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The composition and equilibrium constants of iron(III) complexes with two bidentate ligands: dopamine (H 3 L + ) and 8-hydroxyquinoline-5-sulphonic acid (H 2 L), have been studied in aqueous solution (NaClO 4 μ = 1) at 25°C, with protometric and spectrophotometric methods. With dopamine, seven complexes have been obtained in the pH range 0.5–12.0. In addition to the three stepwise complexes Fe(HL) n and the three deprotonated forms of Fe(HL) 3 , an acidic species Fe(H 2 L) 3+ occurs in a large pH range (0–5). 8-hydroxyquinoline-5-sulphonic acid proves to be a very good chelating agent; up to pH = 7, it is better than dopamine and most catecholate ligands.

Iron-chelating properties have been studied with N-ethyl-3,4-dihydroxybenzene-sulphonamide and 5-substituted dihydroxybenzamides as model molecules of β-lactam antibiotics to which are attached similar derivatized catechols. Acidity constants of the model ligands and equilibrium constants of iron(III) complexes have been determined by potentiometry and spectrophotometry at 25°C and 1 mol dm −3 ionic strength (NaClO 4 ). The formation constants show that these ligands form exceptionally stable complexes (log β 3 ⋍ 40) with the ferric ion, which is coordinated through the two phenolic oxygens of the catechol group. No precise correlation between stability constants of Fe 3+ complexes and in vitro microbiological properties has been made. However, it appears that the most potent antibiotics are those bearing substituted catechols possessing the highest chelating properties and lowest p K a 1 values.

A series of 17N-arylpyrrole-2-aldimine ligands has been synthesized by condensation of pyrrole-2-carboxaldehyde and substituted anilines. All CuL2 complexes are square, whereas NiL2 compounds are square, tetrahedral or eventually present a square α tetrahedral equilibrium. Attempts of chemical oxidation have shown the existence of nickel(III) and copper(III) in solution.

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The crystal and molecular structures of two dinuclear Co(II) compounds of formula [Co 2 I 4 (L) 2 ](C 6 H 6 ) n (L = PPh 3 or OPPh 3 ; n = 1,2) are described. Compound ( a ) with L = PPh 3 crystallizes in the triclinic space group P 1 with a = 12.769(4), b = 12.447(4) and c = 9.338(6) A, α = 113.82(4), β= 94.21(4), γ = 110.20(2)°; Z = 1. Compound ( b ) with L = OPPh 3 crystallizes in the monoclinic space group C 2/ c with a = 23.649(4), b = 9.984(3), c = 22.153(4) A, β = 109.92(2)°; Z = 4. The structures of both compounds are very similar and consist of centrosymmetric dinuclear Co 2 I 2 units, with CoI distances of 2.614 and 2.623 A in ( a ); 2.648 and 2.653 A in ( b ) and CoICo angles of 78.8° ( a ), 79.3° ( b ). The tetrahedral coordination around Co is completed by an iodide ion (distances of 2.52 A ( a ) and 2.53 A ( b )) and a ligand donor atom (CoP in ( a ) = 2.36 A and CoO in ( b ) = 1.917 A). The dimeric Co 2 I 2 has a planar geometry which appears to be solely determined by the size of iodide ions, with Co⋯Co distances of 3.32 A in ( a ) and 3.38 A in ( b ) and I⋯I bridge distances 4.05 A ( a ) and 4.08 A ( b ). These II contacts are about equal to twice the van der Waals radius of iodide ions. The benzenes are present as lattice molecules. Ligand-field and far-IR spectra are consistent with the tetrahedral geometry for cobalt(II). The magnetic exchange between the cobalt(II) ions appears to be strongly antiferromagnetic, as deduced from magnetic susceptibility studies at temperatures down to 4 K. Fitting with a Heisenberg S = 1 2 dimer results in J values of −33 K ( a ) and −35 K ( b ), with g values of 2.45 ( a ) and 2.95 ( b ).

Des mesures de RPE sur des echantillons polycristallins de composes octaedriques du cobalt (II) : CoL6 Y2 et a structure mixte, octaedrique-tetraedrique, |CoL6 ||CoX4 ou L = uree, N,N'-dimethyluree et N.N'-diethyluree, X = Cl, Br, I ou NCS et Y = ClO4 et I, ont ete effectuees a 4,2 K. Les facteurs g, les formes et largeurs de raies ainsi que quelques constantes de structure hyperfine ont ete determinees. Les composes octaedriques CoL6 Y2 ont une structure electronique distordue et presentent des interactions dipolaires. Dans les composes a structure mixte, les interactions sont plus complexes a la fois dipolaires et d’echange.

Les spectres Raman des complexes se formant en solution aqueuse entre les ions cyanure et le cuivre (I) ont ete determines et les frequences vCN obtenues sont (en cm-1 ) : [math] (2 078, 2 094), [math] (2 094, 2 108) et [math] (2 137). Ceci est en accord avec les structures respectives : tetraedrique (Td), trigonale plane (D3h et lineaire (D∞h ). A partir des donnees basses frequences (nouvelles pour [math]), une analyse en coordonnees normales a ete effectuee, permettant de calculer un modele de constantes de force pour les especes [math] et [math]; les distributions d’energie potentielle, cinetique et totale presentent une grande analogie pour des vibrations de meme type. Un modele approche pour l’ion [math] montre la coherence avec les autres resultats. Les constantes de force principales obtenues (fCu-C — fC-N en mdyne/A) sont respectivement pour [math] (1,1-16,4), [math] (1,3 — 16,7), Cu(CN)2 – (1,7—17,2). La nature de la liaison carbone-cuivre est discutee et une comparaison avec des especes isoelectroniques est tentee.

The reactions of CoBr 2 (PPh 3 ) 2 at 25°C in benzene with Ph 2 P(CH 2 ) n PPh 2 with n = 1 (dpm), n = 2 (dpe) and n = 3 (dpp) have been followed spectrophotometrically and by conductivity measurements in CH 2 Cl 2 . The addition and substitution steps of the bidentate bisphosphines LL on the initial cobalt complex have been identified and the equilibrium constants calculated at different wavelengths using least squares methods. With dpm, binuclear species are formed in three steps with bridging dpm molecules. With dpe and dpp, two steps are observed with the formation of the final red penta-coordinated complexes [CoBr(LL) 2 ]Br; the intermediate complexes are different in each case. The overall constant for the equilibrium CoBr 2 (PPh 3 ) 2 +2LLα[CoBr(LL) 2 ]Br+2PPh 3 is 1.06 x 10 5 for dpe and 1.20 x 10 3 for dpp, and depends on the size of the chelate rings.

The complexes M bi 2 X 2 with M = Mn, Co, Ni and Cu, X = Cl, Br and I have been prepared. IR spectra and magnetic properties are given. The analysis of the ligand field parameters obtained from the electronic spectra for the cobalt and nickel compounds are in agreement with a trans octahedral structure.

Octahedral and mixed octahedral-tetrahedral complexes of nickel(II) and cobalt(II) with N,N′-dimethylurea (L) have been prepared: ML6Y2 with M = Ni, Y = Br, I, ClO4 and with M = Co, Y = I, ClO4; NiL4(NCS)2; [ML6][MX4] with M = Ni, X = Cl, Br and with M = Co, X = Cl, Br, I, NCS. The structures with the ligand coordinated through the oxygen atom are supported by infrared and electronic spectra and magnetic data. The blue complex [NiL6][NiCl4] is isomerized in solid state into a red pentacoordinated high-spin complex NiL3Cl2.

Resume Les complexes suivants du manganese(II) avec la N,N′-diethyluree ont ete prepares: Mn (DEU) 3 X 2 avec X = Cl − , Br − et Mn(DEU) 6 Y 2 avec Y = Br − , I − , ClO 4 − . Ils on ete etudies a l'aide de leurs spectres i.r. (4000-200 cm −1 ), leurs spectres electroniques et leurs proprietes magnetiques. La coordination de la N,N′-diethyluree se fait par l'atome d'oxygene. Les composes |Mn(DEU) 6 | Y 2 sont octaedriques tandis que les autres composes sont a formuler: |Mn(DEU) 6 |Mn X 4 |, avec une coordination du manganese octaedrique et tetraedrique.

Resume L'action de la pyridine sur les β-dicetonates de nickel(II) dans le chlorure de methylene, a eteetudiee par spectrophotometrie dans le visible. Les equilibres suivants avec formation d'une espece dinucleaire Ni2L4py ont ete mis en evidence: Ni3L6 ⇄ 3NiL2K 2Ni3L6 + 3py ⇄ 3Ni2L4py K1 Ni2L4py + 3py ⇄ 2NiL2py2K2. L est l'anion acetylacetonate (AA), l'anion benzoylacetonate (BA), et l'anion du dibenzoylmethane (DBM). L'ordre de stabilite vis a vis de la pyridine est le suivant: Ni3(BA)6 ⪡ Ni3(AA)6 Les constantes d'equilibres sont pour: L = AA, K = 4,10−6mole2.1−2, K1 = 4,3.1011mole−2.12. et K2 = 4.106mole−2. l2. Pour L = BA, K = 2.10−5mole2.1−2., K1 = 3.1014mole−2.12. et K2 = 1,8.107mole−2. 12. Pour L + DBM: K = 2,3.10−6mole2.1−2., K1 = 9.1012mole−2.12. et K2 = 1.106mole−21.2.

Resume Les complexes formes entre le nickel(II) et les acides (methylenedithio) diacetique (H 2 M): CH 2 (S CH 2 COOH) 2 , (ethylenedithio) diacetique (H 2 E): (CH 2 ) 2 (S CH 2 COOH) 2 et (trimethylenedithio) diacetique (H 2 T): CH 2 ) 3 (S CH 2 COOH) 2 ont ete etudies, a 25°C en milieu NaClO 4 2M, par potentiometrie et spectrophotometrie. Les constantes de stabilite sont respectivement pour l'acide H 2 M log β NiHM = 0,85 ± 0,07 et log β 1 = 1,31 ± 0,05, pour l'acide H 2 E log β NiHE = 2,95 ± 0,05 et log β 1 = 4,58 ± 0,05, pour l'acide H 2 T log β NiHT = 1,55 ± 0,10 et log β 1 = 2,70 ± 0,05. Deux composes solides de formules Ni E (OH 2 ) 2 et Ni T (OH 2 ) 2 ont ete prepares et etudies.

Resume Les constantes de depolymerisation, dans le chlorure de methylene, a 25°C, des trimeres des complexes suivants ont ete determinees par spectrophotometrie: le bis(acetylacetonato)Ni(II) [Ni3(AA)6], le bis(benzoylacetonato)Ni(II) [Ni3(BA)6] et le bis(dibenzoylmethanato)Ni(II) [Ni3-(DBM)6]. Les constantes K = ( Monom e re ) 3 /( Trim e re ) sont respectivement egales a (4±2,5) × 10−6−(2±1) × 10−5 et (2,3±0,3) × 10−6 moles2/l−2. Une discussion faisant intervenir des facteurs structuraux et electroniques pour expliquer l'ordre de stabilite trouve est presentee. Pour les complexes du nickel(II) avec la trifluoroacetylacetone, la benzoyl-trifluoroacetone et l'hexafluoroacetylacetone une stabilite particulierement grande de la forme polymere a coordinence 6 est observee.

The reactions of CoBr 2 (PPh 3 ) 2 at 25°C in benzene with Ph 2 P(CH 2 ) n PPh 2 with n = 1 (dpm), n = 2 (dpe) and n = 3 (dpp) have been followed spectrophotometrically and by conductivity measurements in CH 2 Cl 2 . The addition and substitution steps of the bidentate bisphosphines LL on the initial cobalt complex have been identified and the equilibrium constants calculated at different wavelengths using least squares methods. With dpm, binuclear species are formed in three steps with bridging dpm molecules. With dpe and dpp, two steps are observed with the formation of the final red penta-coordinated complexes [CoBr(LL) 2 ]Br; the intermediate complexes are different in each case. The overall constant for the equilibrium CoBr 2 (PPh 3 ) 2 +2LLα[CoBr(LL) 2 ]Br+2PPh 3 is 1.06 x 10 5 for dpe and 1.20 x 10 3 for dpp, and depends on the size of the chelate rings.

Die 1:1-molare Reaktion der Liganden in DMSO mit den Metallperchloraten in Gegenwart von NaOH liefert die Komplexe (I), in denen die Liganden uber ihre deprotonierten Amidgruppen koordiniert sind.

Die durch 1:2-molare Umsetzung von C012 und dem Phosphin bzw. Phosphinoxid in siedendem Benzol dargestellten Titelkomplexe (I) werden durch Rontgenstrukturanalyse, Ligandenfeld- u. IR-Spektren SOWiC magnetische Suszeptibilitatsmessungen, aus denen auf einen starken antiferromagnetischen Austausch zwischen den Co(II)-Ionen geschlossen wird, charakterisiert.

Die Bildungskonstanten der Komplexe (I)-(III) wurden potentiometrisch und spektrophotometrisch bestimmt.

X-Ray structure analysis shows that the high-spin complex dibromotris(NN′-dimethylurea-O)manganese(II) has a trigonal bipyramidal geometry with the bromine atoms in equatorial positions and with two types of bonding for the neutral ligands, one of them being very unusual.

IT is now well established that the bis-(β-ketoenolato)-metal(II) compounds of manganese, iron, cobalt, nickel and zinc polymerize to form trimers or tetramers1–5, unless they are prevented from so doing by steric hindrance6–8. Although the structures of these polymers vary considerably, their common feature, and the putative cause of their formation, is the tendency of the metal atom to have a co-ordination number greater than four. This is accomplished by the sharing of some oxygen atoms (bridging atoms in the polymeric structures) between metal atoms.