Two isostructural tellurite phosphates Ni_(2)M^(Ⅱ)Te^(Ⅳ)_(2)O_(2)(PO_(4))_(2)(OH)_(4)(M^(Ⅱ)=Ni,Zn)have been synthesized via hydrothermal method.Both of them crystalize in monoclinic space group C2/m(No.12).For Ni_(2)ZnTe^(Ⅳ)_(2)O_(2)(PO_(4))_(2)(OH)_(4),a=19.3247(10),b=5.9697(3),c=4.7737(2)Å,β=103.637(5)°,V=535.18(5)Å^(3),Z=2,M_(r)=727.94,S=1.103,D_(c)=4.517 g·cm^(-3),μ(Mo Kα)=11.434 mm^(-1) and F(000)=672,the final R=0.0369and wR=0.1086 for 639 observed reflections with I>2σ(I).The crystal structure of Ni_(2)M^(Ⅱ)Te^(Ⅳ)_(2)O_(2)(PO_(4))_(2)(OH)_(4)(M^(Ⅱ)=Ni,Zn)features a 3D framework composed of[Ni_(2)O_(2)(PO_(4))_(2)]^(6-)layers interconnected by[MTe_(2)O_(2)(OH)_(4)]^(2+)single chains.Different magnetic susceptibility results at low temperature of the two title compounds confirm that Zn(1)completely occupies the Ni(2)position but not partially substitutes both Ni(1)and Ni(2)position atoms.Additionally,the acentric TeO_(3)(OH)_(2) tetragonal pyramids are aligned in an antiparallel manner,resulting in the crystallization of centrosymmetric(C2/m)crystal structure instead of the non-centrosymmetric crystal structure.The investigation of the origin of centrosymmetric crystal structure with strong dipole moment units provides deeper understanding for future rational design for non-centrosymmetric crystal structure.
A vanadyl phosphate containing a new member of tancoite-like single chain,(DAPH2)[VIVO(HPO4)2]·xH2O(x≈0.2,DAP=1,3-diaminopropane,C3H10N2),has been synthesized under hydro(solvo)thermal conditions.It crystallizes in orthorhombic space group P21212(No.18)with a=7.1730(14),b=19.252(4),c=8.6557(17),Z=4,V=1195.3(4)3,C3H14.38N2P2VO9.19,Mr=338.47,Dc=1.881 g/cm3,μ(MoKα)=1.138 mm–1and F(000)=692.The final full-matrix least-squares refinement converged to R=0.0408,wR=0.1046 for 2498 observed reflections with I>2(I)and R=0.0456 and wR=0.1080 for all data(2750)and S=1.001.Its one-dimensional structure consists of tancoite-like1{VIVO(HPO4)2}2–single chains surrounded by DAPH22+ions and water molecules.The single chain is built from trans-corner-sharing octahedral{VIV=O···VIV}backbone loop-branched by HPO4groups like staple forming a new member of tancoite single chain.Due to the special coordination of VIVO6,the1{VO(HPO4)2–}chain adopts a larger M–O–M angle(V–O–V=135o)than those of tancoite chains reported before.The corner-sharing linear{VIV=O···VIV}chain structure also leads to a one-dimensional weak antiferromagnetic interaction at low temperature.The magnetic measurements confirm the 4+valence state of vanadium.IR and TG results of the title compound are also discussed.
Two new alkali metal germanophosphates,namely,Na_(3)[Ge(OH)(PO_(4))_(2)]·2 H2 O and Li_(2)Na[GeO(HPO_(4))(PO_(4))],have been prepared by solvothermal method,and their crystal structures were determined by single-crystal X-ray diffraction.The title two compounds crystalize in the same orthorhombic space group Pbcm(No.57)and feature similar chain-like structure which is built from zig-zag GeO_(6) octahedral thread loop branched by PO_(4) tetrahedra.For Na_(3)[Ge(OH)(PO_(4))_(2)]·2 H_(2)O,a=10.1650(9),b=13.1975(12),c=6.9751(7)Å,V=935.73(15)Å^(3),Z=4,R=0.0356 and wR=0.1109;and for Li_(2)Na[GeO(HPO_(4))(PO_(4))],a=6.9855(5),b=14.5809(18),c=6.6620(5)Å,V=678.56(11)Å^(3),Z=4,R=0.0286,and w R=0.0762.The partial substitution of Na ions by Li ions not only significantly influences the total structural features and the water molecule contents,but also impacts on their thermal stabilities.Li_(2)Na[GeO(HPO_(4))(PO_(4))]is thermally stable up to 400℃,whereas only 150℃ for Na_(3)[Ge(OH)(PO_(4))_(2)]·2 H2 O.
A new modification of tellurite phosphate, β-Te_3O_3(PO_4)_2, has been synthesized under hydrothermal conditions and its crystal structure was determined by single-crystal X-ray diffraction. It crystallizes in the monoclinic space group P2_1/n(No. 14), with a = 11.115(5), b = 4.7033(19), c = 17.287(7) ?, β = 106.086(5)°, V = 868.3(6) ?~3, Z = 4, P_2 Te_3 O_(11), M_r = 620.74, D_c = 4.748 g/cm^3, μ(Mo Kα) = 10.438 mm^(–1) and F(000) = 1096. The final full-matrix least-squares refinement converged to R = 0.0227, wR = 0.0534 for 1984 observed reflections with I > 2σ(I), and R = 0.0240, w R = 0.0540 for all data(2070) and S = 1.117. β-Te_3O_3(PO_4)_2 is polymorphic with the known α-Te_3O_3(PO_4)_2(Weil H. M. et al. Z. Anorg. Allg. Chem. 2003, 629, 1068-1072). The crystal structure of β-Te_3O_3(PO_4)_2 features a three-dimensional(3D) network composed of Te_6 O_(22)^(20)-hexanuclear clusters interconnected by PO_4 groups. Te_6 O_(22) hexanuclear cluster is built from three Te_2 O_8 dimers(edge-sharing TeO_5 square pyramids) linked to each via sharing O-corners. The structure difference between α-and β-forms of Te_3O_3(PO_4)_2 lies in the polymerization of tellurite oxides Te_nO_m. 1D infinite ~1_∞{[Te_3 O_(11)]^(10-)} single chains are presented in α-Te_3O_3(PO_4)_2, while 0D discrete Te_6 O_(22) hexanuclear clusters are observed for β-Te_3O_3(PO_4)_2. Moreover, thermal analyses, infrared spectra and UV-Vis-NIR diffuse reflectance are also presented.
