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Self‐assembly FeII complexes of phenazine (Phen), quinoxaline (Qxn), and 4,4′‐trimethylenedipyridine (Tmp) with tetrahedral building blocks of [HgII(XCN)4]2− (X=S or Se) formed six new high‐dimensional frameworks with the general formula of [Fe(L)m][Hg(XCN)4]⋅solvents (L=Phen, m/X=2/S, 1; L=Qxn, m/X=2/S, 2; L=Qxn, m/X=1/S, 3; L=Qxn, m/X=1/Se, 3‐Se; L=Tmp, m/X=1/S, 4; and L=Tmp, m/X=1/Se, 4‐Se). 1, 3, and 3‐Se show an intense sub‐terahertz (sub‐THz) absorbance of around 0.60 THz due to vibrations of the solvent molecules coordinated to the FeII ions and crystallization organic molecules. In addition, crystals of 1, 4, and 4‐Se display low‐frequency Raman scattering with exceptionally low values of 0.44, 0.51, and 0.53 THz, respectively. These results indicate that heavy metal FeII−HgII systems are promising platforms to construct sub‐THz absorbers. [ABSTRACT FROM AUTHOR]

Gold complexes can generate excimers ([Au2]→[Au2]*) and exciplexes ([Au3]→[Au3]*) with light excitation. Four GdIII and YIII complexes were assembled with dimeric {[Au(SCN)2]−}2 and trimeric {[Au(SCN)2]−}3 bis(thiocyanato)gold(I) counterions. The vibrational signature associated with the Au⋅⋅⋅Au vibrational mode was probed with ultralow frequency (ULF) Raman spectroscopy as a function of temperature. Emission spectroscopy was used to explore photophysical properties. Two broad features in the high‐ and low‐energy regions were associated with the fluorescence and phosphorescence of the gold entities, respectively. Temperature‐dependent luminescence measurements showed that the emission color can be tuned from blue to green via cyan and white. Hence, these complexes can act as colorimetric thermometers. Additionally, a ratiometric thermal sensing ability was incorporated with high sensitivity up to 5 % K−1 in the cryogenic temperature range. [ABSTRACT FROM AUTHOR]

The development of multifunctional oriented polar crystals combining diverse optical, nonlinear optical, and magnetic phenomena are desirable. Two enantiomorphic assemblies [YbIII(TPPO)3(NCE)3] (E = S ("YbS"), Se ("YbSe"); TPPO = triphenylphosphine oxide) are prepared. Both crystallites show ultralow‐frequency (ULF) Raman scattering for molecular materials with a value of 16 cm−1 (0.48 THz), originating from collective vibrations of the TPPO ligand and pseudohalides, which is supported by ab initio calculations. Moreover, YbS and YbSe crystals exhibit high‐intense second harmonic generation (SHG) phenomena along the threefold rotation c‐axis. The polarization‐variation of the pumping laser electric field experiment performed on single crystals gives a unique insight into the tensor elements constituting the R3 space group. Replacement of thiocyanide with selenocyanide in YbSe compound increases the second harmonic signal attributed to increased polarization. Besides, they also exhibit 4f‐metal centered high‐performance near‐infrared luminescence thermometric properties and weak single‐molecule magnet behaviors. They can also serve as a platform to study the magnetic and linear/nonlinear optical cross effects. [ABSTRACT FROM AUTHOR]

Keywords: charge transfer; cobalt; heterometallic complexes; magnetic properties; spin crossover EN charge transfer cobalt heterometallic complexes magnetic properties spin crossover 1 1 1 10/20/23 20231024 NES 231024 B The Front Cover b shows the structural unit of the newly discovered [Co(terpy) SB 2 sb ] SB 3 sb [W(CN) SB 8 sb ] SB 2 sb B - b 12H SB 2 sb O compound, terpy=2,2':6',2"-terpyridine. Front Cover: Water-Solvation-Dependent Spin Transitions in Cobalt(II)-Octacyanidometallate Complexes (Eur. J. Inorg. Charge transfer, cobalt, heterometallic complexes, magnetic properties, spin crossover. [Extracted from the article]

The microwave-mediated self-assembly of [WV(CN)8]3- with CuII in the presence of pyrazole ligand resulted in the formation of three novel assemblies: CuII2(Hpyr)5(H2O)[WV(CN)8](NO3)∙H2O (1), {CuII5(Hpyr)18[WV(CN)8]4}∙[CuII(Hpyr)4(H2O)2]∙9H2O (2), and CuII4(Hpyr)10(H2O)[WV(CN)8]2(HCOO)2∙4.5H2O (3) (Hpyr =1H-pyrazole). Single-crystal X-ray structure of 1 consists of cyanido-bridged 1-D chains of vertex-sharing squares topology. The structure of 2 reveals 2-D hybrid inorganic layer topology with large coordination spaces occupied by {Cu(Hpyr)2(H2O)4}2+ ions. Compound 3 contains two types of cyanido-bridged 1-D chains of vertex-sharing squares linked together by formate ions in two directions forming hybrid inorganic—organic 3-D framework (I1O2). The magnetic measurements for 1—3 reveal a weak ferromagnetic coupling through CuII—NC—WV bridges. [ABSTRACT FROM AUTHOR]

Optically active functional noncentrosymmetric architectures might be achieved through the combination of molecules with inscribed optical responses and species of dedicated tectonic character. Herein, we present the new series of noncentrosymmetric cocrystal salt solvates (PPh 4 ) 3 [M(CN) 6 ](L) n · m solv (M = Cr(III), Fe(III), Co(III); L = polyresorcinol coformers, multiple hydrogen bond donors: 3,3',5,5'-tetrahydroxy-1,19-biphenyl, DiR, n = 2, or 5'-(3,5-dihydroxyphenyl)-3,3″,5,5″-tetrahydroxy-1,19:3',1″-terphenyl, TriRB, n = 1) denoted as MDiR and MTriRB , respectively. The hydrogen-bonded subnetworks {[M(CN) 6 ] 3- ;L n } ∞ of dmp , neb , or dia topology are formed through structural matching between building blocks within supramolecular cis -bis(chelate)-like {[M(CN) 6 ] 3- ;( H 2 L) 2 ( H L) 2 } or tris(chelate)-like {[M(CN) 6 ] 3- ;( H 2 L) 3 } fragments. The quantum-chemical analysis demonstrates the mixed electrostatic and covalent character of these interactions, with their strength clearly enhanced due to the negative charge of the hydrogen bond acceptor metal complex. The corresponding interaction energy is also dependent on the geometry of the contact and size matching of its components, rotational degree of freedom and extent of the π-electron system of the coformer, and overall fit to the molecular surroundings. Symmetry of the crystal lattices is correlated with the local symmetry of coformers and {complex;(coformer) n } hydrogen-bonded motifs characterized by the absence of the inversion center and mirror plane. All compounds reveal second-harmonic generation activity and photoluminescence diversified by individual UV-vis spectral characteristics of the components, and interesting low-frequency Raman scattering spectra within the subterahertz spectroscopic domain. Vibrational (infrared/Raman), UV-vis electronic absorption (experimental and calculated), and 57 Fe Mössbauer spectra together with electrospray ionization mass spectrometry (ESI-MS) data are provided for the complete description of our systems.

Research on isomers is highly desirable due to their prospective role in better understanding of physicochemical properties of similar systems and further development of multifunctional molecular materials. Iron(II) and tetra(thiocyanato)mercury(II) ions self-assembled in the presence of 2-acetylpyridine (2-acpy) excess to form two {[Fe(2-acpy)][Hg(μ-SCN) 4 ]} n isomers: two-dimensional (2D) centrosymmetric layers with folded ring structural motifs ( 1 ) and three-dimensional (3D) chiral networks with right- or left-handed {···Fe-NCS-Hg-SCN···} ∞ helixes ( 2 ). New methods of designing and synthesizing functional thiocyanate-bridged materials have been proposed. In addition, the similarity between 1 and 2 allowed for the description of subtle changes in IR and UV-visible spectra. Moreover, 2 shows spontaneous resolution, and it crystallizes in the noncentrosymmetric space group P 2 1 , leading to the occurrence of nonlinear optical activity in circular dichroism studies and second harmonic generation (SHG). At room temperature, the SH susceptibility for powder sample 2 reached 6.0 × 10 -11 esu. Ab initio calculations indicated the electric polarization vector and the crystallographic twofold screw axis pass through the aromatic ring. Magnetic studies for 1 and 2 revealed high-spin iron(II) with zero-field splitting at low temperatures. Analysis of magnetic data gave | D| = 37.45 cm -1 , | E / D | = 5.59 cm -1 , and ⟨ g ⟩ = 2.15 for 1 , | D| = 36.78 cm - 1 , | E / D | = 4.92 cm -1 , and ⟨ g ⟩ = 2.18 for 2 , and information about the orientation of magnetic anisotropy vectors for both compounds.

Self-assembly Fe II complexes of phenazine (Phen), quinoxaline (Qxn), and 4,4'-trimethylenedipyridine (Tmp) with tetrahedral building blocks of [Hg II (XCN) 4 ] 2- (X=S or Se) formed six new high-dimensional frameworks with the general formula of [Fe(L) m ][Hg(XCN) 4 ]⋅solvents (L=Phen, m/X=2/S, 1; L=Qxn, m/X=2/S, 2; L=Qxn, m/X=1/S, 3; L=Qxn, m/X=1/Se, 3-Se; L=Tmp, m/X=1/S, 4; and L=Tmp, m/X=1/Se, 4-Se). 1, 3, and 3-Se show an intense sub-terahertz (sub-THz) absorbance of around 0.60 THz due to vibrations of the solvent molecules coordinated to the Fe II ions and crystallization organic molecules. In addition, crystals of 1, 4, and 4-Se display low-frequency Raman scattering with exceptionally low values of 0.44, 0.51, and 0.53 THz, respectively. These results indicate that heavy metal Fe II -Hg II systems are promising platforms to construct sub-THz absorbers., (© 2022 Wiley-VCH GmbH.)

Gold complexes can generate excimers ([Au 2 ]→[Au 2 ]*) and exciplexes ([Au 3 ]→[Au 3 ]*) with light excitation. Four Gd III and Y III complexes were assembled with dimeric {[Au(SCN) 2 ] - } 2 and trimeric {[Au(SCN) 2 ] - } 3 bis(thiocyanato)gold(I) counterions. The vibrational signature associated with the Au⋅⋅⋅Au vibrational mode was probed with ultralow frequency (ULF) Raman spectroscopy as a function of temperature. Emission spectroscopy was used to explore photophysical properties. Two broad features in the high- and low-energy regions were associated with the fluorescence and phosphorescence of the gold entities, respectively. Temperature-dependent luminescence measurements showed that the emission color can be tuned from blue to green via cyan and white. Hence, these complexes can act as colorimetric thermometers. Additionally, a ratiometric thermal sensing ability was incorporated with high sensitivity up to 5 % K -1 in the cryogenic temperature range., (© 2022 Wiley-VCH GmbH.)

Spin-transition compounds are coordination complexes that can present two stable or metastable high-spin and low-spin states at a given temperature (thermal hysteresis). The width of the thermal hysteresis (difference between the maximum and minimum temperature between which the compound exhibits bi-stability) depends on the interactions between the coordination complexes within the compound, and which may be modulated by the absence or presence of solvent within the structure. The new compound [Fe(3-bpp) 2 ][Au(CN) 2 ] 2 (1, 3-bpp=2,6-di-(1H-pyrazol-3-yl)pyridine) was synthesized and its properties were compared with those of the solvated compound [Fe(3-bpp) 2 ][Au(CN) 2 ] 2 ⋅2 H 2 O (1.H 2 O) already described. 1 has a two-steps thermal hysteresis of 45 K, in contrast to the compound 1.H 2 O which exhibits a gradual conversion without hysteresis. This hysteretic transition is accompanied by a reversible reconstructive structural transition and twinning. This stepped behaviour is also observed in the photomagnetic properties despite the low efficiency of photoswitching. Single-crystal photocrystallographic investigations confirm this low conversion, which we attributed to the high energy cost to form the high-spin structure, whose symmetry differs from that of the low-spin phase., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)