Synthesis and Characterization of Di- and Trivalent Pyrazolylborate β-Diketonates and Cyanometalates

Abstract

The syntheses, structures, and magnetic properties of a series of di- and trivalent hydridotris(3,5-dimethylpyrazol-1-yl)borate (Tp*) cyanomanganates are described. Treatment of tris(acetylacetonate)manganese(III) [Mn(acac)(3)] with KTp* and tetra(ethyl)ammonium cyanide affords [NEt(4)][(Tp*)Mn(II)(κ(2)-acac)(CN)] (1), as the first monocyanomanganate(II) complex; attempted oxidation of 1 with iodine affords {(Tp*)Mn(II)(κ(2)-acac(3-CN))}(n) (2) as a one-dimensional chain and bimetallic {[NEt(4)][(Tp*)Mn(II)(κ(2)-acac(3-CN))](2)(μ-CN) (3) as the major and minor products, respectively. A fourth complex, [NEt(4)][(Tp*)Mn(II)(η(2)-acac(3-CN))(η(1)-NC-acac)] (4), is obtained via treatment of Mn(acac(3-CN))(3) with KTp* and [NEt(4)]CN, while [NEt(4)](2)[Mn(II)(CN)(4)] (5) was prepared from manganese(II) trifluoromethanesulfonate and excess [NEt(4)]CN. Tricyanomanganate(III) complexes, [cat][(Tp*)Mn(III)(CN)(3)] [cat = NEt(4)(+), 7; PPN(+), 8], are prepared via sequential treatment of Mn(acac(3-CN))(3) with KTp*, followed by [NEt(4)]CN, or [cat](3)[Mn(III)(CN)(6)] with (Tp*)SnBu(2)Cl. Magnetic measurements indicate that 1, 2, and 4 contain isotropic Mn(II) (S = (5)/(2); g = 2.00) centers, and no long-range magnetic ordering is found above 1.8 K. Compounds 7 and 8 contain S = 1 Mn(III) centers that adopt singly degenerate spin ground states without orbital contributions to their magnetic moments.

Structure‐Property Relationships in Tricyanoferrate(III) Building Blocks and Trinuclear Cyanide‐Bridged Complexes

“…Under ideal C 3 v symmetry the Fe III LS ions adopt ( z 2 ) 2 ( xz , yz ) 3 electronic configurations, which leads to doubly degenerate 2 E states, rather than triply degenerate ( xz , yz , xy ) 5 or 2 T 2g states, expected under O h symmetry , , , , . The relative energies of the metal‐based orbitals are: z 2 < ( xz , yz ) < ( x 2 – y 2 , xy ),, which was previously confirmed by density‐functional theory calculations of structurally related [(Tp*)Mn III (CN) 3 ] – anions. We note that C 3 v ‐symmetric tricyanomanganate(III) ions adopt an isotropic 3 A 2 state rather than a magnetically anisotropic 3 T 2g one seen for octahedral [Mn III LS (CN) 6 ] 3– , , , , , ,…”

Design of Redox-Active Cs⊂{Fe4Ni4} Cyanide-Bridged Cage Complexes Bearing Monodentate Ligands: Synthesis, Structure, and Electronic Properties

“…Blocked cyanido-complexes [M­(L)­(CN) x ] − were specifically designed and used to target such low-dimensional complexes. − For instance, researchers from our group prepared the fac -[Fe III (Tp)­(CN) 3 ] − (Tp = hydro-tris­(pyrazol-1-yl-borate) which has been extensively used since then together with its derivates fac -[Fe III (RTp)­(CN) 3 ] − (RTp are tris­(pyrazol-1-yl-borate derivatives) . Herein, the choice of blocking ligand, L, is crucial as it affects the metallo-ligand’s electronic properties and topology and thus allows controlling the architecture and properties of the assembled complexes. ,, However, also synthetic conditions may drastically influence the resulting topology.…”

Titanium(III) Member of the Family of Trigonal Building Blocks with Scorpionate and Cyanide Ligands

“…This ligand is appealing because of its trigonal symmetry and ease of substitution, which allows for fine tuning of the electronic and steric properties of the ligand. The Tp ligand and its derivatives have been used with success to isolate the tricyanide anionic building block [TpFe III (CN) 3 ], which has been used to prepare numerous magnetically interesting polynuclear complexes. − Other 3d transition metals have been employed as well to synthesize trivalent Cr, Mn, and V and divalent Fe tricyanide complexes. − Dicyanide molecules containing divalent Ni, Co, and Cr ions, as well as monocyanide molecules with divalent Zn and Hg ions have also been reported. − To the best of our knowledge, no cyanide-containing molecules with Ti metal ions and Tp, or its derivatives, have been reported to date.…”