Carola Engelter

Infrared spectra of o-toluidine and m-toluidine complexes of Co(II), Ni(II), Cu(II) and Zn(II) halides

Abstract The infrared spectra of eighteen metal complexes of empirical formula [ML 2 X 2 ] (M = Co, Ni, Cu or Zn; L = o − or m -toluidine; X = Cl, Br or I) have been determined over the range 4000-150 cm −1 . Assignments of the internal vibrations of the amino group are based on the band shifts induced by 15 N-labelling of the nitrogen donors. Bands within the range 400–600 cm −1 are assigned to the metal-nitrogen stretching frequency ( v M-N) on the grounds of their sensitivity to 15 N-labelling and metal ion substitution and their absence of sensitivity to halide substitution. Bands within the range 350–150 cm −1 are assigned to the metal-halogen stretching frequency ( v M-X) on the basis of their sensitivity to halide and metal ion substitution and their insensitivity to 15 N-labelling. Structural aspects of the spectra are discussed and the present assignments are compared with those previously reported.

Spectra-structure correlations from the infrared spectra of some transition metal complexes of 8-hydroxyquinoline

Abstract The IR spectra of twenty-one transition metal complexes of 8-hydroxyquinoline over the range 700-50 cm −1 are discussed in relation to their known or inferred structures. The complexes are of three types: (a) the bis (aquo) complexes of the 3 d metal(II) ions trans -[M(ox) 2 (H 2 O) 2 ] (M = Mn, Fe, Co, Ni, Cu, Zn); (b) the corresponding anhydrous complexes, [M(ox) 2 ] (M = Mn, Co, Ni, Cu, Zn); and (c) the complexes of the metal(III) ions, [M(ox) 3 ] (M = Sc, V, Cr, Mn, Fe, Co, Ga). 8-Hydroxyquinoline- d 7 has been synthesized and used to assist in the metal-ligand assignments which are further based on 64,68 Zn labelling of the bis (aquo) zinc complex and on the effects of metal ion substitution in relation to expectations based on crystal field theory. The effects of Jahn-Teller distortion on the spectra of the complexes of Cu(II) and Mn(III) are discussed. The spectra of the bis (aquo) adducts support the previously proposed trans -octahedral structure. The spectra of the anhydrous complexes are consistent with tetrahedral Mn, Ni and Zn but suggest that the Co complex has polymeric octahedral coordination rather than the previously-proposed tetrahedral structure. The six-coordinate α-Cu complex and five-coordinate β-Cu complex exhibit distinctive differences in their spectra which support the elongated axial Cu-O bonds observed in crystal structure determinations. The spectra of the metal(III) tris (oxinates) are consistent with the facial ( cis-cis ) coordination previously proposed. The spectra of these complexes are discussed in relation to bonding considerations based on crystal field theory.

Infrared spectra of bis(aniline) and bis (p-toluidine) metal(II) isothiocyanate complexes

Abstract The infrared spectra of eight complexes of general formula [ML2(NCS)2] (M = Co, Ni, Cu, Zn; L = aniline or p-toluidine) have been determined over the range 4000–4150 cm−1. Colour, magnetic moments and IR spectra are consistent with polymeric octahedral coordination in the Co(II) and Ni(II) complexes and polymeric tetragonal coordination in the Cu(II) complexes, while the Zn(II) complexes are assigned polymeric octahedral (L = aniline) and tetrahedral (L = p-toluidine) structure on the basis of their IR spectra. Independent 15N-labelling of the nitrogen atoms of the amino and isothiocyanate groups yields assignments for the internal vibrations of both groups and enables the metal-amine and metal—isothiocyanate stretching vibrations (vM-NH2 and vM-NCS) to be distinguished. Both vM-NH2 and vM-NCS are metal ion dependent in the Irving-Williams sequence (Co Zn) expected from their proposed structures while the vN-H and vN-CS vibrations are inversely related to the masses of the coordinated metal ions.

The infrared spectra (500-150 CM−1) of the complexes cis- and trans-[Pt(pyridine)2X2] (X = Cl, Br, I, SCN)

Abstract The IR spectra of cis - and trans -[Pt(pyridine) 2 X 2 ] (X = Cl, Br, I, SCN) are discussed. Distinction between the v Pt—N and v Pt—X bands is based on their relative sensitivities to 15 N -labelling and deuteration of the pyridine ring, to halogen substitution and to 15 NCS-labelling. Two v Pt—N and two v Pt—X bands are observed in the cis -complexes as required for C 2v symmetry. The D 2h symmetry of the trans -complexes requires one v Pt-N and one v Pt—X band but additional bands are observed and are ascribed to coupling between v Pt—N and v Pt—X.

Haloalkyl complexes of the transition metals: IV. The formation of a cationic ylide complex of platinum(II) from a chloromethylplatinum(II) complex and the crystal structures of cis-[Pt(CH2PPh3)X(PPh3)2]I (X = Cl or I)

Abstract The reactions of Pt(PPH 3 ) 4 and Pt(C 2 H 4 )(PPh 3 ) 2 with CH 2 ClI have been investigated. The product of the reaction of Pt(PPh 3 ) 4 with CH 2 ClI is the cationic ylide complex cis -[Pt(CH 2 PPh 3 )Cl(PPh 3 )2][I], whereas the reaction of Pt(C 2 H 4 )-(PPh 3 ) 2 gives the oxidative addition product Pt(CH 2 Cl)I(PPh 3 ) 2 . Reaction of cis - or trans -Pt(CH 2 Cl)I(PPh 3 ) 2 ] with PPh 3 gives the complex cis -[Pt(CH 2 PPh 3 )-Cl(PPh 3 ) 2 ][I]. The structures of the complexes cis -[Pt(CH 2 PPh 3 X(PPh 3 ) 2 ][I] (where X = Cl or I) have been determined by X-ray crystallography. Both complexes crystalize in the monoclinic space group P 2 1 / n . For X = Cl a 1388.6(7), b 2026.7(10), c 1823.9(9) pm, β 96.51(2)° and R converged to 0.075 for 3542 observed reflections; structural parameters Pt-Cl 240(1), Pt-C(3) 212(2), Pt-P(2) ( trans to Cl) 235(1) and Pt-P(1) ( trans to CH 2 PPh 3 ) 233(1) pm; Cl-Pt-C(3) 86.9(5), C(3)-Pt-P(2) 91.8(5), P(2)-Pt-P(1) 97.0(2) and P(1)-Pt-Cl 85.1(2)°. For X = I, a 1379.4(7), b 2044.4(10), c 1840.0(9) pm, β 96.09(2)° and R converged to 0.071 for 4333 observed reflections; structural parameters Pt-I 266(1), Pt-C(3) 212(2), Pt-P(2) ( trans to I) 226(1) and Pt-P(1) ( trans to CH 2 PPh 3 233(1) pm; I-Pt-C(3) 87.2(5), C(3)-Pt-P(2) 91.5(5), P(2)-Pt-P(1) 96.5(2) and P(1)-Pt-I 85.6(1)°. Some other complexes of the type cis -[Pt(CH 2 PPh 3 )X(PPh 3 ) 2 ]Y are also described.

The far infrared spectra of pyridine adducts of nickel(II) acetylacetonate

Abstract The infrared spectrum (650–150 cm −1 ) of trans -[Ni(AA) 2 (py) 2 ] (where AA = acetylacetonate anion and py = pyridine) is discussed in relation to the band shifts induced by deuteration of the pyridine ring and substitution of the Ni II ion by Co II and Zn II . The results lead to a revision of some previously-proposed assignments based on isotopic labelling of the metal ion. The effects on the spectra which result from introducing a variety of substituents into the pyridine ring are discussed. After allowing for mass effects, electron-withdrawing pyridine substituents are found to decrease v (Ni-N). An opposite trend is exhibited by v (Ni-0).

Far infrared spectra (500–50 cm−1) of the 2,2′-bipyridine complexes of palladium and platinum halides

SummaryThe far-i.r. spectra of the title complexes have been examined. Band assignments are based on the shifts induced by ligand deuteration and halide substitution. Deuteration of bipyridine causes large shifts (Δν >10 cm−1) in internal ligand modes, intermediate shifts Δν between 2 and 9 cm−1) in metal-nitrogen stretching and bending modes and small to zero shifts in metal-halide stretching and bending vibrations. Generally, the requirements for square planarC2v synanetry [two ν(M−N) and two ν(M−X) bands] are observed. Previous ambiguities in the assignment of the ν(M−N) bands have been resolved by the isotopic labelling technique employed in this study.

Complexes of 8-Aminoouinoline. II. The Infrared Spectra of the Bisand Mono(Aminoquinoline) Complexes of Metal(II) Halides

Abstract The infrared spectra of the complexes M(aq)2(H2O)2X2 (M = Fe, Co, Ni, Cu; aq = 8-aminoquinoline; X =Cl, Br) have been determined over the range 4000-50 cm−1. Absence of vM-X bands indicates that the halide is not coordinated to the metal ion and the complexes are correctly formulated [M(aq)2-(H2O)2]X2. Deuteration of the amino group and the effects of metal ion substitution enable assignment of the vM-NH2, vM-N and vM-OH2 modes as well as the amino group vibrations. 18 O-Labelling assists in identifying the vO-H, vO-H……X and δO-H bands. The spectra are consistent with trans-octahedral coordination and axial bonding of the water molecules. The far infrared spectra of the mono(aminoquinoline) complexes [M(aq)X2]n (M = Cu, Zn; X = Cl, Br) are consistent with the proposed structure of polymeric octahedral coordination involving both bridging and terminal M-X bonds. The vM-NH2, vM-N, vM-X(terminal) and vM-X(bridging) bands are assigned by studying the effects of amino group deuteration, metal ion subs...

The far-infrared spectra of pyridine complexes of transition metal(II) isothiocyanates

Abstract The infrared spectra (500–140 cm −1 ) of the complexes [M(pyridine) n (NCS) 2 ] (n = 2, M = Mn, Co, Ni, Cu, or Zn; n = 4, M = Mn, Fe, Co, or Ni) are discussed. The v /M-pyridine and v /M-NCS bands are assigned by observing the band shifts induced by isotopic labelling of the coordinated pyridine and isothiocyanate, by comparing the spectra with those of the [M(pyridine) 2 Cl 2 ] complexes and from symmetry considerations based on their known structures. The two types of metal-ligand stretching bands occur within a rather narrow frequency range and there is evidence of some vibrational coupling between these two modes. Some earlier assignments of v M-pyridine bands require revision. The spectra of the yellow [Fe(py) 4 (NCS) 2 ] complex and its violet oxidation product suggest that the oxidation reaction involves the transformation of trans -[Fe(py) 4 (NCS) 2 ] into cis -[Fe(py) 3 (NCS) 3 ]

Complexes of 8-Aminoquinoline. I. The Infrared Spectra of the Ligand, the Tris Complexes of Iron, Cobalt and Nickel Perchlorates and Their ND2 Analogues

Abstract Deuteration of 8-aminoquinoline (aq) at the amino groups and comparison of the infrared spectrum of aq with those of aniline and quinoline enables reliable assignments to be proposed for the amino stretching and bending modes and the internal modes of the aminoquinoline rings. The spectra of the tris(8-aminoquinoline) complexes of iron, cobalt and nickel perchlorates have been examined over the range 4000–50 cm−1 with assignments based on the ligand study and the effects of metal ion substitution and deuteration of the nickel complex. The existence of two vM-NH2 and two vM-N(aq) bands is consistent with facial (cis-cis) octahedral coordination about the metal ion.