Sevim Akyüz

An infrared and Raman spectroscopic study of some metal pyridine tetracyanonickelate complexes

Abstract The results of an infrared and Raman spectroscopic study are presented for seven new metal pyridine tetracyanonickelate complexes, M(py) 2 Ni(CN) 4 , M = Mn, Co, Fe, Ni, Cu, Zn and Cd. It is shown that the spectra are consistent with a proposed crystal structure for these complexes derived from X-ray diffraction measurements. The spectra can be clearly distinguished from those of analogous Hofmann-type clathrates with which the nickel complex had been previously confused. The copper complex has spectral features different from the other six compounds and an explanation is proposed in terms of a distortion of the general crystal structure due to the Jahn-Teller effect. Analysis of the single, sharp bands of coordinated pyridine offers a method of resolving some difficulties in earlier assignments of the normal modes of the free base. Several modes of coordinated pyridine have upward shifts in frequency compared to those in the free molecule and the shifts are metal dependent. An explanation, supported by a simple normal coordinate analysis on a model, is provided in terms of coupling with low frequency vibrations, particularly the M-N stretching frequency. Other vibrations of the Ni(CN) 4 group, which coordinates to the metals M to form a two-dimensional coordination polymer, are also metal dependent. It is similarly suggested that coupling with low frequency modes is the principal cause of the upward shifts in frequency.

Host-guest interactions and stability of Hofmann-type benzene and aniline clathrates studied by i.r. spectroscopy

Abstract The results are presented for an i.r. spectroscopic study of thirteen Hofmann-type benzene and aniline clathrates, M (NH 3 ) 2 Ni(CN) 4 , 2G ( M = Mn, Fe, Ni, Cu, Zn, Cd: G = benzene or aniline: and M = Co with aniline). A detailed analysis of the infrared spectra indicates the presence of hydrogen bonding between the ammonia molecules of the host lattices and pi electrons of the aromatic guest molecules. Further hydrogen bonding appears to be present between the amine group of the aniline guest molecules and the cyanide bonds of the host lattices. This bonding may account, in part, for the greater stability of the aniline compared to the benzene clathrates. Analysis of bands in the cyanide stretching region is used to interpret differences in the crystal structures of the clathrates and the nature of the decomposition of the benzene clathrates under grinding or evacuation. The large breadth of the perpendicular compared to the parallel ammonia vibrations indicates that the ammonia molecules are not fixed but undergo rather free internal rotation.

Solid-state vibrational spectroscopy: Part 11. An infrared and raman vibrational spectroscopic study of metal(II) halide aniline complexes

Abstract Infrared (4000−200 cm −1 ) and Raman (3500−50 cm −1 ) spectra are reported for metal(II) halide aniline complexes of the following stoichiometries: (MX 2 an 2 ) (M  Co, Ni or Hg, X  Cl; M  Mn, X  Cl or Br; M  Zn or Cd, X  Cl, Br or I); (MX 2 an 3 ) (M  Mn, X  Cl or Br; M  Ni, X  Cl); (CdCl 2 an) and an assignment is proposed for all the observed bands. Low-temperature (83 K) IR spectra are also reported and it is noted that whilst the aniline ring and CH mode values are virtually insensitive to temperature, the NH 2 rocking and metal-ligand stretching mode values increase with decreasing temperature, whilst the NH 2 stretching mode values decrease with decreasing temperature.

Solid-state vibrational spectroscopy: Part VI. An infrared and raman spectroscopic study of transition metal(II)4-methylpyridine complexes

Infrared (4000–200 cm−1) and Raman (3500–300 cm−1 ) spectra are reported for metal(II) halide and thiocyanate 4-methylpyridine complexes of the following stoichiometries: (MX2(4-Mepy)2) {M = Mn, Co, Cu or Zn, X = Cl or Br; M = Mn, Ni or Zn, X = NCS}; (MX2(4-Mepy)4) {M = Mn, Fe, Co or Ni, X = Cl or Br; M = Mn, Fe, Co, W or Cu, X = NCS}. For a given series of isomorphous complexes there is a correlation between the sum of the differences between the liquid and ligand values of the ν1, ν2, ν3, ν4, ν5, ν6, ν7, ν8, ν9, ν10, ν12, ν13 and ν14 modes of 4-methylpyridine and the strength of the metal-nitrogen bond. Comparison of the shift values of pyridine and 4-methylpyridine complexes supports the suggestion that, unlike the situation in the pyridine complexes, back-donation from the metal to the ligand is unimportant in the 4-methylpyridine complexes.

Adsorption of 2,2′-bipyridyl onto sepiolite, attapulgite and smectite group clay minerals from anatolia: The FT-IR and FT-Raman spectra of surface and intercalated species

The adsorption of 2,2′-bipyridyl by natural sepiolite, attapulgite, hectorite, saponite and natural and ion exchanged (Mn, Fe, Co, Ni, Cu, Zn or Sn) bentonites has been investigated by FT-IR and FT-Raman spectroscopy. Spectroscopic results indicate that most of the adsorbed molecules are coordinated to either exchangeable cations (in the case of smectite group clays) or Lewis acidic centres (in the case of sepiolite and attapulgite) as bidentate ligands. The formation of monoanionic surface species has also been detected, to a relatively small extent. No physisorbed surface species has been observed. XRD patterns and UV-visible spectra of the samples are also recorded for additional information.

Vibrational Spectroscopic Studies of 4,4′-Bipyridyl Metal(II) Tetracyanonickelate Complexes and their Clathrates

The infrared spectra of M(4,4′-bipyridyl)Ni(CN)4 complexes (M=Ni or Cd) and their dioxane, benzene, toluene, aniline andN,N-dimethylaniline clathrates are reported. Additional information regarding the structure of the host lattice is obtained from the Raman spectra of the M=Cd complex. It is shown that the structure of the host lattice consists of infinite polymeric layers of {M-Ni(CN)4}∞ analogous to those of Hofmann type clathrates that have tetragonal symmetry. Bidentate 4,4′-bipyridyl molecules form bridges between the metal atoms {M} in the adjacent {M-Ni(CN)4}∞ layers. It is found that the 4,4′-bipyridyl molecules are centrosymmetric in this structure.

Solid-state vibrational spectroscopy. Part V. An infrared and Raman spectroscopic study of metal(II) halide pyridine complexes

Infrared (200–4 000 cm–1) and Raman (300–3 500 cm–1) spectra are reported for metal(II) halide pyridine complexes of the following stoicheiometries: [MX2(py)2](M = Mn, Fe, Co, Ni, Cu, Zn, Cd, or Hg); [MX2(py)4](M = Fe, Co, or Ni); [MX2(py)2](M = Co, Cu, Cd, or Hg); and [Hg3X6(py)2](X = Cl or Br). Structure–spectra correlations have been found for the dipyridine complexes whose structures are either monomeric tetrahedral {M = Zn or Co; X = Cl or Br; [HgBr2(py)2] and [Cdl2(py)2]}, polymeric octahedral (M = Mn, Ni, or Cd; X = Cl or Br; M = Fe or Co; X = Cl), or distorted polymeric octahedral {M = Cu, X = Cl or Br; and [HgCl2(py)2]}. For a given series of isomorphous complexes there is a correlation between the sum of the difference between the liquid and ligand values of ν2, ν3, ν4, ν5, ν6, ν7, ν8, ν9, ν10, ν17, ν27, and (ν9+ν10) and the strength of the metal–nitrogen bond as measuredbythe ν(M–N) value.

Clathrate and inclusion compounds: Part V1. An infrared and Raman study of the decomposition of the Hofmann aniline clathrates M(NH3)2Ni(CN)4.2C6H5NH2 {M = Cd(II) and Ni(II)}

Abstract The time-dependent changes which are observed in the infrared and Raman spectra of samples of the two Hofmann aniline clathrates M(NH 3 ) 2 Ni(CN) 4 .an 2 {M = Cd(II), Ni(II), an = C 6 H 5 NH 2 } indicate the occurrence of a solid state ligand replacement reaction in which the aniline guest molecule replaces the coordinated ammonia to give Man 2 Ni(CN) 4 as the final product. The rate of replacement is greater for the cadmium than for the nickel clathrate, and for both clathrates evacuation of the sample greatly increases the rate of replacement. The Man 2 Ni(CN) 4 complexes can themselves act as host lattices forming clathrates containing guest molecules such as aniline.

An infrared and Raman spectroscopic study of Td-type 4,4′-bipyridylcadmium(II) tetracyanometallate (II) benzene (1/2) clathrates: Cd(C10H8N2)Cd(CN)4 · 2C6H6 and Cd(C10H8N2)Hg(CN)4 · 2C6H6

Two new benzene clathrates of the form Cd(4,4′-bipyridyl)M(CN)4 · 2C6H6, (M=Cd or Hg) have been prepared in powder form. Their spectral data were compared with those of the corresponding host complexes and found to be consistent with the host structure found in Td-type clathrates.

An infrared and raman spectroscopic study on some 3,5-lutidine metal(II) tetracyanonickelate complexes

Abstract The results of an infrared and Raman spectroscopic study are presented for seven new metal(II) 3,5-lutidine tetracyanonickelate complexes, ML2Ni(CN)4 [where L = 3.5-di-methylpyridine or 3,5-lutidine; M = Mn, Fe, Co, Ni, Cu, Zn or Cd]. Their structure consists of polymeric layers of [MNi(CN)4]∞ with the 3,5-lutidine molecules bound directly to the metal (M). The copper complex has spectral features different from the other six compounds. The effective magnetic moments of the complexes are also given.