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Cyanide has been investigated as a potential ligand-directed probe of the coordination chemistry of Cu(II) and Cu(I) active sites via vibrational spectroscopic studies of CN - coordinated to the metal centers in non-blue copper proteins. Native superoxide dismutase (SOD) was found to bind one CN - that had IR and Raman frequencies at 2137 cm -1

The copper complex [Cu 2 (XYL-O-)(OH)] 2+ , where XYL=m-xylene connected to twobis[2-(2-pyridyl)ethyl]amine ligands, serves as a potential model for the dinuclear copper sites in hemocyanin, tyrosinase, and the multicopper oxidases. Resonance Raman (RR) and infrared spectra of the complex reveal a v s (Cu-OH-Cu) mode at 465 cm -1 and a v as (Cu-OR-Cu) mode at 603 cm -1 . These represent the first such modes to be defitively identified by isotopic shifts and polarization behavior

We report herein the resonance Raman, electronic absorption, and Fourier transform intrared (IR) spectra of tetracoordinate Cu II and Ni II complexes of cis- and trans-octaethylchlorin 23 (Figure 1). Both the stereochemistry at the pyrroline ring and the macrocyclic conformation (planar vs S 4 -ruffled) are clearly shown to influence the spectral properties of the M(OEC) complexes

To evaluate the effects of sequential pyrrole ring reduction, we have examined the vibrational spectra of tetracoordinate Zn(II) complexes of meso-tetraphenylporphyrin [Zn(TPP)], meso-tetraphenylchlorin [Zn(TPC)], and meso-tetraphenylisobacteriochlorin [Zn(TPiBC)]. The phenyl substituents of these macrocycles fall into distinct symmetry classes; for Zn(TPP), all four phenyl groups are equivalent; for Zn(TPC), the phenyl groups are of two different types; and for Zn(TPiBC), there are three types of phenyl substituent

The excited state of Ir 2 (TMB) 4 2+ (TMB=2,5-dusocyano-2,5-dimethylhexane) reacts with hydrogen atom donors to give Ir 2 (TMB) 4 H 2 2+ (Ir 2 H 2 ). This d 7 -d 7 dihydride has been isolated as a tetraphenylborate salt: crystallizes in the monoclinic system, space group P2 1 /c

Reduction of Zr(O-2,6-Me(2)C(6)H(3))Cl(2)[N(SiMe(2)CH(2)PPr(i)(2))(2)] with sodium amalgam under dinitrogen yields the dinuclear zirconium dinitrogen complex {[(Pr(i)(2)PCH(2)SiMe(2))(2)N]Zr(O-2,6-Me(2)C(6)H(3))}(2)(mgr;-eta(2):eta(2)-N(2)). Solid state structural analysis shows that the dinitrogen unit is bound in a side-on mode of coordination with the N-N bond distance at 1.528(7) Å; resonance Raman spectra show a band at 751 cm(-)(1) for nu(N-N), which is consistent with this very long bond. In addition, the N(2) ligand is hinged slightly so that the Zr(2)(mgr;-eta(2):eta(2)-N(2)) core adopts a flattened butterfly shape rather than a completely planar core as found in other related systems. Other Zr(IV) precursors of the general formula ZrCl(2)X[N(SiMe(2)CH(2)PPr(i)(2))(2)] (X = OBu(t), OCHPh(2), NPh(2)) either decompose upon reduction under N(2) or produce mixtures of products.

Resonance Raman spectra of the complex of Fe/sup III/-ethylenediaminetetraacetate with hydrogen peroxide have been obtained in the region of the peroxidic O-O stretching vibration that occurs at 815 cm/sup /minus/1/ in frozen solution. When the complex was prepared from nearly neat, mixed-isotope hydrogen peroxide, H/sub 2//sup 16/O/sup 18/O, a single O-O vibration was observed at 794 cm/sup /minus/1/. This observation establishes that the two oxygen atoms of the bound peroxide are equivalent and that the peroxide is ligated in an /eta//sup 2/ side-on configuration in this mononuclear complex. The absence of any shift in /nu/(O-O) when the complex was prepared in D/sub 2/O solvent provides further support for the side-on Fe(O-O) geometry and rules out the alternative /eta//sup 1/ end-on Fe-OOH configuration. In contrast, /nu/(O-O) of free hydrogen peroxide in the frozen state occurs at 877 cm/sup /minus/1/ in H/sub 2/O and 879 cm/sup /minus/1/ in D/sub 2/O. The 2-cm/sup /minus/1/ upshift in D/sub 2/O is similar to that observed previously with oxyhemerythrin and appears to be characteristic of a hydrogen-bonded or protonated peroxide species. 37 references, 4 figures, 1 table.

Cristallisation dans le groupe P1. Affinement jusqu'a R=0,0895. Le cation dimere montre une longueur de liaison Fe−O normale, 1,785 A et un angle Fe−O−Fe de 155,1°. Presentation detaillee des spectres IR et Raman pour l'etude de la vibration Fe−O−Fe