viABSTRACTThe crystal structure of non-centrosymmetric 6-(2-fluorobenzylidene)-2-[1-(2-fluoro-4-biphenyl)ethyl]-thiazolo[3,2-b][1,2,4]-triazol-5(6H)-one,(C25H17F2N3OS), crystal and centrosymmetric 3-[4-(4-fluorophenyl)piperazin-1-ylmethyl]-5-methyl-1,3-benzoxazol-2(3H)-one, (C19H20FN3O2)(I) and 3-[4-(2-fluorophenyl)piperazin-1-ylmethyl]-5-methyl-1,3-benzoxazol-2(3H)-one,(C19H20FN3O2)(II), have been determined by x-ray diffraction method in thisstudy.(C25H17F2N3OS), Orthorhombic , Fdd2, a= 24.059(3)Ã, b= 54.213(5)Ã, c=6.5223(5)Ã, α= 90°, β= 90, γ= 90°, V= 8507.3(2)Ã3, Z=16, Dx= 1.391 Mg/m3,λ(MoKα)= 0.71073Ã, μ= 0.19mm-1, T= 293(2)°K, R= 0.037, RÏ= 0.069, S= 0.67,F(000)= 291, Flack(x)= 0.1(14).The 6-(2-fluorobenzylidene)-2-[1-(2-fluoro-4-biphenyl)ethyl]-thiazolo[3,2-b][1,2,4]-triazol-5(6H)-one, (C25H17F2N3OS), crystal was synthesized from 6-(benzylidene)thiazolo[3,2-b][1,2,4]-triazol-5(6H)-one. Although the fusedthiazolo[3,2-b][1,2,4]-triazole system in the structure is planar, hydrogen bondinteractions are present between molecules of the crystal. The structurecontains absolute structure parameter (Flack Parameter) due to its non-centrosymmetry.(C19H20FN3O2)(I), 3-[4-(4-Fluorophenyl)piperazin-1-ylmethyl]-5-methyl-1,3-benzoxazol-2(3H)-one, Monoclinic, P21/c, a= 8.1788(6)Ã, b= 6.1512(4)Ã, c=34.090(3)Ã, β= 103.067(7)°, α= γ = 90°, V= 1670.6(2)Ã3, Z=4, Dx= 1.357 Mg/m3,λ(MoKα)= 0.71073Ã, μ= 0.10mm-1, T= 293(2)°K, R= 0.080, RÏ= 0.250, S= 1.07,F(000)= 240.(C19H20FN3O2)(II), 3-[4-(2-fluorophenyl)piperazin-1-ylmethyl]-5-methyl-1,3-benzoxazol-2(3H)-one, Monoklinik, P21/c, a= 15.7467(10)Ã, b= 9.5470(4)Ã,c= 11.4779(6)Ã, β= 91.422(5)°, α= γ = 90°, V= 1724.98(16)Ã3, Z=4, Dx= 1.314Mg/m3, λ(MoKα)= 0.71073Ã, μ= 0.09mm-1, T= 293(2)°K, R= 0.041, RÏ= 0.124,S= 1.07, F(000)= 246.Both (C19H20FN3O2)(I), (C19H20FN3O2)(II), crystals are composed ofplanar benzoxazolinone ring systems, with slightly different C-N bond distances.These structures have intermolecular interactions.viiKeywords: Centrosymmetry, non- centrosymmetry, absolute structure, FlackParameter.

ivÖZETBu çalışmada merkezi simetrik olmayan (C25H17F2N3OS), 6-(2-florobenzildien)-2-[1-(2-floro-4-bifenil)etil]-tiyazol[3,2-b][1,2,4]-triazol-5(6H)-on,kristali ile merkezi simetrik yapıya sahip olan, (C19H20FN3O2) (I), 3-[4-(4-florofenil)-1-piperazinil-metil]-5-metil-1,3-benzoksazol-2(3H)-on, (C19H20FN3O2)(II), 3-[4-(2-florofenil)-1-piperazinil-metil]-5-metil-1,3-benzoksazol-2(3H)-onkristallerinin yapısı x-ışını difraksiyonu yöntemiyle analiz edilmiştir.(C25H17F2N3OS), Ortorombik, Fdd2, a= 24.059(3)Ã, b= 54.213(5)Ã, c=6.5223(5)Ã, α= 90°, β= 90°, γ = 90°, V= 8507.3(2)Ã3, Z=16, Dx= 1.391 Mg/m3,λ(MoKα)= 0.71073Ã, μ= 0.19mm-1, T= 293(2)°K, R= 0.037, RÏ= 0.069, S= 0.67,F(000)= 291, Flack(x)= 0.1(14) .(C25H17F2N3OS), kristali 6-(benzildien)tiyazol[3,2-b][1,2,4]-triazol-5(6H)-one yapısından sentezlenmiştir. Yapıda bulunan birleşik tiyazol[3,2-b][1,2,4]-triazol sistemi düzlemsel olmakla birlikte, kristalin molekülleri arasında hidrojenbağı etkileşimleri mevcuttur. Yapı merkezi simetrik olmamasından ötürü mutlakyapı parametresi olarak isimlendirilen Flack parametresini (değerini)içermektedir.3-[4-(4-florofenil)-1-piperazinil-metil]-5-metil-1,3-benzoksazol-2(3H)-one,(C19H20FN3O2)(I), Monoklinik, P21/c, a= 8.1788(6)Ã, b= 6.1512(4)Ã, c=34.090(3)Ã, β= 103.067(7)°, α= γ = 90°, V= 1670.6(2)Ã3, Z= 4, Dx= 1.357 Mg/m3,λ(MoKα)= 0.71073Ã, μ= 0.10mm-1, T= 293(2)°K, R= 0.080, RÏ= 0.250, S= 1.07,F(000)= 240.3-[4-(2-florofenil)-1-piperazinil-metil]-5-metil-1,3-benzoksazol-2(3H)-one,(C19H20FN3O2)(II), Monoklinik, P21/c, a= 15.7467(10)Ã, b= 9.5470(4)Ã, c=11.4779(6)Ã, β= 91.422(5)°, α= γ = 90°, V= 1724.98(16)Ã3, Z=4, Dx= 1.314Mg/m3, λ(MoKα)= 0.71073Ã, μ= 0.09mm-1, T= 293(2)°K, R= 0.041, RÏ= 0.124,S= 1.07, F(000)= 246.(C19H20FN3O2)(I), (C19H20FN3O2)(II), kristallerinin her ikiside C-N bağuzunlukları birbirinden farklı olmayan, esasen düzlemsel benzoksazoline halkasisteminden meydana gelmişlerdir. Bu yapılar molekül arası etkileşimesahiptirler.vAnahtar Kelimeler: Merkezi simetrik, merkezi simetrik olmayan, mutlak yapı,Flack Parametresi.