The Crystal Structure of Biphenyltetracarboxylic Dianhydride Isomers

2,2',3,3'-Biphenyltetracarboxylic dianhydride (2,2',3,3'-BPDA), C16H6O6, Mr=294.21, monoclinic, P21/c, a=11.694(2)(A), b=8.111(2), c=13.494(3), β=103.47(3)°, V=1244.7(4)3, Z=4, Dc=1.570 g/cm3, F(000)=450, MoKα radiation(λ=0.71073(A)), μ(MoKα)=0.092 mm-1, R=0.0329 for 2180 observed reflections [I>2σ(I)]. 3,3',4,4'-Biphenyltetracarboxylic dianhydride (3,3',4,4'-BPDA), C16H6O6, Mr=294.21, monoclinic, P21/n, a=6.8720(14), b=5.1870(10), c=17.288(4)(A), β=94.96(3)°, V= 613.9(2)(A)3, Z=2, Dc=1.592 gcm-3, F(000)=300 , μ(MoKα)=0.125mm-1, R=0.0331 for 1079 observed reflections[I>2σ(I)]. The dianhydride isomers have different symmetry caused by alternating two anhydride group positions and the dihedral angle between the two phenyl rings are 62.9°for 2,2',3,3',-BPDA and 0°for 3,3',4,4'-BPDA respectively.