Tris(2,2'-azobispyridine) complexes of copper(II): X-ray structures, reactivities, and the radical nonradical bis(ligand) analogues.

Tris(abpy) complexes of types mer-[Cu(II)(abpy)3][PF6]2 (mer-1(2+)[PF6(–)]2) and ctc-[Cu(II)(abpy)2(bpy)][PF6]2 (ctc-2(2+)[PF6(–)]2) were successfully isolated and characterized by spectra and single-crystal X-ray structure determinations (abpy = 2,2′-azobispyridine; bpy = 2,2′-bipyridine). Reactions of mer-1(2+) and ctc-2(2+) ions with catechol, o-aminophenol, p-phenylenediamine, and diphenylamine (Ph–NH–Ph) in 2:1 molar ratio afford [CuI(abpy)2](+) (3(+)) and corresponding quinone derivatives. The similar reactions of [Cu(II)(bpy)3](2+) and [Cu(II)(phen)3](2+) with these substrates yielding [Cu(I)(bpy)2](+) and [Cu(I)(phen)2](+) imply that these complexes undergo reduction-induced ligand dissociation reactions (phen = 1,10-phenanthroline).

Orthometalation of dibenzo[1,2]quinoxaline with ruthenium(II/III), osmium(II/III/IV), and rhodium(III) ions and orthometalated [RuNO](6/7) derivatives.

A new family of organometallics of ruthenium(II/III), osmium(II/III/IV), and rhodium(III) ions isolated from C-H activation reactions of dibenzo[1,2]quinoxaline (DBQ) using triphenylphosphine, carbonyl, and halides as coligands is reported. The CN-chelate complexes isolated are trans-[Ru(III)(DBQ)(PPh3)2Cl2] (1), trans-[Ru(II)(DBQ)(CO)(PPh3)2Cl] (2), trans-[Os(III)(DBQ)(PPh3)2Br2] (3), trans-[Os(II)(DBQ)(PPh3)2(CO)Br] (4), and trans-[Rh(III)(DBQ)(PPh3)2Cl2] (5). Reaction of 1 with NO affords trans-[Ru(DBQ)(NO)(PPh3)2Cl]Cl (6(+)Cl(-)), isoelectronic to 2, with a byproduct, [Ru(NO)(PPh3)2Cl3] (7).

Metal ion promoted tautomerization and C-N bond cleavage: conversion of catechol to a p-benzoquinone derivative.

Metal ion promoted tautomerization of p-iminoquinone to o-diiminoquinone and a C-N bond cleavage of 2,5-bis(p-tolylamino)-4-p-tolyliminobenzoquinone leading to the conversion of catechol to a p-benzoquinone derivative are reported.

Ruthenium, osmium and rhodium complexes of 1,4-diaryl 1,4-diazabutadiene: radical versus non-radical states.

Ruthenium, osmium and rhodium complexes of 1,4-di(3-nitrophenyl)-1,4-diazabutadiene (LDAB) of types trans-[RuII(LDAB)(PPh3)2Cl2] (1), trans-[OsII(LDAB)(PPh3)2Br2] (2) and trans-[Rh(LDAB)(PPh3)2Cl2] (3) are isolated and characterized by elemental analyses, IR, mass and 1H NMR spectra including the single crystal X-ray structure determination of 1·2toluene. The α-diimine fragment of the LDAB ligand in 1·2toluene is deformed, showing a relatively longer -C=N- bond, 1.320 Å, and a shorter =CH–CH= bond, 1.

Ruthenium, rhodium, osmium, and iridium complexes of osazones (osazones = bis-arylhydrazones of glyoxal): radical versus nonradical states.

Phenyl osazone (L(NHPh)H2), phenyl osazone anion radical (L(NHPh)H2(•-)), benzoyl osazone (L(NHCOPh)H2), benzoyl osazone anion radical (L(NHCOPh)H2(•-)), benzoyl osazone monoanion (L(NCOPh)HMe(-)), and anilido osazone (L(NHCONHPh)HMe) complexes of ruthenium, osmium, rhodium, and iridium of the types trans-[Os(L(NHPh)H2)(PPh3)2Br2] (3), trans-[Ir(L(NHPh)H2(•-))(PPh3)2Cl2] (4), trans-[Ru(L(NHCOPh)H2)(PPh3)2Cl2] (5), trans-[Os(L(NHCOPh)H2)(PPh3)2Br2] (6), trans- [Rh(L(NHCOPh)H2(•-))(PPh3)2Cl2] (7), trans-[Rh(L(NHCOPh)HMe(-))(PPh3)2Cl]PF6 ([8]PF6), and trans-[Ru(L(NHCONHPh)HMe)(PPh3)2Cl]Cl ([9]Cl) have been isolated and compared (osazones = bis-arylhydrazones of glyoxal). The complexes have been characterized by elemental analyses and IR, mass, and (1)H NMR spectra; in addition, single-crystal X-ray structure determinations of 5, 6, [8]PF6, and [9]Cl have been carried out. EPR spectra of 4 and 7 reveal that in the solid state they are osazone anion radical complexes (4, gav = 1.

Zinc(II), iron(II/III) and ruthenium(II) complexes of o-phenylenediamine derivatives: oxidative dehydrogenation and photoluminescence.

Reactions of benzoyl pyridine, o-phenylenediamine and anhydrous ZnX2 in methanol afford imine complexes [Zn(L1)X2] (X = Cl, 1; X = Br, 2) in good yields (L1 = (E)-N(1)-(phenyl(pyridin-2-yl)methylene)benzene-1,2-diamine). The reduction of 1 with NaBH4 affords (E)-N(1)-(phenyl(pyridine-2-yl)methylene)benzene-1,2-diamine (L2H). The reaction of L2H with [Ru(II)(PPh3)3Cl2] results in the oxidative dehydrogenation to L1 generating cis-[Ru(II)(L1)(PPh3)Cl2] (3).

Mono- and di-nuclear photoluminescent complexes of zinc(II), cadmium(II) and mercury(II) of a chiral diimine ligand.

Reaction of α-pyridoin and N-phenyl-o-phenylenediamine affords 2-(2-(phenylamino)phenylimino)-1,2-di(pyridin-2-yl)ethanol (L) which undergoes cyclization to a chiral diimine, 2-methoxy-1-phenyl-2,3-di(pyridin-2-yl)-1,2-dihydroquinoxaline, L(OMe) (conjugated 14πe system) in the presence of zinc(II), cadmium(II) and mercury(II) ions affording [Zn(L(OMe))Cl2] (1), [Cd2(L(OMe))2Cl4] (2) and [Hg2(L(OMe))2Cl4] (3) complexes. Ligand L and complexes 1-3 are substantiated by elemental analyses, mass, IR, (1)H NMR and UV-vis spectra including the single-crystal X-ray structures of 1 and 3. The possibility of the atropisomerism of L is restricted in cyclic L(OMe).

Oxidovanadium catechol complexes: radical versus non-radical states and redox series.

A new family of oxidovanadium complexes, [(L1(R))(VO)(L(R(')))] (R = H, R' = H, 1; R = H, R' = -CMe3, 2; R = H, R' = Me, 3; R = -CMe3, R' = H, 4 and R = -CMe3, R' = -CMe3, 5), incorporating tridentate L1(R)H ligands (L1(R)H = 2,4-di-R-6-{(2-(pyridin-2-yl)hydrazono)methyl}phenol) and substituted catechols (L(R('))H2) was substantiated. The V-Ophenolato (cis to V═O), V-OCAT (cis to V═O) and V-OCAT (trans to V═O) lengths span the ranges, 1.894(2)-1.

Asymmetric cleavage of 2,2'-pyridil to a picolinic acid anion radical coordinated to ruthenium(II): splitting of water to hydrogen.

The Ru(II)-H and water promoted asymmetric cleavage of 2,2'-pyridil to pyridine-2-carbaldehyde and unprecedented picolinic acid anion radical (PyCOOH(-)˙) complexes, which in solution produce H2 gas and diamagnetic picolinate complexes of ruthenium(II) in moderate yields, is reported.

9,10-phenanthrenesemiquinone radical complexes of ruthenium(III), osmium(III) and rhodium(III) and redox series.

Reactions of 9,10-phenanthrenequinone (PQ) in toluene with [M(II)(PPh3)3X2] at 298 K afford green complexes, trans-[M(PQ)(PPh3)2X2] (M = Ru, X = Cl, 1; M = Os, X = Br, 2) in moderate yields. Reaction of anhydrous RhCl3 with PQ and PPh3 in boiling ethanol affords the dark brown paramagnetic complex, cis-[Rh(PQ)(PPh3)2Cl2] (3) in good yields. Diffusion of iodine solution in n-hexane to the trans-[Os(PQ) (PPh3)2(CO)(Br)] solution in CH2Cl2 generates the crystals of trans-[Os(PQ)(PPh3)2(CO)(Br)](+)I3(-), (4(+))I3(-)), in lower yields.

Stabilization of oxidovanadium(IV) by organic radicals.

o-Imino-p-R'-benzosemiquinone anion radical (L(R')(IS)(˙-)) complexes of oxidovanadium(IV) of type [(L(1)(R-))(VO(2+))(L(R')(IS)(˙-))] (R = H, R' = H, 1; R = H, R' = -CMe(3), 2; R = -CMe(3), R' = H, 3 and R = -CMe(3), R' = -CMe(3), 4) incorporating the redox-innocent tridentate NNO-donor L(1)(R-) ligands (L(1)(R)H = 2,4-di-R-6-{(2-(pyridin-2-yl)hydrazono)methyl}phenol) were isolated and substantiated by elemental analyses, IR, mass, NMR and UV-vis spectra including the single crystal X-ray structure determinations. The V-O(phenolato) (cis to the V=O) lengths spanning 1.905(3)-1.

Electronic structures of ruthenium and osmium complexes of 9,10-phenanthrenequinone.

The reaction of 9,10-phenanthrenequinone (PQ) with [M(II)(H)(CO)(X)(PPh(3))(3)] in boiling toluene leads to the homolytic cleavage of the M(II)-H bond, affording the paramagnetic trans-[M(PQ)(PPh(3))(2)(CO)X] (M = Ru, X = Cl, 1; M = Os, X = Br, 3) and cis-[M(PQ)(PPh(3))(2)(CO)X] (M = Ru, X = Cl, 2; M = Os, X = Br, 4) complexes. Single-crystal X-ray structure determinations of 1, 2·toluene, and 4·CH(2)Cl(2), EPR spectra, and density functional theory (DFT) calculations have substantiated that 1-4 are 9,10-phenanthrenesemiquinone radical (PQ(•-)) complexes of ruthenium(II) and osmium(II) and are defined as trans-[Ru(II)(PQ(•-))(PPh(3))(2)(CO)Cl] (1), cis-[Ru(II)(PQ(•-))(PPh(3))(2)(CO)Cl] (2), trans-[Os(II)(PQ(•-))(PPh(3))(2)(CO) Br] (3), and cis-[Os(II)(PQ(•-))(PPh(3))(2)(CO)Br] (4). Two comparatively longer C-O [average lengths: 1, 1.

Unsymmetrical diimine chelation to M(II) (M=Zn, Cd, Pd): atropisomerism, pi-pi stacking and photoluminescence.

Three types of atropisomeric unsymmetrical diimine complexes, tetrahedral (L(R)(Φ))MX(2) (M = Zn, Cd; X = Cl, Br; R = Me, CMe(3), OH, OMe, Cl; 1a-k, type-I), tetrahedral (L(Me2)(Φ))ZnBr(2) (2, type-II) and square planar (L(OH)(ϕ))PdCl(2) (3, type-III) with different photoluminescence properties, have been reported (L(R)(Φ) = (E)-4-R-N-(pyridine-2-ylmethylene)aniline; Φ = dihedral angle between the diimine unit including the pyridine ring and the phenyl ring planes). In crystals, Φ = 0° for type-I, 90° for type-II and 63° for type-III atropisomers have been confirmed by single crystal X-ray structure determinations of 1c, 1e, 2 and 3·H(2)O isomers. Optimizations of geometries in methanol have established Φ = 28-32° for type-I, 90.

o-Iminobenzosemiquinonate and o-imino-p-methylbenzosemiquinonate anion radicals coupled VO2+ stabilization.

The diamagnetic VO(2+)-iminobenzosemiquinonate anion radical (L(R)(IS)(•-), R = H, Me) complexes, (L(-))(VO(2+))(L(R)(IS)(•-)): (L(1)(-))(VO(2+))(L(H)(IS)(•-))•3/2MeOH (1•3/2MeOH), (L(2)(-))(VO(2+))(L(H)(IS)(•-)) (2), and (L(2)(-))(VO(2+))(L(Me)(IS)(•-))•1/2 L(Me)(AP) (3•1/2 L(Me)(AP)), incorporating tridentate monoanionic NNO-donor ligands {L = L(1)(-) or L(2)(-), L(1)H = (2-[(phenylpyridin-2-yl-methylene)amino]phenol; L(2)H = 1-(2-pyridylazo)-2-naphthol; L(H)(IS)(•-) = o-iminobenzosemiquinonate anion radical; L(Me)(IS)(•-) = o-imino-p-methylbenzosemiquinonate anion radical; and L(Me)(AP) = o-amino-p-methylphenol} have been isolated and characterized by elemental analyses, IR, mass, NMR, and UV-vis spectra, including the single-crystal X-ray structure determinations of 1•3/2MeOH and 3•1/2 L(Me)(AP). Complexes 1•3/2MeOH, 2, and 3•1/2 L(Me)(AP) absorb strongly in the visible region because of intraligand (IL) and ligand-to-metal charge transfers (LMCT). 1•3/2MeOH is luminescent (λ(ext), 333 nm; λ(em), 522, 553 nm) in frozen dichloromethane-toluene glass at 77 K due to π(diimine→)π(diimine)* transition.

Osazone anion radical complex of rhodium(III).

One electron paramagnetic parent osazone complex of rhodium of type trans-Rh(L(NHPh)H(2))(PPh(3))(2)Cl(2) (1), defined as an osazone anion radical complex of rhodium(III), trans-Rh(III)(L(NHPh)H(2)(•-))(PPh(3))(2)Cl(2), 1((t-RhL•)), with a minor contribution (∼2%) of rhodium(II) electromer, trans-Rh(II)(L(NHPh)H(2))(PPh(3))(2)Cl(2), 1((t-Rh•L)), and their nonradical congener, trans-[Rh(III)(L(NHPh)H(2))(PPh(3))(2)Cl(2)]I(3) ([t-1](+)I(3)(-)), have been isolated and are substantiated by spectra, bond parameters, and DFT calculations on equivalent soft complexes [Rh(L(NHPh)H(2))(PMe(3))(2)Cl(2)] (3) and [Rh(L(NHPh)H(2))(PMe(3))(2)Cl(2)](+) (3(+)). 1 is not stable in solution and decomposes to [t-1](+) and a new rhodium(I) osazone complex, [Rh(I)(L(NHPh)H(2))(PPh(3))Cl] (2). 1 absorbs strongly at 351 nm due to MLCT and LLCT, while [t-1](+) and 2 absorb moderately in the range of 300-450 nm, respectively, due to LMCT and MLCT elucidated by TD-DFT calculations on 3((t-RhL•)), [t-3](+), and Rh(I)(L(NHPh)H(2))(PMe(3))Cl (4).

Unsymmetrical diimine complexes of iron(II) and manganese(II): synthesis, structure and photoluminescence of an isomer.

Two bis(unsymmetrical diimine) complexes of (L(NO(2))(ϕ1))(L(NO(2))(ϕ2))M(II)Cl(2) family with M = Fe and Mn, are reported (L(NO(2))(ϕ) = (E)-3-nitro-N-(pyridine-2-ylmethylene)aniline; ϕ = dihedral angle between the diimine unit including pyridine ring and the phenyl ring planes). Pure tcc-(L(NO2)(33.6))(L(NO2)(79.

Electronic structure of the glyoxalbis(2-hydroxyanil) (gha) ligand in [Co(III)(gha)(PPh3)2]+: radical vs. non-radical states.

The synthesis, structure and spectroscopic properties of a complex salt [Co(III)(gha)(PPh3)2][Co(II)Cl3(PPh3)] x C2H5OH (1) are reported; gha = glyoxalbis(2-hydroxyanil). This is the first single crystal X-ray structure of a (gha)2- complex with a transition element. Though the determined bond parameters and UV-Vis spectroscopic data correlate well with a diradical description for the cation in 1, detailed electronic structure calculations using density functional theory confirm that [Co(gha)(PPh3)2]+ can be described as a closed shell singlet species which nevertheless displays an interesting electronic structure with significant electron transfer to the formally unoccupied LUMO of the square planar [Co(gha)]+ fragment.

First ruthenium complex of glyoxalbis(N-phenyl)osazone (L(NHPh)H(2)): synthesis, x-ray structure, spectra, and density functional theory calculations of (L(NHPh)H(2))Ru(PPh(3))(2)Cl(2).

The first ruthenium complex containing the parent osazone ligand, glyoxalbis(N-phenyl)osazone (L(NHPh)H(2)), is reported. The complex (L(NHPh)H(2))Ru(PPh(3))(2)Cl(2) (1) was characterized with mass, IR, (1)H NMR, and UV-vis spectroscopy as well as with theoretical calculations. Density functional theory calculations on the model compound (L(NHPh)H(2))Ru(PMe(3))(2)Cl(2) (2) reproduce the geometrical features observed for 1 and verify that it formally contains a ruthenium(II) metal center coordinated by a neutral osazone.