Cluster‐Based Cu<sup>II</sup>–Azide Polymers: Synthesis, Structure, Magnetic Properties, and Effect of Polyamines on Crystal Structures

Tian, Chong‐Bin; Li, Zhihua; Lin, Jian-Di; Wu, Shuting; Du, Shaowu; Lin, Ping

doi:10.1002/ejic.200900776

Cited by 59 publications

(6 citation statements)

References 57 publications

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“…[1][2][3][4] The ability of azide to coordinate to two metal centers with multiple coordination modes finds a broad application in the field of molecular magnetism. [5][6][7][8][9] If two paramagnetic metal ions are connected via azide ligands in a bridging end-on (m-h 1 :h 1 ) coordination, the resulting metal-metal exchange interaction is generally found to be ferromagnetic, 8,9 thus allowing for the synthesis of complexes with a wide range of magnetic behavior.…”

Section: Introductionmentioning

confidence: 99%

Ground and excited state properties of photoactive platinum(iv) diazido complexes: Theoretical considerations

Sokolov

Schaefer

2011

Dalton Trans.

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Recently synthesized by the group of Sadler, the platinum(IV) diazido complexes [Pt(N(3))(2)(OH)(2)(L')(L'')] (L' and L'' are N-donor ligands) have potential to be used as photoactivatable metallodrugs in cancer chemotherapy. In the present study optimized structures and UV-Vis electronic spectra of trans,trans,trans- and cis,trans,cis-[Pt(N(3))(2)(OH)(2)(NH(3))(2)] (1t and 1c, respectively) as well as cis,trans,cis-[Pt(N(3))(2)(OH)(2)(L)(2)] (L = NH(3), NH(2)CH(3), NF(3), PH(3), PF(3), H(2)O, CO, OH(-), CN(-), py, imid; 2c-11c) and cis,trans-[Pt(N(3))(2)(OH)(2)(bpy)] (12c) complexes were predicted using density functional theory (DFT). The ground state electronic structures of all complexes were analyzed with the help of the natural bond orbital analysis (NBO). The electronic spectra of 1c and 1t were computed using time-dependent density functional theory (TDDFT) with five different density functionals and the ab initio CASSCF/CASPT2 method (for the five lowest energy transitions). The best agreement with available experiments was found in the case of the long-range corrected ωB97X functional. The electronic transitions were characterized by the analysis of the natural transition orbitals (NTO). The low-lying excited singlet states of 1t and 1c have significant azide-to-platinum(IV) charge-transfer character (LMCT). Geometry optimization of the three lowest singlet excited states performed using TDDFT results in the simultaneous dissociation of two azide ligands with the formation of the azidyl radicals N(3)˙ and photoreduction of Pt(IV) to Pt(II). Variation of the ligand L does not strongly affect the nature and the relative energies of the low-lying states. It is shown that the replacement of the OH(-) groups in 1c by OPh(-) ligands results in the red shift of the intense N(3)(-)→Pt LMCT band and the appearance of transitions with significant intensity in the visible region of the spectrum. The dissociative nature of the low-lying unoccupied orbitals remains unaffected. These theoretical results may suggest new experimental routes for the improvement of the photochemical activity of Pt(IV) diazido complexes.

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Section: Introductionmentioning

confidence: 99%

Ground and excited state properties of photoactive platinum(iv) diazido complexes: Theoretical considerations

Sokolov

Schaefer

2011

Dalton Trans.

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“…In [Cu(AA)(trien)](ClO 4 ) 2 (AA = bpy, phen) moieties, high conformational flexibility of trien resulted in octahedral coordination with significant elongation of one outer Cu-N trien (2.670 and 2.723 Å for phen and bpy, respectively) bond due to the Jahn–Teller effect [ 88 ]. Similar Cu-N trien bonds (1.996–2.019 Å) were noted for a homonuclear coordination polymer with azide bridges [ 89 ]. The selected valence angle description is given in the Supplementary Materials .…”

Section: Resultsmentioning

confidence: 59%

Structural Diversity, XAS and Magnetism of Copper(II)-Nickel(II) Heterometallic Complexes Based on the [Ni(NCS)6]4− Unit

et al. 2023

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The new heterometallic compounds, [{Cu(pn)2}2Ni(NCS)6]n·2nH2O (1), [{CuII(trien)}2Ni(NCS)6CuI(NCS)]n (2) and [Cu(tren)(NCS)]4[Ni(NCS)6] (3) (pn = 1,2-diaminopropane, trien = triethylenetetramine and tren = tris(2-aminoethylo)amine), were obtained and characterized by X-ray analysis, IR spectra, XAS and magnetic measurements. Compounds 1, 2 and 3 show the structural diversity of 2D, 1D and 0D compounds, respectively. Depending on the polyamine used, different coordination polyhedron for Cu(II) was found, i.e., distorted octahedral (1), square pyramidal (2) and trigonal bipyramidal (3), whereas coordination polyhedron for nickel(II) was always octahedral. It provides an approach for tailoring magnetic properties by proper selection of auxiliary ligands determining the topology. In 1, thiocyanate ligands form bridges between the copper and nickel ions, creating 2D layers of sql topology with weak ferromagnetic interactions. Compound 2 is a mixed-valence copper coordination polymer and shows the rare ladder topology of 1D chains decorated with [CuII(tren)]2+ antennas as the side chains attached to nickel(II). The ladder rails are formed by alternately arranged Ni(II) and Cu(I) ions connected by N2 thiocyanate anions and rungs made by N3 thiocyanate. For the Cu(I) ions, the tetrahedral thiocyanate environment mixed N/S donor atoms was found, confirming significant coordination spheres rearrangement occurring at the copper precursor together with the reduction in some Cu(II) to Cu(I). Such topology enables significant simplification of the magnetic properties modeling by assuming magnetic coupling inside {NiIICuII2} trinuclear units separated by diamagnetic [Cu(NCS)(SCN)3]3− linkers. Compound 3 shows three discrete mononuclear units connected by N-H…N and N-H…S hydrogen bonds. Analysis of XAS proves that the average ligand character and the covalency of the unoccupied metal d-based orbitals for copper(II) and nickel(II) increase in the following order: 1 ® 2 ® 3. In 1 and 2, a weak ferromagnetic coupling between copper(II) and nickel(II) was found, but in 2, additional and stronger antiferromagnetic interaction between copper(II) ions prevailed. Compound 3, as an ionic pair, shows, as expected, a spin-only magnetic moment.

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“…38 More recently, Lin et al have synthesized copper(II)-azido neutral assemblies using polyamine ligands such as triethylenetetramine, diethylenetriamine, and pentamethyldiethylenetriamine hydrothermally using triethyl orthoformate as an acidic buffer to suppress the effective concentrations of these chelating ligands. 34 But in our group we were able to use a more direct approach by using tridentate ligands obtained from the condensation of 2-pyridinecarboxaldehyde with diamines having only one primary amine (while the other side is blocked by alkyl substituents). 27,29 Isolation of these ligands from the condensation reactions was not found to be necessary, so we tried out a reaction, rather boldly, by mixing the aldehyde with a secondary amine [2-{2-(methylamino)ethyl}pyridine] and then introducing this mixture in a waterÀmethanolic solution of copper(II) and excess of azide.…”

Section: Cu 4 Building Unitsmentioning

confidence: 99%

“…The power of this new concept or more appropriately the methodology can be appreciated by the fact that only in the last 3–4 years several new structural topologies were obtained. − Most of these complexes have simple building units, but interestingly their arrangements in the higher dimensions are not necessarily identical. Therefore, we will group only some of the representative complexes based on their nuclearity in the basic units, and discuss the various structural and magnetic consequences of their extended arrangements.…”

Section: Simple Strategy: Complex Structuresmentioning

confidence: 99%

“…The first such complex was obtained rather accidentally by Zhou et al in 2004, in which, although the reaction was carried out with equimolar quantities of copper(II) and diethylenetriammine, the resulting trinuclear complex had in its basic structure one copper(II) atom lacking the chelate . More recently, Lin et al have synthesized copper(II)-azido neutral assemblies using polyamine ligands such as triethylenetetramine, diethylenetriamine, and pentamethyldiethylenetriamine hydrothermally using triethyl orthoformate as an acidic buffer to suppress the effective concentrations of these chelating ligands …”

Section: Cu4 Building Unitsmentioning

confidence: 99%

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Versatility of Azide in Serendipitous Assembly of Copper(II) Magnetic Polyclusters

Mukherjee

2013

Acc. Chem. Res.

121

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Engineering at the molecular level is one of the most exciting new developments for the generation of functional materials. However, the concept of designing polynuclear extended structures from bottom up is still not mature. Although progress has been made with secondary building units (SBUs) in metal organic frameworks (MOFs), the control seems to be just an illusion when it comes to bridging ligands such as the azide ion. When we say that the azido ligand is versatile in its bridging capabilities, what we mean is that it would be difficult to predict or control its bridging properties. However, this kind of serendipity is not always bad news. For example, scientists have shown that the azido ligand can mediate magnetic exchanges between paramagnetic metals in a predictable fashion (usually depending upon the bonding geometries). Therefore, it is a well-respected ligand in polynuclear assemblies. Serendipitous assemblies offer new magnetic structures that we may not otherwise even think about synthesizing. The azido ligand forms a variety of complexes with copper(II) using different blocking amines or pyridine based ligands. Its structural nature changes upon changing the substitution on amine, as well as the amount of blocking ligand. In principle, if we take any of these complexes and provide more coordination sites to the bridging azido ligands by removing a fraction of the blocking ligands, we can get new complexes with intricate structural networks and therefore different magnetic properties with the same components as used for the parent complex. In this Account, we mainly discuss the development of a number of new topological and magnetic exchange systems synthesized using this concept. Not all of these new complexes can be grouped according to their basic building structures or even by the ratio of the metal to blocking ligand. Therefore, we divided the discussion by the nuclearity of the basic building structures. Some of the complexes with the same nuclearities have very similar or even almost identical basic structures. However, the way these building units are joined together (by the azido bridges) to form the overall extended structures differ almost in every case. The complexes having the Cu6 core are particularly interesting from a structural point of view. Although they have almost identical basic structures, some of them are extended in three dimensions, but two of them are extended in two dimensions by two different bridging networks. In the complexes having linear Cu4 basic units, we find that using similar ligands does not always give the same bridging networks even within the basic building structures. These complexes have also enriched the field of molecular magnetism. One of the complexes with a Cu3 building unit has provided us with the opportunity to study the competing behavior of two different kinds of magnetic exchange mechanism (ferromagnetic and antiferromagnetic) acting simultaneously between two metal ions. Through density functional theory calculations, we showed how they work i...

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Cluster‐Based Cu^II–Azide Polymers: Synthesis, Structure, Magnetic Properties, and Effect of Polyamines on Crystal Structures

Cited by 59 publications

References 57 publications

Ground and excited state properties of photoactive platinum(iv) diazido complexes: Theoretical considerations

Ground and excited state properties of photoactive platinum(iv) diazido complexes: Theoretical considerations

Structural Diversity, XAS and Magnetism of Copper(II)-Nickel(II) Heterometallic Complexes Based on the [Ni(NCS)6]4− Unit

Versatility of Azide in Serendipitous Assembly of Copper(II) Magnetic Polyclusters

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Cluster‐Based CuII–Azide Polymers: Synthesis, Structure, Magnetic Properties, and Effect of Polyamines on Crystal Structures

Cited by 59 publications

References 57 publications

Ground and excited state properties of photoactive platinum(iv) diazido complexes: Theoretical considerations

Ground and excited state properties of photoactive platinum(iv) diazido complexes: Theoretical considerations

Structural Diversity, XAS and Magnetism of Copper(II)-Nickel(II) Heterometallic Complexes Based on the [Ni(NCS)6]4− Unit

Versatility of Azide in Serendipitous Assembly of Copper(II) Magnetic Polyclusters

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Cluster‐Based Cu^II–Azide Polymers: Synthesis, Structure, Magnetic Properties, and Effect of Polyamines on Crystal Structures