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Described are the synthesis and characterization of Ru(II) complexes of the type Ru[Cl.sub.2][L.sub.2](N-O), where [L.sub.2] is either 1,4-bis (diphenylphosphino)butane (dppb) or [(P[Ph.sub.3]).sub.2], and N-O represents chelated 2-benzoylpyridine (2-bzpy) or 2-acetylpyridine (2-acpy); the Ru presursors used were [Ru[Cl.sub.2][(dppb)].sub.2] ([mu]-dppb) or Ru[Cl.sub.2][(P[Ph.sub.3]).sub.3]. The crystal structure of cis-Ru[C1.sub.2](dppb)(2-bzpy) is presented, and three other Ru[Cl.sub.2][L.sub.2](N-O) complexes with cis-chlorines are isolated and characterized spectroscopically; of the trans-dichloro species, Ru[Cl.sub.2][(P[Ph.sub.3]).sub.2](N-O) complexes are isolated, while the corresponding dppb species are characterized in situ. In all cases, thermodynamically stable cis-complexes are formed from initially formed trans-species. Key words: ruthenium, phosphines, 2-benzoylpyridine, 2-acetylpyridine, X-ray structures.

The ruthenium(II) complex, [Ru[Cl.sub.2](NO)L] (I), (L = [[(2-py).sub.2]P[C.sub.2][H.sub.4]P[O.sub.2](2-py)]-) was obtained from recrystallization of Ru[Cl.sub.3]NO(d2pype) (d2pype = [(2-py).sub.2]P[C.sub.2][H.sub.4]P[(2-py).sub.2]) in the presence of HN[O.sub.3], crystallizing in the monoclinic space group [P2.sub.1] (no. 4), with a = 8.012(4) [Angstrom], b = 14.454(4) [Angstrom], c = 9.353(3) [Angstrom], [beta] = 105.77(3)[degrees], and Z = 2. Crystals of the DMSO solvate of the complex (II) were obtained from [(C[D.sub.3]).sub.2]SO solution, crystallizing in the monoclinic space group [P2.sub.1]/c (no.14) with a = 9.7080(2) [Angstrom], b = 22.2920(5) [Angstrom], c = 11.5230(3) [Angstrom], [beta] = 92.0450(10)[degrees], and Z = 4. In both complexes, the geometry about the ruthenium atom is a distorted octahedron mainly as a result of the tridentate [P,N,O]-bonding mode of L. The v (NO) bands at 1875 [cm.sup-1] in both complexes are consistent with the linear disposition of the NO group and the Ru atom as is observed in the X-ray crystal structure (Ru-N1-O1 angle = 178.5(4)[degrees]). Key words: pyridylphosphine, nitrosyl, ruthenium complex, X-ray structure.

An experiment has been developed for students of inorganic chemistry. In it they undertake synthesis of (RuCl(sub.2)(dppb)(PPH(sub.3))) and identification of the cis- and trans-(RuCl(sub.2)(dppb)(phen)) geometrical isomers using (super.31)P((super.1)H) NMR spectroscopy. All materials are commercially available and used as received. Students learn about setting up semirigorous inert atmosphere conditions and about spin-spin coupling for P atoms by assigning signals to equivalent and nonequivalent atoms.

A cyclic voltammetry (CV) experiment has been developed for students of inorganic chemistry. In this electrochemical experiment they monitor the isomerization of trans- to cis-(RuCl(sub.2)(dppb)(phen)). Students would have completed a lecture series on basic coordination chemistry and associated electrochemical techniques. They would have an understanding of linear sweep voltammetry at solid electrodes. CV theory need not have been extensively covered.

The ruthenium(II) complex, [RuCl[sub 2] (NO)L] (I), (L = [(2-py)[sub 2] PC[sub 2] H[sub 4] PO[sub 2] (2-py)][sup -] ) was obtained from recrystallization of RuCl[sub 3] NO(d2pype) (d2pype = (2-py)[sub 2] PC[sub 2] H[sub 4] P(2-py)[sub 2] ) in the presence of HNO[sub 3] , crystallizing in the monoclinic space group P2[sub 1 ] (no. 4), with a = 8.012(4) Å, b = 14.454(4) Å, c = 9.353(3) Å, β = 105.77(3)°, and Z = 2. Crystals of the DMSO solvate of the complex (II) were obtained from (CD[sub 3] )[sub 2] SO solution, crystallizing in the monoclinic space group P2[sub 1] /c (no.14) with a = 9.7080(2) Å, b = 22.2920(5) Å, c = 11.5230(3) Å, β = 92.0450(10)°, and Z = 4. In both complexes, the geometry about the ruthenium atom is a distorted octahedron mainly as a result of the tridentate [P,N,O]-bonding mode of L. The ν (NO) bands at 1875 cm[sup –1] in both complexes are consistent with the linear disposition of the NO group and the Ru atom as is observed in the X-ray crystal structure (Ru-N1-O1 angle = 178.5(4)°).Key words: pyridylphosphine, nitrosyl, ruthenium complex, X-ray structure.La recristallisation du RuCl[sub 3] NO(d2pype) (d2pype = (2-(py)[sub 2] PC[sub 2] H[sub 4] P(2-py)[sub 2] ) en présence de HNO[sub 3] conduit à la formation du complexe de ruthénium(II), [RuCl[sub 2] (NO)L] (1), (L = [(2-py)[sub 2] PC[sub 2] H[sub 4] P(2py)[sub 2] )][sup -] ) qui cristallise dans le groupe d'espace P2[sub 1] (no. 4), avec a = 8,012(4) Å, b = 14,454(4) Å et c = 9,353(3) Å, β = 105,77(3)° et Z = 2. Les cristaux du produit de solvatation du complexe par le DMSO (2) ont été obtenus à partir d'une solution de (CD[sub 3] )[sub 2] SO; ils cristallisent dans le groupe d'espace P2[sub 1] /c (no.14) avec a = 9,7080(2) Å, b = 22,2920(5) Å et c = 11,5230(3) Å, β = 92,0450(10)° et Z = 4. Dans les deux complexes, la géométrie autour de l'atome de ruthénium est un octaèdre déformé en raison principalement du mode de liaison tridentate [P,N,O] de L. Les fréquences des bandes NO, à 1875 cm[sup –1] , dans les deux complexes sont en accord avec une disposition linéaire du groupe NO et de l'atome de Ru; c'est ce qui est observé dans la structure cristalline obtenue par diffraction des rayons X alors que l'angle Ru-N1-O1 est de 178,5(4)°.Mots clés : pyridylphosphine, nitrosyle, complexe du ruthénium, structure cristalline par diffraction des rayons X.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Presents an undergraduate inorganic chemistry experiment that demonstrates the ability of [super 31]P{[super 1]H} nuclear magnetic resonance spectroscopy to distinguish between cis and trans geometric isomers of coordination compounds in solution. Description of concept of spin-spin coupling for phosphorus atoms.

Abstract: The “Ru(P–P)” unit (P–P=diphosphine) is recognized to be an important core in catalytic species for hydrogenation of unsaturated organic substrates. Thus, in this study we synthesized six new complexes containing this core, including the binuclear complex [(dppb)(CO)Cl2Ru-pz-RuCl2(CO)(dppb)] (pz=pyrazine) which can be used as a precursor for the synthesis of cationic carbonyl species of general formula [RuCl(CO)(dppb)(N–N)]PF6 (N–N=diimine). Complexes with the formula [RuCl(py)(dppb)(N–N)]PF6 were synthesized by exhaustive electrolysis of these carbonyl compounds or from the precursors [RuCl2(dppb)(N–N)]. The new complexes were characterized by microanalysis, conductivity measurements, IR and 31P{1H} NMR spectroscopy, cyclic voltammetry and X-ray crystallography. [Copyright &y& Elsevier]

A series of [RuCl2(dppb)(4,4′-X2-2,2′-bipy)] complexes was synthesized from [RuCl2(dppb)(PPh3)] and 4,4′-X2-2,2′-bipy [dppb=1,4-bis(diphenylphosphino)butane and 4,4′-X2-2,2′-bipy=2,2′-bipyridine (bipy), 4,4′-dimethoxy-2,2′-bipyridine (MeO-bipy), 4,4′-dimethyl-2,2′-bipyridine (Me-bipy), 4,4′-dicarboxy-2,2′-bipyridine (COOH-bipy), 4,4′-dithiomethyl-2,2′-bipyridine (MeS-bipy), 4,4′-dichloro-2,2′-bipyridine (Cl-bipy), 4,4′-dinitro-2,2′-bipyridine (NO2-bipy), and 4,4′-dithiomethylsulphoxide-2,2′-bipyridine (MeS&z.dbnd6;O-bipy)]. The complexes were characterized by elemental analysis, cyclic voltammetry and differential pulse voltammetry, and by UV–Vis and 31P{1H}NMR spectroscopies. The pKa of the ligands were determined. The trans-[RuCl2(dppb)(4,4′-X2-2,2′-bipy)] complexes were photoisomerized under white light and the isomerization rate constants from trans to cis isomers were consistent with first order reactions and were correlated with the pKa of the ligands and with the E1/2 of the complexes. The suggested mechanism of isomerization reactions is consistent with an intramolecular twist process. [Copyright &y& Elsevier]