Crystal structure of ethanolato-dibenzoylmethanato-(R,R-dibenzoylstilbenediamine)-nitratonickel(II), Ni(C2H5OH)(C15H11O2)(C28H26N2)(NO3)

Abstract

Source of materialThe title compound was prepared by adding 0.393 gofdibenzoylstilbenediamine (dbstien) obtained according to the published method [1] to 0.291 gofNi(NO 3 ) 2 · 6H 2 Odissolved in 10 ml of ethanol followed by the addition of 0.224 gofdibenzoylmethane and 0.07 go fK OH, and stirred for 60 minutes. The resulting bluish-green solution was filtered, allowed to stand. Green crystals suitable for X-ray diffraction experiments were obtained by slow vapour diffusion of diethyl ether into the ethanol solution. Experimental detailsThe hydrogen atoms bound to carbon atoms were fixed at calculated positions with d(C-H) =0.97 Å, d(C=C-H) =1.08 Å.The hydrogen bound to O6 was not located in the difference Fourier map due to the probable disorder over two sites. DiscussionStilbenediamine containing metal complexes of copper, nickel and zinc have been catching attention due to their catalytic activity in asymmetric syntheses [2][3][4][5][6][7][8][9]. Recently achiral copper catalyst having dibenzoylstilbene as its ligand has been developed to achieve enantioselective Mannich-type reactions of Nacylimino esters with, for example, alkyl vinyl ethers to afford the corresponding N-acylated amino acid derivatives [7]. To date, only af ew structures of these complexes have been reported, hence our interest to isolate, crystallize and to determine the molecular structure of the nickel complex presented here. The crystal structure consists of asymmetric units containing one Ni complex, [Ni(C 2H6O)(C15H11O2)(C28H28N2)(NO3)]. The central nickel atom has as lightly distorted octahedral coordination, with the angles around nickel ranging from 81.9(2)°to 103.1(2)°,and 172.8(2)°to 177.1(2)°,respectively. The average Ni-Ndistance (Ni-N2, Ni-N3) is 2.091(5) Å,which is in the normal bond range for an octahedral Ni complex. The respective Ni-O dbm distances Ni-O4 and Ni-O5 are 1.976(4) Å and 2.033(4) Å which reflect the relative trans effect exhibited by N3 as opposed to O6 (ethanol), making the former distance shorter. The nitrate molecule coordinates Ni at the expected distance Ni-O1 of 2.179(4) Å.T he dibenzoylstilbene and dibenzoylmethanate (dbm) bidentate chelate planes are virtually perpendicular to each other. The atomic arrangement around atoms C16 and C17 reflects the R,R configuration of dibenzoylstilbene of the overall absolute molecular structure. Finally, the oxygen of the ethanol molecule locates at the normal distance of 2.083(4) Å from the nickel centre.