C. Owens

2,2′-bipyridine- and 1,10-phenanthroline-N-oxide chelates with chromium(III) and iron(III) nitrates[1]

Abstract The syntheses and characterization of Cr(III) and Fe(III) nitrate chelates with 2,2′-bipyridine- and 1,10-phenanthroline-N-oxides(N-bipyO and N-phenO, respectively) are reported. Cr(NO3)3 yields chelates of the types [Cr(N-bipyO)(O2NO)2] (NO3) and [Cr(N-phenO)2(O2NO)] (NO3)2·2C2H5OH, involving both N-oxide and nitrato ligands in the complex cations. Lattice ethanol is also present in the latter complex. In the case of Fe(NO3)3, both 1:3 and 1:2 complexes with these ligands were obtained. The 1:3 complexes are of the type [FeL3](NO3)3(L = N-bipyO, N-phenO) and are characterized by subnormal, for a high-spin configuration, room temperature magnetic moments, which were attributed to spin-free-spin-paired equilibria, on the basis of studies of magnetic susceptibility variations with temperature. The 1:2 complexes are of the types [Fe(N-bipyO)2(ONO2)2] (NO3) and [Fe(N-phenO)2(O2NO)] (NO3)2, the former involving unidentate and the latter bidentate coordinated nitrate. These chelates, as well as the new Cr(III) chelates, are magnetically normal, high-spin compounds.

2,2′-bipyridine n-oxide and 1,10-phenanthroline n-oxide complexes with divalent 3d metal nitrates☆

Abstract The synthesis of divalent 3d metal nitrate complexes with 2,2′-bipyridine N-oxide (N-bipyO) and 1,10-phenanthroline N-oxide (N-phenO) is reported. The new complexes were characterized by means of their i.r. and electronic spectra, magnetic moments, and molar conductivities in solution. In the case of N-bipyO, mixed ligand complexes, i.e. containing both ligand and nitrate coordinated to the central metal ion, are formed. For N-phenO both tris and mixed ligand complexes are formed and in some cases may be obtained from the same metal ion. The nitrate anion exhibits bidentate, monodentate, and ionic modes of bonding in the mixed ligand complexes. The mono N-oxides function as bidentate, O,N-chelating agents. The u.v.-spectra of the new metal complexes are characterized by the presence of ligand, electron-transfer (metal-to-ligand) and (d-d) bands.

Quinoxaline 1,4-dioxide complexes with 3d metal perchlorates[1]

Abstract A series of 3 d metal perchlorate complexes with quinoxaline 1,4-dioxide(L) were synthesized and characterized by means of IR and electronic spectral and magnetic susceptibility (at 297-143 or 80°K) studies. With the exception of a 4:1 LCu(ClO 4 ) 2 complex, which is apparently monomeric, pentacoordinated of the type [CuL 4 (OClO 3 )](ClO 4 ), the spectral and magnetic evidence is in favor of bi- or polynuclear structures, involving terminal (L t ) and bridging quinoxaline 1,4-dioxide, aqua and unidentate perchlorato ligands, as well as ionic ClO 4 − and lattice water. The magnetic data point to significant spin-spin interactions in these bi- or polynuclear complexes; this is suggestive of coordination of the bridging L groups through only one of their NO oxygens, which acts as a bridge between neighboring metal ions (M M or M(L b ) 2 M bridging) rather than functioning as bidentate, with each of the NO oxygens coordinating to a different metal ion (M( b L b )M bridges). Proposed structural types are as follows for the binuclear, hexacoordinated new complexes: [(H 2 O)(O 3 ClO) 2 (L t )Cr(L b ) 2 Cr(L t )(OClO 3 ) 2 (OH 2 )](ClO 4 ) 2 ·6H 2 O; (H 2 O)(O 3 ClO)(L t ) 2 Fe(L b ) 2 Fe(L t ) 2 (OClO 3 )(OH 2 )](ClO 4 ) 4 ·8H 2 O; and [(H 2 O)(O 3 ClO)(L t ) 2 M(L b ) 2 M(L t ) 2 (OClO 3 )(OH 2 )](ClO 4 ) 2 · 10H 2 O (M = Mn, Fe, Co, Ni, Zn). For a second Cu(II) complex, involving a 3:2 L to Cu ratio, the relatively small μ eff decrease (0.29 μB) in the 295-82°K range, favors an oligomeric pentacoordinated structure, comprising both possible kinds of bridging L (i.e. characterized by −Cu(L b ) 2 Cu( b L b )- sequences).

Cobalt(II), nickel(II) and copper(II) nitrate complexes with pyrazine N-oxide

Abstract Interaction of pyrazine N-oxide(pyzNO) with 3 d metal nitrate salts yields a 2:1 complex with Co(II) and 4:1 complexes with Ni(II) and Cu(II). In the cases of Cr(III), Fe(III) and Zn(II) no solid complexes were obtained. The 4:1 complexes are monomeric and hexacoordinated, involving two monodentate nitrato ligands. Elucidation of the Co(II) complex is more difficult. The data suggests either a monomeric hexacoordinated compound with bidentate nitrato ligands or a polymeric compound with monodentate nitrato groups and both terminal and bridging pyzNO ligands. Solubility characteristics favor the former structure. Finally, comparison of the mull and KBr pellet i.r. spectra of the new complexes indicates that these compounds undergo rearrangements when pressed in a KBr die.

Studies of adduct formation between diisopropyl methylphosphonate and various metal salts and complexes

Abstract The formation of adducts of diisopropyl methylphosphonate (L) with a variety of metal salts and complexes was studied by means of conductimetric titrations and gas-solid interactions. Conductimetric titration data indicate that L forms 1:1 and 2:1 adducts with SnCl 4 , TiCl 4 , FeCl 3 and MnCl 2 ; in addition, the possibility of existence of 1.5:1, 3:1 and 6:1 adducts with FeCl 3 and a 4:1 adduct with MnCl 2 was suggested by the titration curves. Studies of the interaction of L vapor with solid metal salts and complexes, under a vacuum of 5 × 10 −5 mm Hg, suggest that adducts involving the following L to metal molar ratios are the most stable and, therefore, easiest to isolate species: 2:1 with MCl 2 (MCo, Ni, Cu, Zn) and NiX 2 (XBr, I, NO 3 ); 4:1 with Ni(ClO 4 ) 2 ; and 1:1 with Ni(II) acetylacetonate and nickelocene. Most of these adducts involve normal donor-acceptor interactions between L and metal ion, as shown by sizeable v P = O shifts to lower wavenumbers; however, the nickelocene adduct seems to involve a weak interaction of L and Ni 2+ ( Δv P = O of only 3 cm −1 ). NiF 2 and Ni(CH 3 COO) 2 did not uptake any L during gas-solid interaction, while IrCl 3 uptook only 0.15 mol L/mol, forming an authentic adduct on its surface. Finally, a number of new solid 2:1 adducts of L with metal salts were synthesized and characterized as follows: [MnX 2 L 2 ] (XCl, I), tetrahedral; [VCl 3 L 2 ] and [VOCl 2 L 2 ], both trigonal bipyramidal; [M(O 2 NO) 2 L 2 ] (MMn, Cd) and [Sn(O 2 SO 2 ) 2 L 2 ], low-symmetry hexacoordinated; [FeCl 2 L 4 ][FeCl 4 ], ionic with a hexacoordinated complex cation combined with the tetrahedral [FeCl 4 ] − .

Phenyl isocyanate interactions with tin(IV) halides

Abstract Studies of the interactions of phenyl isocyanate with SnX4 (X = Cl, Br, I) in carbon tetrachloride solution, at ambient temperature, and of the solid products isolated are reported. SnCl4 and SnBr4 yielded 1:2 adducts with C6H5NCO, under these experimental conditions. These complexes were characterized as octahedral trans-[SnX4(OCNC6H5)2]; the two phenyl isocyanate ligands are oxygen-bonded to the Sn4+ ion and occupy trans positions, relative to each other, in the first coordination sphere of this metal ion. Stabilization of the cis-isomers in the solid state is apparently sterically hindered, owing to the presence of the bulky phenyl substituent in the C6H5NCO ligand. The interaction of SnI4 with phenyl isocyanate resulted in the formation of reaction rather than addition products. A solid precipitate, formed in low yield, appears to be a mixture of organic compounds and a tin complex. The N:O (2:1) and Sn:I (1:1) atomic ratios in this precipitate, in combination with the infrared evidence, suggest that the reaction proceeds via either insertion of C6H5NCO between SnI bonds or partial ionization of SnI4 in the presence of the organic ligand, while the organic components of the solid product are mixtures or reaction products of C6H5NCO and phenylimido(C6H5N) group derivatives.

3d Metal perchlorate complexes with quinoxaline 1-oxide[1]

Abstract Hexacoordinated 3d metal perchlorate complexes with quinoxaline 1-oxide(N-QxO) were prepared and characterized by means of spectral and magnetic studies. Several of the new complexes involve exclusively oxygen-bonded unidentate N-QxO ligands and are probably of the types: [Cr(N-QxO)4(OH2)(OClO3)](ClO4)2·5H2O; [Fe(N-QxO)3(OH2)(OClO3)2](ClO4); and [M(N-QxO)4(OH2)2](ClO4)2·xH2O (MFe, Co, c Ni; x = 1 for Co; x = 6 for Fe or Ni). The rest of the new complexes contain some N- and some O-bonded N-QxO groups; likely formulations for these compounds are: [ Mn(ONC 8 H 6 N) n (NC 8 H 6 NO) 5−n (OClO 3 )](ClO 4 )·4H 2 O ; [ Zn(ONC 8 H 6 N) m (NC 8 H 6 NO) 3−n (OH 2 ) 3 ](ClO 4 ) 2 ; [ Cu(ONC 8 H 6 N)(NC 8 H 6 NO)(OH 2 ) 2 (O 2 ClO 2 )](ClO 4 )·H 2 O; and [ NC 8 H 6 NO) y (ONC 8 H 6 N) 3−y (O 3 ClO)Cu(NQxO) 2 Cu(OClO 3 )(NC 8 H 6 N) 3−y (ONC 8 6 N) y ](ClO 4 ) 2 ·4H 2 O . The latter complex is apparently the only binuclear compound of the series, involving two O-bonded bridging N-QxO ligands, as suggested by its subnormal magnetic moment (0.99 μB). The Fe(III) compound also shows a subnormal μeff (2.61 μB), which was attributed to spin-state equilibria, while the rest of the new complexes with paramagnetic metal ions are magnetically normal high-spin compounds.

Phenazine 5,10-dioxide complexes with 3d metal perchlorates☆

Abstract The syntheses and characterization of two series (i.e. prepared 1) in the absence of any dehydrating agent and 2) by treating ligand and salt solutions with moleucular sieve 4A prior to their interaction) of 3d metal perchlorate complexes with phenazine 5,10-dioxide (L) are reported. With metal(II) perchlorates, use of molecular sieve predrying leads to the precipitation of complexes involving higher L to metal ratios and a lower degree of hydration, relative to the compounds obtained in the absence of dehydrating agents. In contrast, with metal(III) perchlorates, when predrying with molecular sieve was employed, lower L to metal ratios (and in one occasion (Fe 3+ ) a higher degree of hydration) were observed. Most likely formulations for the new metal complexes, based on spectral and magnetic studies, are: Monomeric complexes: Hexacoordinated: [CrL 2 L 2 (OH 2 ) n (OClO 3 ) m ](ClO 4 ) 3− m ·(12- n )H 2 O ( m = 1 or 2; n = 3 or 2); [ML 2 (OH 2 ) 4 ](ClO 4 ) 2 ·2H 2 O (M = Mn, Co, Ni, Zn); [ML 3 (OH 2 ) 2 (OClO 3 )](ClO 4 ) (M = Mn, Fe); [FeL 3 (OH 2 ) 2 (OClO 3 ](ClO 4 ) 2 ; [ML 3 (OH 2 ) 2 (OClO 3 )](ClO 4 )·4H 2 O (M = Co,Ni); [ZnL 3 (OH 2 ) 2 (OClO 3 )](ClO 4 )·3H 2 O. Square-planar: [CuL 3 (OClO 3 )](ClO 4 )·H 2 O. Binuclear, hexacoordinated: [(O 3 ClO) x (H 2 O) y MLM(OH 2 ) y ∗ (OClO 3 ) x ](ClO 4 ) 6−2 x ·zH 2 O (M = Cr, Fe; x =2 or 1; y = 3 or 4; z = 18 or 16); [(H 2 O 4 LFeLFeL(OH 2 ) 4 ](ClO 4 ) 4 ·16H 2 O. The presence of two bulky and sterically hindered L ligands at cis -positions (relative to one another) in the inner coordination sphere of the central metal ion would result in severe steric interference and is, therefore, not favored. Consequently, among the preceding complexes, those containing two L groups per metal ion involve trans -[MX 4 L 2 ] n+ (X = H 2 O or OClO 3 ) complex cations. However, in the case of [MX 3 L 3 ] n+ or [CuXL 3 ] 2+ cationic complexes, at leastt one L ligand is, of necessity, at a cis -position relative to each of the other two L groups; the steric interactions imposed by such an arrangement of the ligands result in the presence of chemically non-equivalent sets of L ligands in the 3:1 complexes, as suggested by the IR evidence. The two new ferric complexes are magnetically subnormal, apparently involving spin-state equilibria, whilst the rest of the new metal complexes show normal magnetic properties for high-spin d 3 or d 5 − d 8 compounds or the d 9 configuration.

Ethoxy 6-methylpyridine-2-phosphonato complexes with 3d metal ions☆

Abstract Reaction of M Cl 2 ( M  Mn, Fe, Co, Ni, Cu, Zn) and M Cl 3 ( M  Ti, V, Cr, Fe) with diethyl 6-methylpyridine-2-phosphonate at elevated temperatures results in the precipitation of ethoxy 6-methylpyridine-2-phosphonate (E6MPP) metal complexes. Spectral evidence suggests that, in these compounds, E6MPP acts as a bidentate N,0-chelating agent. The new complexes were characterized by means of spectral and magnetic studies; the following structures are proposed: [ M (E6 M PP) 2 ] 2 ( M  Mn, Fe, Co, Ni): pentacoordinated, binuclear chelates containing two bridging and two terminal E6MPP ligands; one -POO oxygen acts as the bridging group in these complexes ( M  O  M bridges); M (E6MPP) 2 ( M  Cu, Zn): monomeric chelates, involving tetrahedral M O 2 N 2 moieties; M (E6MPP) 3 monomeric, distorted octahedral chelates, and Fe(E6MPP) 2 Cl, involving either a monomeric, pentacoordinated or a binuclear, chlorine bridged, hexacoordinated structure. The mechanism of formation of the new complexes is discussed, and preliminary data on the products of the reaction between 3 d metal dichlorides and diethyl pyridine- and 4-methylpyridine-2-phosphonates are presented.

X-ray crystallographic, morphological and thermal decomposition studies of 2:1 adducts of diisopropyl methylphosphonate with stannous and stannic halides

Abstract X-ray and morphological studies of monomeric, trans -square planar Sn(dimp) 2 X 2 ( X  Cl, Br; dimp = diisopropyl methylphosphonate) and trans -octahedral Sn(dimp) 2 X 4 ( X = Cl, Br, I) adducts revealed that the crystals of these compounds are triclinic, space group P 1. The Sn(II) and Sn(IV) chloride and bromide adducts have four molecules per unit cell, while the SnI 4 adduct has two molecules per unit cell. The two stannous halide adducts are almost isostructural. The X-ray powder patterns of the SnCl 4 and SnBr 4 complexes exhibit some similarities, but that of the SnI 4 adduct is significantly different. Studies of the thermal behavior of the Sn(IV) adducts at 140–210°C, indicated that Sn(dimp) 2 X 4 decomposes in two steps, i.e. (i) Formation of a linear oligomeric species of the type {[( i -C 3 H 7 O)CH 3 POO] 2 Sn X 2 } n ( n = 4 for X  Cl), involvin Sn(OPO) 2 Sn bridges, with simultaneous elimination of propylene and HX. (ii) Decomposition of the preceding oligomeric intermediate to yield highly cross-linked polymeric [(CH 3 PO 3 ) 2 Sn] n and isopropyl halide. Poor reproducibility in the amounts of volatile materials evolved from experiment to experiment did not allow the collection of consistent kinetic data for the thermal decomposition of Sn(dimp) 2 X 4 . The Sn(dimp) 2 X 2 adducts also decompose at elevated temperatures, yielding a linear, high polymer of the [(CH 3 (OH)POO) 2 Sn] n type, via formation of the {[( i -C 3 H 7 O)CH 3 POO] 2 Sn} n intermediate, which is subsequently attacked by the hydrogen halide present in the system.