihydroxycarbonyl-1,12-dicarba-closo-dodecaborane) as a backbone, only one type of ring formed. However, five types of rings may exist when m-CDCH(2) (m-CDCH(2) = 1,7-dihydroxycarbonyl-1,7-dicarba-closo-dodecaborane) was used due to its varied orientation. Here, the solvent molecules play a key role in the formation of these compounds and the expected five types of rings were obtained. The gas sorption properties of compounds 5' and 8' were studied. These frameworks preferentially adsorb CO(2) over both CH(4) and N(2) due to the coordinatively unsaturated copper ions.     

Synthesis, Structure, and Reactivities of [eta(2)-P(7)M(CO)(4)](3)(-), [eta(2)-HP(7)M(CO)(4)](2)(-), and [eta(2)-RP(7)M(CO)(4)](2)(-) Zintl Ion Complexes Where M = Mo, W

Ethylenediamine (en) solutions of [eta(4)-P(7)M(CO)(3)](3)(-) ions [M = W (1a), Mo (1b)] react under one atmosphere of CO to form microcrystalline yellow powders of [eta(2)-P(7)M(CO)(4)](3)(-) complexes [M = W (4a), Mo (4b)]. Compounds 4 are unstable, losing CO to re-form 1, but are highly nucleophilic and basic. They are protonated with methanol in en solvent giving [eta(2)-HP(7)M(CO)(4)](2)(-) ions (5) and are alkylated with R(4)N(+) salts in en solutions to give [eta(2)-RP(7)M(CO)(4)](2)(-) complexes (6) in good yields (R = alkyl). Compounds 5 and 6 can also be prepared by carbonylations of the [eta(4)-HP(7)M(CO)(3)](2)(-) (3) and [eta(4)-RP(7)M(CO)(3)](2)(-) (2) precursors, respectively. The carbonylations of 1-3 to form 4-6 require a change from eta(4)- to eta(2)-coordination of the P(7) cages in order to maintain 18-electron configurations at the metal centers. Comparative protonation/deprotonation studies show 4 to be more basic than 1. The compounds were characterized by IR and (1)H, (13)C, and (31)P NMR spectroscopic studies and microanalysis where appropriate. The [K(2,2,2-crypt)](+) salts of 5 were characterized by single crystal X-ray diffraction. For 5, the M-P bonds are very long (2.71(1) ?, average). The P(7)(3)(-) cages of 5 are not displaced by dppe. The P(7) cages in 4-6 have nortricyclane-like structures in contrast to the norbornadiene-type geometries observed for 1-3. (31)P NMR spectroscopic studies for 5-6 show C(1) symmetry in solution (seven inequivalent phosphorus nuclei), consistent with the structural studies for 5, and C(s)() symmetry for 4 (five phosphorus nuclei in a 2:2:1:1:1 ratio). Crystallographic data for [K(2,2,2-crypt)](2)[eta(2)-HP(7)W(CO)(4)].en: monoclinic, space group C2/c, a = 23.067(20) ?, b = 12.6931(13) ?, c = 21.433(2) ?, beta = 90.758(7) degrees, V = 6274.9(10) ?(3), Z = 4, R(F) = 0.0573, R(w)(F(2)) = 0.1409. For [K(2,2,2-crypt)](2)[eta(2)-HP(7)Mo(CO)(4)].en: monoclinic, space group C2/c, a = 22.848(2) ?, b = 12.528(2) ?, c = 21.460(2) ?, beta = 91.412(12) degrees, V = 6140.9(12) ?(3), Z = 4, R(F) = 0.0681, R(w)(F(2)) = 0.1399.     

Insertion of a bis(phosphine)platinum group into the S-S bond of Mn(2)(CO)(7)(mu-S(2))

The reaction of Mn(2)(CO)(7)(mu-S(2)), 1, with Pt(PPh(3))(2)(PhC(2)Ph) yielded the new complex, Mn(2)(CO)(6)Pt(PPh(3))(2)(mu(3)-S)(2), 3, by loss of CO and insertion of a Pt(PPh(3))(2) group into the S-S bond of 1. Complex 3 was characterized crystallographically and was found to consist of an open Mn(2)Pt cluster with one Mn-Mn bond, 2.8154(14) A, one Mn-Pt bond, 2.9109(10) A, and two triply bridging sulfido ligands. Compound 3 reacts with CO to form adduct Mn(2)(CO)(6)(mu-CO)Pt(PPh(3))(2)(mu(3)-S)(2), 4. Compound 4 also contains an open Mn(2)Pt cluster with two triply bridging sulfido ligands but has only one metal-metal bond, Mn-Mn = 2.638(2) A. Under nitrogen, compound 4 readily loses CO and reverts back to 3.     

Crystal structure and spectroscopic properties of Na(2)K(6)(VO)(2)(SO(4))(7)

Red-brown crystals of a new mixed alkali oxo sulfato vanadium(V) compound Na(2)K(6)(VO)(2)(SO(4))(7), suitable for X-ray determination, have been obtained from the catalytically important binary molten salt system M(2)S(2)O(7)-V(2)O(5) (M = 80% K and 20% Na). By slow cooling of a mixture with the mole fraction X(V(2)O(5)) = 0.24 from 325 degrees C, i.e., just below the liquidus temperature, to the solidus temperature of around 300 degrees C, a dark reddish amorphous phase was obtained containing crystals of the earlier described V(V)-V(IV) mixed valence compound K(6)(VO)(4)(SO(4))(8) and Na(2)K(6)(VO)(2)(SO(4))(7) described here. This compound crystallizes in the tetragonal space group P4(3)2(1)2 (No. 96) with a = 9.540(3) A, c = 29.551(5) A at 20 degrees C and Z = 4. It contains a distorted VO(6) octahedron with a short V-O bond of 1.552(6) A, a long one of 2.276(5) A trans to this, and four equatorial V-O bonds in the range 1.881(6)-1.960(6) A. The deformation of the VO(6) octahedron is less pronounced compared to that of the known oxo sulfato V(V) compounds. Each VO(3+) group is coordinated to five sulfate groups of which two are unidentately coordinated and three are bidentate bridging to neighboring VO(3+) groups. The length of the S-O bonds in the S-O-V bridges of the two unidentately coordinated sulfato groups are 1.551(6) A and 1.568(6) A, respectively, which are unusually long compared to our earlier measurements of sulfate groups in other V(III), V(IV), and V(V) compounds.     

Characterization and structure of OsH(OH)(CO)(PtBu2Me)2

A synthesis of the title compound by hydrolysis of OsH(C₆H₅)(CO)(P^tBu₂Me)₂ has the advantage that the product shows ¹H NMR spectra free of the influence of hydrogen bonding to water impurity. In the solid state, the hydroxyl group interacts weakly with that of a neighbor. The Os–OH bond is rapidly split by H₂, to give H₂O and Os(H)₂(H₂)(CO)(P^tBu₂Me)₂.     

Dynamic behavior of the diphosphine ligand in H4Ru4(CO)10(dppe) revisited: kinetic data supporting a nondissociative isomerization of the dppe ligand

The kinetics for the bridge-to-chelate isomerization of the dppe ligand in H4Ru4(CO)10(dppe) have been investigated by UV-vis and NMR spectroscopies over the temperature range of 308-328 K. The isomerization of the ligand-bridged cluster 1,2-H4Ru4(CO)10(dppe) (1-br) was found to be reversible by 31P NMR spectroscopy, affording a K(eq) = 15.7 at 323 K in favor of the chelating dppe isomer 1-ch. The forward (k1) and reverse (k(-1)) first-order rate constants for the reaction have been measured in different solvents and in the presence of ligand-trapping agents (CO and PPh3). On the basis of the activation parameters and reaction rates that are unaffected by added CO and PPh3, a sequence involving the nondissociative migration of a phosphine moiety and two CO groups between basal ruthenium centers is proposed and discussed.     

Models of the iron-only hydrogenase: structural studies of chelating diphosphine complexes [Fe2(CO)4(micro-pdt)(kappa2P,P'-diphosphine)

Six chelating diphosphine complexes, [Fe2(CO)4(micro-pdt)(kappa2P,P'-diphosphine)], have been crystallographically characterised allowing differences between basal-apical and dibasal conformations to be analysed.     

Reactions of thioethers with Mn(2)(CO)(7)(mu-S(2)) proceed with CO displacement and insertion of the sulfur atom into the Mn-Mn bond

The reaction of Mn(2)(CO)(7)(mu-S(2)) (2) with SMe(2) yielded the new complexes Mn(2)(CO)(6)(mu-S(2))(mu-SMe(2)) (3) and Mn(4)(CO)(14)(SMe(2))(mu(3)-S(2))(mu(4)-S(2)) (4) in 18 and 41% yields, respectively. The reaction of 2 with the cyclic thioether thietane SCH(2)CH(2)CH(2) yielded the new complexes Mn(2)(CO)(6)(mu-S(2))(mu-SCH(2)CH(2)CH(2)) (5) and Mn(4)(CO)(14)(SCH(2)CH(2)CH(2))(mu(3)-S(2))(mu(4)-S(2)) (6) in 12 and 52% yields, respectively, and the reaction of 2 with 1,4,9-trithiacyclododecane (12S3) yielded Mn(2)(CO)(6)(mu-12S3)(mu-S(2)) (7) and Mn(4)(CO)(14)(12S3)(mu(3)-S(2))(mu(4)-S(2)) (8) in 8 and 24% yields, respectively. Compounds 3 and 5-7 were characterized crystallographically. Compounds 3, 5, and 7 have similar structures in which the thioether ligand has replaced the bridging carbonyl ligand of 2 and its sulfur atom has been inserted into the manganese-manganese bond. The two manganese atoms are not mutually bonded, and two Mn(CO)(3) groups are held together through the bridging disulfido ligand and the bridging sulfur atom of the thioether ligand. Compound 6 contains a Mn(4)(mu(3)-S(2))(mu(4)-S(2)) moiety without metal-metal bonds. On the basis of spectroscopic data, compounds 4 and 8 are believed to have similar structures.     

Synthesis and crystal structures of (fulvalene)W(2)(SH)(2)(CO)(6), (fulvalene)W(2)(mu-S(2))(CO)(6), and (fulvalene)W(2)(mu-S)(CO)(6): low valent tungsten carbonyl sulfide and disulfide complexes stabilized by the bridging fulvalene ligand

Reaction of FvW(2)(H)(2)(CO)(6) with 2/8S(8) in THF results in rapid and quantitative formation of FvW(2)(SH)(2)(CO)(6). The crystal structure of this complex is reported and shows that the two tungsten-hydrosulfide groups are on opposite faces of the fulvalene ligand in an anti configuration. Nevertheless, treatment of FvW(2)(SH)(2)(CO)(6) (1) with PhN[double bond]NPh produces FvW(2)(mu-S(2))(CO)(6) (2) and Ph(H)NN(H)Ph. The crystal structure of the bridging disulfide, which cocrystallizes with 1 in a 2:1 ratio, is also described. Exposure of 2 equiv of *CrCp*(CO)(3) to 1 effects similar H atom transfers yielding 2 HCrCp*(CO)(3) and 2. Attempts to obtain crystals of the latter from solutions derived from this reaction mixture furnished a third product, FvW(2)(mu-S)(CO)(6) (3), which was analyzed crystallographically. The enthalpy of sulfur atom insertion into FvW(2)(H)(2)(CO)(6), yielding 1, has been measured by solution calorimetry.     

Investigation of mixed divalent cation phosphates: synthesis and X-ray powder structure determination of CdBa2(P2O7)(HPO4)

Hydrothermal synthesis, characterization by X-ray diffraction, IR absorption, TGA and ab-initio crystal structure determination are reported for a new phosphate CdBa₂(P₂O₇)(HPO₄). It crystallizes in a monoclinic cell (space group Im, No. 8, Z=2) with a=11.9022(1) Å, b=5.5530(1) Å, c=7.3401(1) Å, β=90.091(1)°. The X-ray powder diffraction pattern was fitted by the Rietveld method technique with reliability R_Bragg=0.037. Hydrogen atoms could not be located. The crystal structure of CdBa₂(P₂O₇)(HPO₄) is built up from P₂O₇ diphosphate groups sharing four oxygen atoms with two CdO₆ trigonal prisms. Each CdO₆ trigonal prism shares one edge with the HPO₄ unit. Such an arrangement builds up isolated infinite chains CdP₃O₁₁ running along the b axis. Ba²⁺ ions are inserted between these chains in the (b,c) plane.     

The effects of ligand variation on enantioselective hydrogenation catalysed by RuH2(diphosphine)(diamine) complexes

Density functional theory calculations have been used to investigate the hydrogenation of acetophenone (ACP) catalysed by the RuH(2)(diphosphine)(diamine) complexes with emphasis on the effect of the structure of the diphosphine and diamine ligands on the enantioselectivity. The computed reaction coordinate diagrams of RuH(2)(diphosphine)[(S,S)-DPEN] catalysed reactions with different (S)-diphosphine ligands (XylBINAP, TolBINAP, and BINAP) show that the presence of two methyl groups in the meta position is critical to obtaining a high difference in activation energy for the reaction pathways associated with the (R)- and (S)-alcohols, and consequently high enantioselectivity. The effect of the diamine structure while keeping the TolBINAP and XylBINAP fixed has also been analysed. To enhance the enantioselectivity of the TolBINAP system, the addition of two methyl groups and the removal of a phenyl group of the diamine (DMAPEN) offer the necessary steric interactions. We conclude by reporting a correlation between the enantiomeric excess and the difference in the computed activation energies of the two most favourable (S) and (R) reaction pathways, which shows that the computational procedure adopted could be used to predict the enantiomeric excess of ketone hydrogenation reactions catalysed by the Noyori-type catalysts, and assist in the choice of ligand when optimising the enantiomeric excess.     

Synthesis and diphosphine ligand fluxionality in Os3(CO)10(bmi): Kinetic evidence for nondissociative diphosphine isomerization and X-ray crystal structure of 1,1-Os3(CO)10(bmi)

The triosmium cluster 1,2-Os₃(CO)₁₀(MeCN)₂ reacts rapidly with the diphosphine ligand 2,3-bis(diphenylphosphino)-N-p-tolylmaleimide (bmi) at room temperature to give bmi-bridged cluster 1,2-Os₃(CO)₁₀(bmi) (2b) as the major product, along with the chelating isomer 1,1-Os₃(CO)₁₀(bmi) (2c) and the hydride-bridged cluster HOs₃(CO)₉[μ-(PPh₂)CC{PPh(C₆H₄)}C(O)N(tolyl-p)C(O)] (3) as minor by-products. All three cluster compounds have been isolated and fully characterized in solution by IR and NMR spectroscopies (¹H and ³¹P), and X-ray crystallography in the case of 2c. Cluster 2b is unstable and readily isomerizes to 2c in quantitative yield on mild heating. The kinetics for the conversion of 2b → 2c have been measured over the temperature range of 318-348 K in toluene solution, and based on the observed activation parameters a nondissociative isomerization process that proceeds via a transient μ₂-bridged phosphine moiety is presented. Near-UV photolysis of cluster 2c at room temperature affords HOs₃(CO)₉[μ-(PPh₂)CC{PPh(C₆H₄)}C(O)N(tolyl-p)C(O)] (3) with a quantum yield of 0.017. The reactivity of clusters 2b, 2c, and 3 is discussed with respect to related diphosphine-substituted Os₃(CO)₁₀(P-P) clusters prepared by our groups.     

Synthesis and electrochemistry of new Rh-centered and conjuncto rhodium carbonyl clusters. X-ray structure of [NEt(4)](3)[Rh(15)(CO)(27)], [NEt(4)](3)[Rh(15)(CO)(25)(MeCN)(2)] x 2MeCN, and [NEt(4)](3)[Rh(17)(CO)(37)

A reinvestigation of the redox chemistry of [Rh7(CO)16]3- resulted in the finding of new alternative syntheses for a series of previously reported Rh-centered carbonyl clusters, i.e., [H4-nRh14(CO)25]n- (n = 3 and 4) and [Rh17(CO)30]3-, as well as new species such as a different isomer of [Rh15(CO)27]3-, the carbonyl-substituted [Rh15(CO)25(MeCN)2]3-, and the conjuncto [Rh17(CO)37]3- clusters. All of the above clusters are suggested to derive from oxidation of [Rh7(CO)16]3- with H+, arising from dissociation either of [M(H2O)n]2+ aquo complexes or nonoxidizing acids. The nature of the previously reported species has been confirmed by IR, electrospray ionization mass spectrometry, and complete X-ray diffraction studies. Only the molecular structures of the new clusters are reported in some details. The ready conversion of [Rh7(CO)16]3- in [HRh14(CO)25]3- upon oxidation has been confirmed by electrochemical techniques. In addition, electrochemical studies point out that the close-packed [H3Rh13(CO)24]2- dianion undergoes a reversible monoelectronic reduction followed by an irreversible reduction. The irreversibility of the second reduction is probably a consequence of H2 elimination from a purported [H3Rh13(CO)24]4- species. Conversely, the body-centered-cubic [HRh14(CO)25]3- and [Rh15(CO)27]3- trianions display several well-defined redox changes with features of electrochemical reversibility, even at low scan rate. The major conclusion of this work is that mild experimental conditions and a tailored oxidizing reagent may enable more selective conversion of [Rh7(CO)16]3- into a higher-nuclearity rhodium carbonyl cluster. It is also shown that isonuclear Rh clusters may display isomeric metal frameworks [i.e., [Rh15(CO)27]3-], as well as almost identical metal frames stabilized by a different number of carbonyl groups [i.e., [Rh15(CO)27]3- and [Rh15(CO)30]3-]. Other isonuclear Rh clusters stabilized by a different number of CO ligands more expectedly exhibit completely different metal geometries [i.e., [Rh17(CO)30]3- and [Rh17(CO)37]3-]. The first pair of isonuclear and isoskeletal clusters is particularly astonishing in that [Rh15(CO)30]3- features six valence electrons more than [Rh15(CO)27]3-. Finally, the electrochemical studies seem to suggest that interstitial Rh atoms are less effective than Ni and Pt interstitial atoms in promoting redox properties and inducing molecular capacitor behavior in carbonyl clusters.     

Synthesis and structural and magnetic characterization of {[(phen)(2)Ni](2)(micro-P(2)O(7))} . 27H(2)O and {[(phen)(2)Mn](2)(micro-P(2)O(7))} . 13H(2)O: rare examples of coordination complexes with the pyrophosphate ligand

The reaction in water of M(II) [M = Ni or Mn] with 1,10-phenanthroline (phen) and sodium pyrophosphate (Na4P2O7) in a 2:4:1 stoichiometry resulted in the crystallization of dinuclear complexes featuring the heretofore rare bridging pyrophosphate. Single-crystal X-ray diffraction studies revealed the complexes to be {[(phen)2Ni]2(micro-P2O7)} . 27H2O (1) and {[(phen)2Mn]2(micro-P2O7)} . 13H2O (2) where the asymmetric M(phen)2 units are bridged by bis-bidentate pyrophosphate, each metal ion exhibiting a distorted octahedral geometry. The bridging pyrophosphate places adjacent metal centers at 5.031 A in 1 and 4.700 A in 2, and its conformation also gives rise to an intramolecular pi-pi interaction between two adjacent phen ligands. Intermolecular pi-pi interactions between phen ligands from adjacent dinuclear complexes create an ornate 3D network in 1, whereas a 2D sheet results in 2. The hydrophilic nature of the pyrophosphate ligand leads to heavy hydration with the potential solvent-accessible area for 1 and 2 accounting for 45.7% and 26.4% of their unit cell volumes, respectively. Variable-temperature magnetic susceptibility measurements on polycrystalline samples of 1 and 2 revealed net weak intramolecular antiferromagnetic coupling between metal centers in both compounds with J = -3.77 cm(-1) in 1 and J = -0.88 cm(-1) in 2, the Hamiltonian being defined as H = -JSA.SB. The ability of the bis-bidentate pyrophosphate to mediate magnetic interactions between divalent first row transition metal ions is discussed bearing in mind the number and nature of the interacting magnetic orbitals.     

Crystal structure and ionic conductivity of AgCr2(PO4)(P2O7)

Single crystals of a new phosphate AgCr₂(PO₄)(P₂O₇) have been prepared by the flux method and its structural and the infrared spectrum have been investigated. This compound crystallizes in the monoclinic system with the space group C2/c and the parameters are, a = 11.493 (3) Å, b = 8.486 (3) Å, c = 8.791 (2) Å, β = 114.56 (2)°, V = 779.8 (3) ųand Z = 4. Its structure consists of CrO₆ octahedra sharing corners with P₂O₇ units to form undulating chains extending infinitely along the [110] direction. These chains are connected by the phosphate tetrahedra giving rise to a 3D framework with six-sided tunnels parallel to the [101] direction, where the Ag⁺ ions are located. The infrared spectrum of this compound was interpreted on the basis of P₂O₇^4? and PO₄^3? vibrations. The appearance of ν_sP–O–P in the spectrum suggests a bent P–O–P bridge for the P₂O₇^4? ions in the compound, which is in agreement with the X-ray data. The electrical measurements allow us to obtain the activation energy of (1.36 eV) and the conductivity measurements suggest that the charge carriers through the structure are the silver captions.     

Anion-directed crystallization of coordination polymers: syntheses and characterization of Cu(4)(2-pzc)(4)(H(2)O)(8)(Mo(8)O(26)).2H(2)O and Cu(3)(2-pzc)(4)(H(2)O)(2)(V(10)O(28)H(4)).6.5H(2)O (2-pzc = 2-pyrazinecarboxylate)

Two new copper 2-pyrazinecarboxylate (2-pzc) coordination polymers incorporating [Mo(8)O(26)](4-) and [V(10)O(28)H(4)](2-) anions were synthesized and structurally characterized: Cu(4)(2-pzc)(4))(H(2)O)(8)(Mo(8)O(26)).2H(2)O (1) and Cu(3)(2-pzc)(4)(H(2)O)(2)(V(10)O(28)H(4)).6.5H(2)O (2). Crystal data: 1, monoclinic, space group P2(1)/n, a = 11.1547(5) A, b = 13.4149(6) A, c = 15.9633(7) A, beta = 90.816(1) degrees; 2, triclinic, space group P1, a = 10.5896(10) A, b = 10.7921(10) A, c = 13.5168(13) A, alpha = 104.689(2) degrees, beta = 99.103(2) degrees, gamma = 113.419(2) degrees. Compound 1 contains [Cu(2-pzc)(H(2)O)(2)] chains charge-balanced by [Mo(8)O(26)](4-) anions. In compound 2, layers of [Cu(3)(2-pzc)(4)(H(2)O)(2)] form cavities that are filled with [V(10)O(28)H(4)](2-) anions. The magnetic properties of both compounds are described.     

Crystal structure of (C2H7N4O)2[(UO2)2)(OH)2(C2O4)(CHO2)2]

An X-ray diffraction study of the single crystals of (C₂H₇N₄O)₂[(UO₂)₂(OH)₂(C₂O₄)(CHO₂)₂] was carried out. The compound crystallizes in the triclinic system, space group $P\bar 1$ , Z = 2, a = 5.5621(8) Å, b = 8.1489(10) Å, c = 11.8757(16) Å, α = 88.866(7)°, β = 82.204(6)°, γ = 87.378(6)°, V = 532.7(1) ų, ρ_calcd = 2.988 g/cm³. The main structural units in the crystal are the [(UO₂)₂(OH)₂(C₂O₄)(CHO₂)₂)]^2? chains corresponding to the crystal chemical group A₂M ₂ ² K⁰²M ₂ ¹ (A = UO ₂ ²⁺ , M² = OH^?, K⁰² = C₂O ₄ ^2? , M¹ = CHO ₂ ^? ) of uranyl complexes. The chains are united into a three-dimensional framework through the electrostatic interaction and hydrogen bonds involving uranyl, oxalate, and hydroxyl groups, formate ions, and 1-carbamoylguanidinium cations.     

Experimental Raman spectra of dilute and laser-light-sensitive [Rh(4)(CO)(9)(mu-CO)(3)] and [(mu(4)-eta(2)-3-hexyne)Rh(4)(CO)(8)(mu-CO)(2)]. Comparison with theoretically predicted spectra

The reaction of [Rh(4)(CO)(9)(mu-CO)(3)] with 3-hexyne to form the butterfly cluster [(mu(4)-eta(2)-3-hexyne)Rh(4)(CO)(8)(mu-CO)(2)] was monitored viain-situ Raman spectroscopy using an NIR laser source, at room temperature and under atmospheric argon using n-hexane as solvent. The collected raw spectra were deconvoluted using band-target entropy minimization (BTEM). The pure component mid-Raman spectra of the [Rh(4)(CO)(9)(mu-CO)(3)] and the butterfly cluster [(mu(4)-eta(2)-3-hexyne)Rh(4)(CO)(8)(mu-CO)(2)], were reconstructed with a high signal-to-noise ratio. Full geometric optimization and Raman vibrational prediction were carried out using DFT. The experimental and predicted Raman spectra were in good agreement. In particular, the far-Raman vibrational modes in the region 100-280 cm(-1) provided characterization of the metal-metal bonds and direct confirmation of the structural integrity of the polynuclear frameworks in solution.