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The infrared photodissociation spectroscopy of mass-selectedmononucleariron carbonyl anions Fe(CO)n–(n= 2–8) were studied in the carbonyl stretchingfrequency region. The FeCO–anion does not fragmentwhen excited with infrared light. Only a single IR active band wasobserved for the Fe(CO)2–and Fe(CO)3–anions, consistent with theoretical predictionsthat these complexes have linear D∞hand planar D3hsymmetry, respectively. The Fe(CO)4–anion is the most intense peak in the mass spectra and was characterizedto have a completed coordination sphere with high stability. Anionclusters larger than n= 4 were determined to involvea Fe(CO)4–core anion that is progressivelysolvated by external CO molecules. Three CO stretching vibrationalfundamentals were observed for the Fe(CO)4–core anion, indicating that the Fe(CO)4–anion has a C3vstructure.All the carbonyl stretching frequencies of the Fe(CO)n–anion complexes are red-shiftedwith respect to those of the corresponding neutrals. [ABSTRACT FROM AUTHOR]

Heteronuclear arsenic-iron carbonyl cluster anions As m Fe(CO) n - ( m , n = 2, 3) have been generated in the gas phase and investigated by mass-selected infrared photodissociation spectroscopy and density functional theory calculations at the B3LYP/BP86/TPSS levels. All the As m Fe(CO) n - ( m , n = 2, 3) cluster anions are determined to contain Fe(CO) n - fragments, which can be regarded as being formed by replacing one arsenic atom of the arsenic clusters As m +1 with the Fe(CO) n - group. Bonding analyses indicated that each As 2 Fe(CO) n - ( n = 2, 3) cluster anion involves two Fe-As single bonds and one As-As double bond. Each As 3 Fe(CO) n - ( n = 2, 3) cluster anion has three Fe-As single bonds and three As-As single bonds. The Fe(CO) 3 - group with a 15-electron configuration is valence isoelectronic to the As atom and can serve as a building block for forming heteronuclear arsenic-iron carbonyl clusters.

Mass-selected heteronuclear iron-copper carbonyl cluster anions CuFe(CO)n(-) (n = 4-7) are studied by infrared photodissociation spectroscopy in the carbonyl stretching frequency region in the gas phase. The cluster anions are produced via a laser vaporization supersonic cluster ion source. Their geometric structures are determined by comparison of the experimental spectra with those calculated by density functional theory. The experimentally observed CuFe(CO)n(-) (n = 4-7) cluster anions are characterized to have (OC)4Fe-Cu(CO)n-4 structures, each involving a C3v symmetry Fe(CO)4(-) building block. Bonding analysis indicates that the Fe-Cu bond in the CuFe(CO)n(-) (n = 4-7) cluster anions is a σ type single bond with the iron center possessing the most favored 18-electron configuration. The results provide important new insight into the structure and bonding of hetronuclear transition metal carbonyl cluster anions.

Infrared spectra of mass-selected homoleptic cobalt carbonyl cluster cations including dinuclear Co2(CO)8(+) and Co2(CO)9(+), trinuclear Co3(CO)10(+) and Co3(CO)11(+), as well as tetranuclear Co4(CO)12(+) are measured via infrared photodissociation spectroscopy in the carbonyl stretching frequency region. The geometric structures of these complexes are determined by comparison of the experimental spectra with those calculated by density functional theory. The Co2(CO)8(+) cation is characterized to have a Co-Co bonded structure with Cs symmetry involving a bridging CO ligand. The Co2(CO)9(+) cation is determined to be a mixture of the CO-tagged Co2(CO)8(+)-CO complex and the Co(CO)5(+)-Co(CO)4 ion-molecular complex. The Co3(CO)10(+) cation is the coordination-saturated trinuclear cluster, which is characterized to have a triangle Co3 core with C2 symmetry involving two edge-bridging and eight terminal CO ligands. The Co3(CO)11(+) cation is a weakly bound complex involving a Co3(CO)10(+) core ion. The Co4(CO)12(+) cluster cation is deduced to have a tetrahedral Co4(+) core structure with three edge-bridging and nine terminal carbonyls.

Infrared spectra of mass-selected homoleptic copper carbonyl cluster cations including dinuclear Cu2(CO)6(+) and Cu2(CO)7(+), trinuclear Cu3(CO)7(+), Cu3(CO)8(+), and Cu3(CO)9(+), and tetranuclear Cu4(CO)8(+) are measured via infrared photodissociation spectroscopy in the carbonyl stretching frequency region. The structures are established by comparison of the experimental spectra with simulated spectra derived from density functional calculations. The Cu2(CO)6(+) cation is characterized to have an unbridged D3d structure with a Cu-Cu half bond. The Cu2(CO)7(+) cation is determined to be a weakly bound complex involving a Cu2(CO)6(+) core ion. The trinuclear Cu3(CO)7(+) and Cu3(CO)8(+) cluster cations are determined to have triangle Cu3 core structures with C2 symmetry involving two Cu(CO)3 groups and one Cu(CO)x group (x = 1 or 2). In contrast, the trinuclear Cu3(CO)9(+) cluster cation is determined to have an open chain-like (OC)3Cu-Cu(CO)3-Cu(CO)3 structure. The tetranuclear Cu4(CO)8(+) cluster cation is characterized to have a tetrahedral Cu4(+) core structure with all carbonyl groups terminally bonded.

The photoelectron images of Ag(-)(H(2)O)(x) (x=1,2) and AgOH(-)(H(2)O)(y) (y=0-4) are reported. The Ag(-)(H(2)O)(1,2) anionic complexes have similar characteristics to the other two coinage metal-water complexes that can be characterized as metal atomic anion solvated by water molecules with the electron mainly localized on the metal. The vibrationally well-resolved photoelectron spectrum allows the adiabatic detachment energy (ADE) and vertical detachment energy (VDE) of AgOH(-) to be determined as 1.18(2) and 1.24(2) eV, respectively. The AgOH(-) anion interacts more strongly with water molecules than the Ag(-) anion. The photoelectron spectra of Ag(-)(H(2)O)(x) and AgOH(-)(H(2)O)(y) show a gradual increase in ADE and VDE with increasing x and y due to the solvent stabilization., (© 2011 American Chemical Society)

A photoelectron spectroscopy investigation of the fluorofullerene anions C(60)F(n)(-) (n = 17, 33, 35, 43, 45, 47) and the doubly charged anions C(60)F(34)(2-) and C(60)F(46)(2-) is reported. The first electron affinities for the corresponding neutral molecules, C(60)F(n), were directly measured and were found to increase as n increased, reaching the extremely high value of 5.66 +/- 0.10 eV for C(60)F(47). Density functional calculations suggest that the experimentally observed species C(60)F(17)(-), C(60)F(35)(-), and C(60)F(47)(-) were each formed by reductive defluorination of the parent fluorofullerene, C(3v)-C(60)F(18), C(60)F(36) (a mixture of isomers), and D(3)-C(60)F(48), respectively, without rearrangement of the remaining fluorine atoms. The DFT-predicted stability of C(60)F(47)(-) was verified by its generation by chemical reduction from D(3)-C(60)F(48) in chloroform solution at 25 degrees C and its characterization by mass spectrometry and (19)F NMR spectroscopy. Further reductive defluorination of C(60)F(47)(-) in solution resulted in the selective generation of a new fluorofullerene, D(2)-C(60)F(44), which was also characterized by mass spectrometry and (19)F NMR spectroscopy.