trans-Bis(3-hydroxy-2-phenyl-4H-1-benzopyran-4-onato)bis(pyridine)nickel(II)

Abstract

and Ni--N distances are 2.067(2), 2.023 (2) and 2.180 (2)~,, respectively. All the C--C bond distances are normal with values between 1.366 (3) and 1.406 (4)A, except those which are close to the coordinated C--O bonds: C(1)---C(2), C(2)---C(3) and C(9)--C(10) are 1.457 (4), 1.445 (3) and 1.462 (4) A., respectively. All rings are almost planar, except those involving coordinated O atoms. The dihedral angles between the flavonato planes and the pyridyl ligands are Acta Crystallographica Section C ISSN 0108-2701 ©1995 [Ni(C15 H9 03 )2 (C5 H5 N)2 ]quite large with values of ca 84 ° . The angles between the planes in the hydroxyflavone ligand are less than 10 ° . CommentThe structures of coordinated ligands containing N and O atoms bonded to nickel provide important information on metalloenzyme systems. Complexes of Ni H with ligands such as aminocyclohexanecarboxylate (Haendler, 1993), hexafluoroacetonate (Polam & Porter, 1992), salicyaldehydate (Stewart, Lingafelter & Breazeale, 1961), acetylacetonate and tetramethylethylenediamine (Yamada, Hori & Fukuda, 1993), benzenedicarboxylate and 2,2'-bipyridyl (Poleti, Karanovic & Prelesnik, 1990), glycinate and 2,2'-bipyridyl (Z~ik, Gtowiak, Kamenffzek & B~ezina, 1990), carboxylates and silane carboxylate (Morooka et al., 1992) have been reported. Although the structure of flavonol chelated to copper has been reported (Speier, Fiilop & Parkanyi, 1990), little information is available on the analogues of nickel. An ethanolic solution of the triethylammonium salt of the 3-hydroxyflavonato anion reacts with NiC12.6H20 to form [Ni(H20)2(flv)2], which, on heating with excess pyridine under reflux, produces trans-[Ni(py) The crystal structure of (I) is shown in Fig. 1. The Ni atom is octahedrally surrounded by two trans py and two chelating fly ligands. All the trans O--Ni--O and N--Ni--N bond angles are exactly 180 ° because the Ni atom lies on a centre of symmetry. The O---Ni--N angles are close to 90 ° (Table 2). However, the angle subtended by both chelating O atoms at the nickel centre is found to be 81.0(1) °. This value is consistent with the values reported for other five-membered chelates, such as chelates of Ni n with 1-aminocyclohexanecarboxylato and Cu I with 3-hydroxyflavonato (Speier et al., 1990) which have values of 81.3 (2) and 79.2 (3) ° , respectively. The 0(2)--crC ( The C--C bond distances in the hydroxyflavonato moiety further emphasize the canonic nature of the pyrone ring. The C(9)---C(1) and C(3)--C(8) bonds of 1.385 (3) and 1.389 (3)A,, respectively, are shorter than C(1)---C(2) which is 1.457 (4)A in length. The C----C distances in the pyridyl ligands are normal with a mean of 1.376 (6)A,. The N---C distances are slightly shorter than the C--C bond.The least-square planes are almost coplanar except for plane 1 containing Ni (1) ExperimentalThe green rhombohedral product of the reaction described in the Comment was recrystallized from hot acetonitrile. The crystal density Dm was measured by flotation in CCl4/hexane. 1.406 (4) C(4)---C(57 1.366 (3...

2,2-Difluoro-4-phenyl-1,3,2-dioxaborolo[4,5-c]chromen-5-ium-2-ide

“…The canonical structure of the title compound suggests that the phenylchromenium core of the molecule is aromatic. This is confirmed by analysis of the bond lengths and angles, as well as comparison of the structure determinated here with the structures of selected compounds containing flavonol units (Farina et al, 1995;Belogh-Hergovich et al, 1999;Okabe et al, 2003;Kaizer et al, 2007). Furthermore, the average deviation from planarity of the phenylchromenium core is 0.0215 (2) and that of the molecule's skeleton is 0.0373 (2).…”

“…For general background to 3-hydroxy-2-phenyl-4H-chromene-4-one (flavonol) and its derivatives, see: Kukharenko & Avramenko (2001); Petković et al (2010); Roshal et al (1998Roshal et al ( , 2003; Sytnik et al (1994). For related structures, see: Belogh-Hergovich et al (1999); Farina et al (1995); Kaizer et al (2007); Okabe et al (2003). For intermolecular interactions, see: Choudhury & Guru Row (2004); Hunter et al (2001); Novoa et al (2006); Thalladi et al (1998).…”

“…It appears that not complexation but condensation of the two reagents, accompanied by the release of HF, takes place (Kukharenko & Avramenko, 2001) and a molecule of a formally zwitterionic canonical structure was produced. Crystal structures of various flavonol complexes have so far been reported (Farina & Yamin, 1995;Belogh-Hergovich et al, 1999;Okabe et al, 2003;Kaizer et al, 2007), but none of them have contained boron.…”

Overview of the Antioxidant and Anti-Inflammatory Activities of Selected Plant Compounds and Their Metal Ions Complexes

“…Among all the complexes, there are only a few bis complexes: [Cu(Flav- O , O ) 2 (py- N , N ) 2 ] [ 269 ], [Cu(Flav- O , O ) 2 ] [ 270 ] and [Fe(Flav- O , O ) 2 Cl,CH 3 OH] [ 271 ]–with additional Cl and CH 3 OH ligands [Ni(Flav- O , O ) 2 (py- N ) 2 ] [ 272 ] with pyridine ligands and one tris complex [Fe(Flav- O , O ) 3 ] [ 273 ]. Other co-ligands bound to M may be divided into 10 categories: O -donors such as H 2 O, ClO 4 , NO 3 , dimethylsulfoxide (DMSO), 2-(2-hydroxyphenyl)-2-oxoacetic acid; P -donors such as PPh 3 ; F -donors such as BF 4 ; N -donors including pyridine(py); N , N -donors ((2,2′bipyridine (bipy), N , N , N ′, N ′-tetramethylenediamine (temed)); N , N , N -donor (bis(pyridin-2-ylmethyl)-l2-azane (aza), 1,4,7-tribenzyl-1,4,7-triazonane (azon), N1-(3-(dimethylamino)propyl)-N3,N3-dimethylpropane-1,3-diamine (dpp), tri(1 H -pyrazol-1-yl)borane (pyb), tris(1-ethyl-4-methyl-1 H -imidazol-2-yl)phosphane (trim), tris(pyridin-2-ylmethyl)amine (tripy), N , N , N (1 Z ,3 Z )- N , N ′′′-di(pyridin-2-yl)-2l2-isoindoline-1,3-diimine (dipyim)); N , N , N , N ,-donor tris(pyridin-2-ylmethyl)amine (tripy); N , O -donors:(E)-1-(2-(l1-oxidaneyl)phenyl)- N -phenylmethanimine (oxphen); N , N , N , O -donor (2-((bis(pyridin-2-ylmethyl)amino)methyl)phenyl)(l1-oxidaneyl)methanone (azam); N , N , O , O ,-donor (1E,1′E)- N , N ′-(ethane-1,2-diyl)bis(1-(2-(l1-oxidaneyl)phenyl)methanimine) (etoxian) ( Figure 12 ).…”

“…Similar co-ligands are in complexes of general formula [Ni(Flav- O , O )(azam- N , N , N , O )] [ 302 ] where in [ 303 ] there is Br-azam co-ligand, while in [ 299 ] NO 2 -azam co-ligand with two water molecules beyond the coordination sphere. Other six-coordinated complexes: [Ni(Flav- O , O )(tripy- N , N , N , N )] [ 279 ], [Ni(Flav- O , O )(H 2 O) 4 ] [ 303 ] and [Ni(Flav- O , O ) 2 (py- N ) 2 ] [ 272 ] have the following coordination mode: O , O -bidentate and N , N , N , N -tetradnetate in [ 279 ] O , O bidentate and monodentate four H 2 O in [ 303 ] and two O , O bidentate Flav ligand with two monodentate N -pyridine ligands in [ 269 ]. Complex [Ni(Flav- O , O )(tripy- N , N , N ,] [ 279 ] has the same co-ligand as [ 279 ]; however, it is five-coordinated and tripy ligand is coordinated by three nitrogens.…”