In the reaction of 1,3-dimethyl-pyrazole-5-carboxylic acid (HL) with
M(OAc)2?4H2O, (M = Cu, Co) two novel complexes have been prepared,
square-planar CuL2(H2O)2 and octahedral CoL2(MeOH)4. The ...crystal
structures have been determined by single-crystal X-ray diffraction. In both
complexes the deprotonated acid displays monodentate coordination to the
metal ions. According to the results of CSD survey this is the first
structural report on the metal complexes with N1-substituted
pyrazole-5-carboxylic ligand.
Two novel nitrogen‐rich lanthanide compounds of 5,5'‐(azo bis)tetrazolide (ZT) were synthesized and structurally characterized. The dinuclear, isostructural compounds Ce2(ZT)2CO3(H2O)12 · 4 H2O (1) ...and Pr2(ZT)2CO3(H2O)12·4H2O (2) were synthesized via two independent routes. Compound 1 was obtained after partial Lewis acidic decomposition of ZT by CeIV in aqueous solution of (NH4)2Ce(NO3)6 and Na2ZT. Compound 2 was obtained by crystallization from aqueous solutions of Pr(NO3)3, Na2ZT, and Na2CO3. By X‐ray diffraction analysis at 200 K, it was found that the trivalent lanthanide cations are bridged by a bidentate carbonato ligand and each cation is further coordinated by six H2O ligands and one ZT ligand thus being ninefold coordinated.
The cover picture shows the molecular structure of a new type of binuclear early rare earth element complex that involves a bridging carbonato ligand, as well as 5,5'‐(azobis)tetrazolide (ZT) and ...aquo ligands. The compound is like a satellite sailing at the border between the Lewis acidic cation and the acid‐sensitive carbonate, with the ZTs as its solar panels. It illustrates the delicate synthesis in a subtle interplay between Lewis acidity of the CeIV precursor and the chemical stabilities of carbonate and ZT. More details can be found in the Article by Peter Weinberger, Gerald Giester, and Georg Steinhauser on page 1882 ff.
The two new copper(II) salts Cu(SeO
4
) and Cu(SeO
3
OH)
2
·6H
2
O were synthesized at low-temperature hydrothermal conditions (220 °C), and room temperature, respectively. Their atomic arrangements ...were studied based on single-crystal X-ray investigations
P
2
1
/
n, a
= 4.823(1),
b
= 8.957(2),
c
= 6.953(1) Å, β = 94.82(1)°, Z = 4;
P
1
¯
,
a
= 6.133(1),
b
= 6.303(1),
c
= 8.648(2) Å, α = 70.45(1), β = 84.60(1), γ = 73.44(1)°, Z = 1. Cu(SeO
4
) adopts the MnAsO
4
structure type. It exhibits structural as well as topological relations with two formerly known isochemical compounds. They crystallize in the structure type ZnSO
4
(mineral name zincosite,
Pnma
) respectively NiSO
4
(
Cmcm
). The two minerals dravertite, CuMg(SO
4
)
2
, and hermannjahnite, CuZn(SO
4
)
2
, are isotypic with CuSeO
4
-
P
2
1
/
n;
interestingly, also α-NaCu(PO
4
) belongs to this structure type: some rotation of the
X
O
4
group allows a supplementary position for the Na atom. — Cu(SeO
3
OH)
2
·6H
2
O represents a new structure type. The protonated selenate group shows an extended Se—O
h
bond distance (1.695 Å) as compared to the other Se—O bonds (1.614 to 1.626 Å). One OH dipole of the three independent H
2
O molecules represents a rather free hydrogen bond. For the other H atoms, the O—H···O lengths vary from 2.585 to 2.799 Å. Interestingly, the distance O
w
7···O
w
7 of only 2.791 Å does not represent an edge in a coordination polyhedron and it is not preliminary involved in the hydrogen bond scheme. All Cu
2+
ions in the two title compounds are in a pronounced 4 + 2 coordination. The Cu
2+4+2
atoms in Cu(SeO
4
) are linked to chains along 100; in Cu(SeO
3
OH)
2
·6H
2
O they are not connected among each other.
Investigation (electron microprobe and X-ray powder and single crystal diffraction analyses) of the phase relations in the Mn-rich corner (> 45 at% Mn) of the systems Mn-{Ru,Os,Ir}-B, prompted in all ...three systems a ternary compound with formula (Mnx{Ru,Os,Ir}1-x)23B6. For the systems Mn-Ru-B, Mn-Ir-B phase equilibria have been determined at 950°C (Ru), 900°C (Ir) revealing in both cases a small homogeneity region at constant B-content (Mn1-xRux)23B6 (0.29 < x < 0.37); (Mn1-xOsx)23B6 (0.33 < x < 0.37), as well as (Mn1-xIrx)23B6 (0.29 < x < 0.34). The crystal structure of the three compounds was determined from single crystal and X-ray powder intensity data analyses to be isotypic with the Cr23B6-type (so-called tau-phase, space group Fm3¯m, No. 225). In all cases Mn atoms fully occupy the 4a site (0,0,0) at the origin of the unit cell. For the 8c site (¼,¼,¼) we observed a random distribution of Mn1-x(PM)x with decreasing PM content (PM stands for a platinum group metal atom) going from Ru to Os and Ir, where Mn atoms fully occupy 8c. Whereas the remaining sites (48h, 32f) show various ratios of the two metal species, boron atoms fully occupy the centers (24e site) of the Archimedean metal atom antiprisms. A transmission electron microscopic study confirms the absence of superstructures related to these metal atom disorder, thus Mn and PM atoms randomly share their sites. The latter is well reflected in the behavior of the electrical resistivity of these compounds, which is dominated by disorder scattering. For (Mn0.6{Ru,Os}0.4)23B6, temperature dependent dc magnetization studies reveal distinct antiferromagnetic-like anomalies at TN ≅ 72 K and 114 K, respectively. Low field dc and ac magnetic susceptibility data of (Mn0.7Ir0.3)23B6 display a distinct ferromagnetic-like transition at TC = 280 K, consistent with a pronounced specific heat anomaly and a rather continuous temperature dependent evolution of magnetic anisotropy effects. Mechanical properties (hardness) characterize the tau phases among rather hard and brittle intermetallics (about 5–6 GPa).
•Phase relations at ∼900°C in the Mn-corner of the systems Mn-{Ru,Ir}-B.•Single crystal structure analyses (Xray, TEM) of novel Mnx{Ru,Os,Ir}23-xB6.•Tau-borides: Experimental Cp, ρ, χ, ac/dc-magnetization, elastic moduli, HV.•Antiferromagnetic-like anomalies for (Mn0.6{Ru,Os}0.4)23B6 at TN ≅ 72 K, 114 K.•Ferromagnetic-like transition for (Mn0.7Ir0.3)23B6 at TC = 280 K.
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