Crystal Structures of Incommensurately Modulated Ln(PO3)3 (Ln = Tb-Yb) and Commensurate Gd(PO3)3 and Lu(PO3)3
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- 作者：Henning A. Hö ; ppe ; Stefan J. Sedlmaier
- 刊名：Inorganic Chemistry
- 出版年：2007
- 出版时间：April 30, 2007
- 年：2007
- 卷：46
- 期：9
- 页码：3467 - 3474
- 全文大小：276K
- 年卷期：v.46,no.9(April 30, 2007)
- ISSN：1520-510X
文摘
The crystal structure of the late lanthanoids' catena-polyphosphates Ln(PO3)3 (Ln = Tb-Yb) is incommensuratelymodulated (Dy(PO3)3: space group Cc(0
hars/beta2.gif" BORDER=0 ALIGN="middle">0)0; Z = 4; a = 1417.4(4), b = 670.96(14), c = 1009.5(3) pm; hars/beta2.gif" BORDER=0 ALIGN="middle"> =127.62(2)
, q = 0.364b*; Rall = 0.057, wRall = 0.071; 293 K) and consists of infinite chains of corner-sharing PO4tetrahedra. The cations are coordinated 6-fold in an almost octahedral arrangement over the whole modulationperiod. All atoms comprise a sinoidal positional modulation. The basic structure can be derived from a fcc packingwhich explains the pseudo-face-centering observed in the diffraction patterns. The crystal structure of Lu(PO3)3 isisotypic with C-type phosphates (Cc; Z = 12; a = 1397.2(1), b = 2001.8(2), c = 995.56(9) pm; hars/beta2.gif" BORDER=0 ALIGN="middle"> = 127.351(6);R1 = 0.042, wR2 = 0.097, 293 K), and Gd(PO3)3 crystallizes in a new structure type (I2/a; Z = 16; a =2601.7(2), b = 1351.1(1), c = 1008.4(1) pm; hars/beta2.gif" BORDER=0 ALIGN="middle"> = 119.311(6); R1 = 0.039, wR2 = 0.092; 293 K). Both can bedescribed in terms of superstructures of the basic structure unit cell of the incommensurate phases, and thus, aconsistent structural description of many polyphosphates is provided. Tb(PO3)3 was obtained as single phase adoptinga novel synthesis under reducing conditions. The absence of an inversion center in the incommensurate phasesand Lu(PO3)3 was proved by a SHG experiment. The vibrational spectra are also discussed.
hars/beta2.gif" BORDER=0 ALIGN="middle">0)0; Z = 4; a = 1417.4(4), b = 670.96(14), c = 1009.5(3) pm; hars/beta2.gif" BORDER=0 ALIGN="middle"> =127.62(2), q = 0.364b*; Rall = 0.057, wRall = 0.071; 293 K) and consists of infinite chains of corner-sharing PO4tetrahedra. The cations are coordinated 6-fold in an almost octahedral arrangement over the whole modulationperiod. All atoms comprise a sinoidal positional modulation. The basic structure can be derived from a fcc packingwhich explains the pseudo-face-centering observed in the diffraction patterns. The crystal structure of Lu(PO3)3 isisotypic with C-type phosphates (Cc; Z = 12; a = 1397.2(1), b = 2001.8(2), c = 995.56(9) pm; hars/beta2.gif" BORDER=0 ALIGN="middle"> = 127.351(6);R1 = 0.042, wR2 = 0.097, 293 K), and Gd(PO3)3 crystallizes in a new structure type (I2/a; Z = 16; a =2601.7(2), b = 1351.1(1), c = 1008.4(1) pm; hars/beta2.gif" BORDER=0 ALIGN="middle"> = 119.311(6); R1 = 0.039, wR2 = 0.092; 293 K). Both can bedescribed in terms of superstructures of the basic structure unit cell of the incommensurate phases, and thus, aconsistent structural description of many polyphosphates is provided. Tb(PO3)3 was obtained as single phase adoptinga novel synthesis under reducing conditions. The absence of an inversion center in the incommensurate phasesand Lu(PO3)3 was proved by a SHG experiment. The vibrational spectra are also discussed.