bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cs4Ge9·en: A Novel Compound with [Ge9]4− Clusters – Synthesis, Crystal Structure and Vibrational Spectra
Authors: Carrillo‐Cabrera Wilder , Aydemir Umut , Somer Mehmet , Kircali Aslihan , Fässler Thomas F. , Hoffmann Stephan D. 
Published: July 2007

AbstractRed‐orange prismatic crystals of Cs4Ge9·en (en = ethylenediamine) were obtained via metathesis reaction of an en solution of K4Ge9 with a large excess of CsI. The compound is very sensitive to air and moisture. Cs4Ge9·en is not isotypic to Rb4Ge9·en and crystallizes in a new structure type (monoclinic, space group P21/c (No. 14); a = 16.757(3), b = 16.462(3), c = 15.657(2) Å, β = 90.37(1)°; Z = 8; Pearson code mP200). The crystal structure comprises two types (A and B) of discrete [Ge9]4− units arranged in the motif of a distorted hexagonal close‐packing (h.c.p.). In this h.c.p. framework, each tetrahedral hole is filled by one Cs atom and each larger octahedral hole is filled by a group of one en and two Cs atoms. The topology of the two crystallographically distinct [Ge9]4− clusters corresponds to distorted, monocapped tetragonal antiprisms with bond lengths varying in the range 2.551–2.848Å (type A cluster) or in the range 2.538–2.975Å (less regular type B cluster). According to the DTA and TG measurements, Cs4Ge9·en decomposes at 378 K under liberation of gaseous ethylenediamine yielding Cs4Ge9. The Raman spectra of the title compound were interpreted based on the idealized C4ν symmetry of an isolated [Ge9]4− cluster. The characteristic breathing mode was localized at 222 cm−1. The results are analyzed and discussed in context with those of the previously reported compounds Cs4Ge9, K4Ge9 and Rb4Ge9·en.
A Convenient, Selective Synthesis of Bis[2,4‐bis(trifluoromethyl)phenyl]phosphane Derivatives Starting from 1,3‐Bis(trifluoromethyl)benzene
Authors: Hoge Berthold , Kurscheid Boris , Peuker Sebastian , Tyrra Wieland , Fischer Hendrik T. M. 
Published: July 2007

AbstractThe reaction of the sterically shielded phosphane derivative, dichlorodiethylaminophosphane, Cl2PNEt2, with an excess of a mixture of 2,6‐bis(trifluoromethyl) and 2,4‐bis(trifluoromethyl)phenyl lithium gives bis[2,4‐bis(trifluoromethyl)phenyl]diethylaminophosphane, [2,4‐(CF3)2C6H3]2PNEt2, in 72 % yield as a colourless solid, while 2,6‐bis(trifluoromethyl)phenyl lithium remains unchanged in solution. The amino derivative crystallizes in the monoclinic space group P21/c (a 869.2(1), b 1857.4(1), c 1357.6(1) pm, β 100.57(4)°, Z = 4).Treatment of [2,4‐(CF3)2C6H3]2PNEt2 in CHCl3 solution with conc. HCl allows the synthesis of [2,4‐(CF3)2C6H3)]2PCl. [2,4‐(CF3)2C6H3]2PCl reacts with H2O in THF solution with quantitative formation of the corresponding secondary phosphane oxide. To obtain bis[2,4‐bis(trifluoromethyl)phenyl]phosphinic acid, [2,4‐(CF3)2C6H3]2P(O)OH, quantitatively, a CHCl3 solution of [2,4‐(CF3)2C6H3]2P(O)H, has to be stirred in an NO2 atmosphere. The phosphinic acid crystallizes is the triclinic space group $\rm P{\bar 1}$ (a 754.2(1), b 927.6(2), c 1305.5(2) pm, α 85.11(2)°, β 75.45(1)°, γ 79.99(2)°, Z = 2). From the reaction of the phosphinic acid with either elemental sodium or with cyanide salts, the corresponding phosphinate salts are obtained in an almost quantitatively yield.
Intermetallic Phases in the Ca‐Cu‐Sn System
Authors: Pani Marcella , Merlo Franco , Fornasini Maria L. 
Published: July 2007

AbstractTwelve ternary alloys in the Ca‐Cu‐Sn system were synthesized as a test on the existing phases. They were prepared from the elements sealed under argon in Ta crucibles, melted in an induction furnace and annealed at 700 °C or 600 °C. Four ordered compounds were found: CaCuSn (YbAuSn type), Imm2, a = 4.597(1) Å, b = 22.027(2) Å, c = 7.939(1) Å, Z = 12, wR2 = 0.080, 1683 F2 values; Ca3Cu8Sn4 (Nd3Co8Sn4 type), P63mc, a = 9.125(1) Å, c = 7.728(1) Å, Z = 2, wR2 = 0.087, 704 F2 values; CaCu2Sn2 (new structure type), C2/m, a = 10.943(3) Å, b = 4.222(1) Å, c = 4.834(1) Å, β = 107.94(1)°, Z = 2, wR2 = 0.051, 343 F2 values; CaCu9Sn4 (LaFe9Si4 type), I4/mcm, a = 8.630(1) Å, c = 12.402(1) Å, Z = 4, wR2 = 0.047, 566 F2 values. In all phases the shortest Cu‐Sn distances are in the range 2.59‐2.66Å, while the shortest Cu‐Cu distances are practically the same, 2.53‐2.54Å, except CaCuSn where no Cu‐Cu contacts occur.
Synthese von Y2O2(CN2) und Leuchtstoffeigenschaften von Y2O2(CN2):Eu
Authors: Sindlinger Jörg , Glaser Jochen , Bettentrup Helga , Jüstel Thomas , Meyer H.‐Jürgen 
Published: July 2007

AbstractSynthesis of Y2O2(CN2) and Luminescence Properties of Y2O2(CN2):EuCrystalline powders of the new compound Y2O2(CN2) were prepared by solid state reactions from different mixtures of YCl3/YOCl/Y2O3 and Li2(CN2) at temperatures between 620 °C and 650 °C. Structure refinements based on X‐ray powder diffraction revealed that trigonal Y2O2(CN2) crystallizes with a structure that is closely related to that of Y2O2S, whereas linear N‐C‐N units replace sulphur atoms in Y2O2S. In addition, a hexagonal polytype of Y2O2(CN2) was obtained in which a different stacking sequence of yttrium atoms creates a doubling of the c‐axis. Europium‐doped samples of Y2O2(CN2) were prepared and the luminescence properties of Y2O2(CN2):Eu are presented.
Synthesis, Spectral, Thermal and Structural Characterization of mer‐Triaquaorotatoquinoxaline Cadmium(II) Dihydrate
Authors: Yeşilel Okan Zafer , Paşaoğlu Hümeyra , Akdağ Kamber , Büyükgüngör Orhan 
Published: July 2007

AbstractThe new orotate complex of cadmium(II) with quinoxaline, mer‐[Cd(HOr)(H2O)3(QX)]·2H2O, was synthesized and characterized by elemental analysis, FT–IR spectroscopy, thermal analysis and single crystal X–ray diffraction techniques. The complex crystallizes in the triclinic system, space group $P{\bar 1}$. The Cd2+ ion exhibits a distorted octahedral coordination by one bidentate orotate, one monodentate quinoxaline and three aqua ligands. The uncoordinated water molecules link the orotate, quinoxaline and aqua ligands via O–H···O, O–H···N hydrogen bonds. Thus, an extensive network of hydrogen bonds stabilizes the crystal structure and form an infinitive three dimensional lattice. The decomposition reaction takes place in the temperature range 20–700 °C in the static air atmosphere.
Synthese und Kristallstrukturen des Zink‐Rhodiumborids Zn5Rh8B4 und der Lithium‐ Magnesium‐Rhodiumboride LixMg5−xRh8B4 (x = 1.1 und 0.5) und Li8Mg4Rh19B12
Authors: Hartung Hans , Schiffer Joachim , Nagelschmitz Ernst A. , Jung Walter 
Published: July 2007

AbstractSynthesis and Crystal Structures of Zinc Rhodium Boride Zn5Rh8B4 and the Lithium Magnesium Rhodium Borides LixMg5−xRh8B4 (x = 1.1 and 0.5) and Li8Mg4Rh19B12The title compounds were prepared by reaction of the elemental components in metal ampoules under argon atmosphere (1100 °C, 7 d). In the case of Zn5Rh8B4 (orthorhombic, space group Cmmm, a = 8.467(2) Å, b = 16.787(3) Å, c = 2.846(1) Å, Z = 2) a BN crucible enclosed in a sealed tantalum container was used. The syntheses of LixMg5−xRh8B4 (orthorhombic, space group Cmmm, Z = 2, isotypic with Zn5Rh8B4, lattice constants for x = 1.1: a = 8.511(3) Å, b = 16.588(6) Å, c = 2.885(1) Å, and for x = 0.5: a = 8.613(1) Å, b = 16.949(3) Å, c = 2.9139(2) Å) and Li8Mg4Rh19B12 (orthorhombic, space group Pbam, a = 26.210(5) Å, b = 13.612(4) Å, c = 2.8530(5) Å, Z = 2) were carried out in tantalum crucibles enclosed in steel containers using lithium as a metal flux. The crystal structures were solved from single crystal X‐ray diffraction data. In both structures Rh atoms reside at z = 0 and all non‐transition metal atoms at z = 1/2. Columns of Rh6B trigonal prisms running along the c‐axis are laterally connected to form three‐dimensional networks with channels of various cross sections containing Li‐, Mg‐, and Zn‐atoms, respectively. A very short Li‐Li distance of 2.29(7) Å is observed in Li8Mg4Rh19B12.
Synthese und Struktur von N,N,N‴,N‴‐Tetraisobutyl‐N′,N″‐isophthaloylbis(thioharnstoff) und Dimethanol‐bis(N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(thioureato))dicobalt(II)
Authors: Rodenstein Axel , Richter Rainer , Kirmse Reinhard 
Published: July 2007

AbstractSynthesis and Structure of N,N,N‴,N‴‐Tetraisobutyl‐N′,N″‐isophthaloylbis(thiourea) and Dimethanol‐bis(N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(thioureato))dicobalt(II)The synthesis and the crystal structure of the ligand N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(thiourea) and its CoII‐complex are reported. The ligand co‐ordinates quadridentately forming a di‐bischelate. The donor atoms O and S are arranged in cis‐position around the central CoII ions. In addition the co‐ordination geometry is determined by methanol molecules resulting in the co‐ordination number five. The complex crystallizes in the space group P1 (Z = 1) with two additional methanol molecules per formula unit. The free ligand crystallizes in the space group P1 (Z = 2) with one methanol molecule per formula unit. It shows the typical keto form of N‐acylthioureas with a protonated central N atom. The structures of both acylthiourea fragments come close to E,Z′‐configurations.
A Computational Study of [M(CF3)4]− (M = Cu, Ag, Au) and their Properties as Weakly Coordinating Anions
Authors: Preiss Ulrich , Krossing Ingo 
Published: July 2007

AbstractThe properties of the tetrakis(trifluoromethyl)‐coinage metallates(III) [M(CF3)4]− (M = Cu, Ag, Au) as Weakly Coordinating Anions (WCAs) have been investigated with quantum mechanical methods in order to quantitatively compare them to other, well‐known WCAs. Also, several new decomposition pathways have been studied. Overall the coinage metallates perform rather well and should be used more frequently in preparative chemistry.
Übergangsmetallionen in Iodostannaten: Die Kristallstrukturen von [Co(en)3]4[Sn3I12]I2 und $^{3}_{\infty}\rm [Co(en)_{4}SnI_{4}]$
Authors: Lode Christine , Krautscheid Harald 
Published: July 2007

AbstractTransition Metal Ions in Iodostannates: the Crystal Structures of [Co(en)3]4[Sn3I12]I2 and $^{3}_{\infty}\rm [Co(en)_{4}SnI_{4}]$Under solvothermal conditions SnI2 reacts with transition metal complex cations to form anionic iodostannates as well as neutral iodocomplexes with divalent tin. In the crystal lattice of [Co(en)3]4[Sn3I12]I2 (1, en = H2NCH2CH2NH2) isolated [Sn3I12]6− anions and additional non‐coordinating iodide ions are present. The charge is balanced by [Co(en)3]2+ cations. In contrast, in [Co(en)2SnI4] (2) [SnI4]2− chains are linked by Co(en)22+ groups to form a three dimensional network.[Co(en)3]4[Sn3I12]I2 (1): a = 2180.44(8), b = 1354.41(5), c = 2630.53(10) pm, V = 7768.5(5)·106 pm3, space group Pbca.[Co(en)2SnI4] (2): a = 1149.1(1), b = 1207.5(1), c = 1397.0(1) pm, α = 68.07(1), β = 68.26(1), γ = 85.83(1)°, V = 1665.2(7)·106 pm3, space group $P{\bar 1}$.
Das System Gd/Co/B: Darstellung und röntgenographische Charakterisierung von GdCo4B, Gd3Co11B4, GdCoB4 und GdCo12B6
Authors: Cordier Gerhard , Klemens Rita , Albert Barbara 
Published: July 2007

AbstractThe System Gd/Co/B: Preparation and Characterization by X‐ray Diffraction of GdCo4B, Gd3Co11B4, GdCoB4, and GdCo12B6The compounds GdCo4B, Gd3Co11B4, GdCoB4, and GdCo12B6 were characterized by X‐ray investigations of single crystals. GdCo4B (P 6/mmm, a = 505.9(1) pm, c = 690.1(1) pm) crystallizes with the CeCo4B structure type; Gd3Co11B4 (P 6/mmm, a = 508.7(1) pm, c = 982.9(9) pm) with the Ce3Co11B4 stucture type; GdCo12B6 ($R{\bar 3}m$, a = 949.5(1) pm, c = 747.4(1) pm) with the SrNi12B6 structure type and GdCoB4 (P bam, a = 591.3(9) pm, b = 1145.1(6) pm, c = 346.2(3) pm) with the YbCoB4 structure type.
Structural Chemistry of Borophosphates, Metalloborophosphates, and Related Compounds
Authors: Ewald Bastian , Huang Ya‐Xi , Kniep Rüdiger 
Published: July 2007

AbstractA concept for the classification of crystalline (metallo)borophosphates in terms of structural chemistry is proposed and the compounds known to date are classified in an overview. Similarities and differences with (alumo)silicates and Liebau's classification are discussed with respect to the observation that the different borate and phosphate complexes are not interconnected arbitrarily in borophosphates. By combination and extension of existing concepts for silicates and borates a hierarchical system based on oligomeric building units has been developed. The observed connection rules are rationalized and the strong influence of the composition on dimensionality and structural motifs of the formed anions is pointed out. Likewise the effect of OH groups is taken into account by grading anions according to the degree of protonation (ratio O:OH). A general distinction is made between tetrahedral and mixed coordinated borophosphates. Metalloborophosphates are treated separately as special cases of borophosphates. Finally, anion‐substituted compounds, border cases, and borate‐phosphates complete the overview.
Synthesis, Structures and Spectroscopic Properties of Platinum(II), Palladium(II) and Copper(I) Halide Complexes with Pyrimidine‐phosphine Ligand
Authors: Zhang Jun‐Feng , Gan Xin , Xu Quan‐Qing , Chen Jian‐Hua , Yuan Mei , Fu Wen‐Fu 
Published: July 2007

AbstractThe reactions of pyrimidine‐phosphine ligand N‐[(diphenylphosphino)methyl]‐2‐pyrimidinamine (L) with various metal salts of PtII, PdII and CuI provide three new halide metal complexes, Pt2Cl4(μ‐L)2·2CH2Cl2 (1), Pd2Cl4(μ‐L)2 (2), and [Cu2(μ‐I)2L2]n (3). Single crystal X‐ray diffraction studies show that complexes 1 and 2 display a similar bimetallic twelve‐membered ring structure, while complex 3 consists of one‐dimensional polymeric chains, which are further connected into a 2‐D supramolecular framework through hydrogen bonds. In the binuclear complexes 1 and 2, the ligand L serves as a bridge with the N and P as coordination atoms, but in the polymeric complex 3, both bridging and chelating modes are adopted by the ligand. The spectroscopic properties of complexes 1‐3 as well as L have been investigated, in which complex 3 exhibits intense photoluminescence originating from intraligand charge transfer (ILCT) π→π* and metal‐to‐ligand charge‐transfer (MLCT) excited states both in acetonitrile solution and solid state, respectively.
Alkene‐ and Alkyne‐substituted Methylimidazolium Bromides: Structural Effects and Physical Properties
Authors: Schneider Stefan , Drake Gregory , Hall Leslie , Hawkins Tommy , Rosander Michael 
Published: July 2007

AbstractSeveral bromide salts composed of methylimidazolium cations possessing unsaturated sidechains (allyl‐, 3‐butenyl‐, propargyl‐, 2‐butynyl‐, and 2‐pentynyl‐) have been synthesized and characterized by multinuclear NMR, vibrational spectroscopy, DSC, and elemental analysis. Crystal structures of 1‐(2‐butynyl)‐3‐methylimidazolium bromide, 1‐propargyl‐3‐methylimidazolium bromide and 1‐allyl‐3‐methylimidazolium bromide, were determined.
From an Impurity to the Pure Compound – an Electron Microscopy Study
Authors: Kienle Lorenz , Lukachuk M. , Duppel V. , Mattausch Hj. , Simon A. 
Published: July 2007

AbstractThe power of electron microscopy techniques for the determination of structure and composition of marginal byproducts is demonstrated for rare earth metal cluster compounds. Small amounts of the new phase Gd4GaI6 in samples with the nominal composition Gd7GaI12 could only be identified by a combined approach of EDX, electron diffraction and HRTEM. The structure of Gd4GaI6 can be assigned to the Y4BBr6‐type containing chains of Gd6 octahedra which are centered by Ga atoms. The results of the electron microscopy study initiated the synthesis of homogeneous samples of the new compound Gd4GaI6 by applying the correct ratio of the starting materials.
Synthesis, Structure, and High Temperature Thermoelectric Properties of Yb11Sb9.3Ge0.5
Authors: Rauscher Japheth F. , Kauzlarich Susan M. , Ikeda Teruyuki , Snyder G. Jeffrey 
Published: July 2007

AbstractZintl phase compounds with large unit cells and complex anionic structures such as Yb11Sb10 hold potential for being good thermoelectric materials. Single crystals of Ge‐doped Yb11Sb10 were synthesized using a molten Sn‐flux technique. Single crystal X‐ray diffraction data were obtained and resulted in a composition of Yb11Sb9.3Ge0.5 which was verified by microprobe. Yb11Sb9.3Ge0.5 is isostructural to Ho11Ge10, crystallizing in a body‐centered, tetragonal unit cell, space group I4/mmm, with Z = 4. The unit cell parameters of Yb11Sb9.3Ge0.5 are a = 11.8813(4), c = 17.1276(13) Å with a volume of 2417.8(2) Å3. These parameters correlate well with the structural refinement of previously published Yb11Sb10. The structure consists of 16 isolated Sb3− anions, 8 $\rm Sb^{4-}_{2}$ dumbbells, 2 $\rm Sb^{4-}_{4}$ square planar rings and 44 Yb2+ cations. The Ge, doped in at 28 % occupancy, was found to be site specific, residing on the 2 $\rm Sb^{4-}_{4}$ square planar rings. Single crystal X‐ray diffraction is most consistent with the site that makes up the square ring being less than fully occupied. The doped compound is additionally characterized by X‐ray powder diffraction, differential scanning calorimetry and thermogravimetry. High temperature (300–1200 K) thermoelectric properties show that the doped compound has extremely low thermal conductivity (10–30 mW/cmK), lower than that of Yb11Sb10. Temperature dependent resistivity is consistent with a heavily doped semiconductor. Yb11Sb9.3Ge0.5 shows p‐type behavior increasing from ∼22 μV/K at room temperature to ∼31 μV/K at 1140 K. The low value and the temperature dependence of the Seebeck coefficient suggest that bipolar conduction produces a compensated Seebeck coefficient and consequently a low zT.
A S8‐like [Sb8]8− Zintl Anion in the Ammoniate [K17(Sb8)2(NH2)] · 17.5NH3
Authors: Reil Markus , Korber Nikolaus 
Published: July 2007

AbstractThe ammoniate [K17(Sb8)2(NH2)] · 17.5NH3 was synthesized by reduction of antimony with potassium in liquid ammonia. Single crystals were isolated and characterized by low temperature X‐ray structure analysis. [K17(Sb8)2(NH2)] · 17.5NH3 crystallizes in the space group P21/c (No. 14) with a = 12.976(1) Å, b = 24.536(1) Å, c = 22.858(1) Å and β = 99.17(1)°. The ammoniate contains crown‐shaped [Sb8]8− Zintl anions which are analogous to S8 rings. The presence of amide NH2− as an additional anion is deduced from coordination observations and the close similarity of structural features to the structure of KNH2.
Melengestrol acetate implant contraception in addax (Addax Nasomaculatus) and Arabian oryx (Oryx Leucoryx)
Authors: Hall‐Woods Monica L. , Bauman Karen L. , Bauman Joan E. , Fischer Martha , Houston E. William , Asa Cheryl S. 
Published: July 2007

AbstractMelengestrol acetate (MGA) implants were used for contraception in three addax and three Arabian oryx females housed at the Saint Louis Zoo. Serum estradiol and progesterone or fecal estrogen and progestin analysis and ultrasonography of reproductive tracts were used for monitoring changes before, during, and after MGA treatment. Follicular development and irregular uterine fluid accumulation were detected in all females during MGA treatment. Although housed with an intact male for all or most of the contraceptive period, no pregnancies occurred.One female addax may have ovulated, based on sustained elevated progesterone levels, and another showed continued follicle development, as seen by fluctuating estradiol concentrations. Reversibility was documented in two of the three addax that resumed reproductive cycles post‐MGA‐implant removal, whereas the third, a peripubertal female, did not cycle before, during, or after treatment. Addax females were lost to further follow‐up after transfer to another institution, so the possibility of subsequent pregnancies is not known.All three Arabian oryx ovulated during the initial MGA treatment, but two of the three females had implants past the typical 2‐year efficacy period. They had regular ovulatory cycles after implant removal, with mean cycle length of 27.5±1.5 days and mean luteal phase duration of 15.2±0.7 days. Reversibility was further shown in all three oryx by pregnancies after placement with a male approximately 2 years after MGA implant removal. Two produced healthy calves, but the third died owing to an unrelated terminal illness in the mother. Zoo Biol 26:299–310, 2007. © 2007 Wiley‐Liss, Inc.
The effects of rearing method on social behaviors of mentored, captive‐reared juvenile California condors
Authors: Utt Amy C. , Harvey Nancy C. , Hayes William K. , Carter Ronald L. 
Published: July 2007

AbstractPuppet‐reared and parent‐reared captive‐bred California condor (Gymnogyps californianus) juveniles were studied before their release into the wild. Behavioral data were collected during social interactions within two cohorts of juveniles (N = 11) and their adult mentors (N = 5). The purposes of this study were to (1) document the social behaviors of mentored juvenile California condors, and (2) compare social behaviors for two different rearing methods (puppet‐reared versus parent‐reared) during two phases of the mentoring process (San Diego Wild Animal Park versus release sites). Of the 17 behaviors examined by 2 × 2 analyses of variance (ANOVAs), two significant interactions between the rearing method and mentoring phase were found: pulls feathers and feeds alone. For both behaviors, parent‐reared condors engaged in these activities more often at the zoo and less often at the release pens than did the puppet‐reared condors. The main effect of rearing was also significant for two behaviors: near others, and receives contact aggression from other. Parent‐reared birds were more likely to be near another bird and receive contact aggression, regardless of mentoring phase, than puppet‐reared birds. The effect size for 16 of the 17 behaviors was greater for the rearing method than for mentoring phase. Rearing method differences may persist long‐term, as parent‐reared adult mentors were significantly more aggressive than puppet‐reared adult mentors. Dominance relations were examined for both cohorts, with the first cohort exhibiting a strong linear relationship (h′ = 0.86, P = 0.018), whereas the second cohort exhibited a moderate but non‐significant linear hierarchy (h′ = 0.63, P = 0.21). The rearing method had no effect on dominance among the juveniles, but adults were probably dominant to juveniles (P = 0.052; the difference was nearly significant). Although social behaviors between the two rearing groups were similar in most respects, this study is the first to document measurable differences between puppet‐ and parent‐reared captive‐bred California condor juveniles. Zoo Biol 27:1–18, 2008. © 2007 Wiley‐Liss, Inc.
Increased Risk of Lymph Node Metastasis in Multifocal Hereditary and Sporadic Medullary Thyroid Cancer
Authors: Machens Andreas , Hauptmann Steffen , Dralle Henning 
Published: July 2007

AbstractBackgroundIn sporadic and hereditary medullary thyroid cancer, tumor multifocality may constitute an independent risk factor of lymph node metastasis on top of primary tumor size when the diameter of the largest primary tumor is the same.MethodsIncluded in this institutional cohort study were 232 consecutive patients operated on at our institution for hitherto untreated medullary thyroid cancer. Associations of clinicopathologic variables with lymph node metastasis were investigated simultaneously using multivariate Cox regression analysis.ResultsOn univariate analysis, multifocal cancers developed lymph node metastases significantly more often (p≤ 0.005) than unifocal cancers, in both the sporadic (90% vs. 41%) and the hereditary setting (48% vs. 14%). On multivariate Cox regression analysis on lymph node metastasis as a function of primary tumor diameter, only multifocal (vs. unifocal) tumor growth was significantly associated with lymph node metastasis (odds ratio [OR] = 2.5;p= 0.01). When multifocal growth was removed as an independent variable from the Cox model, heredity became the only significant predictor (OR = 3.1;p< 0.0001).ConclusionThe excess risk of lymph node metastasis of 34%‐49% in multifocal medullary thyroid cancer seems to be caused by concurrent smaller thyroid cancers. A diagnosis of more than one medullary thyroid cancer signifies a higher risk of lymph node metastasis, warranting systematic lymph node dissection.