Sergey N. Konchenko

[{(η5-C5Me5)2Sm}4P8]: A Molecular Polyphosphide of the Rare-Earth Elements

[{(eta(5)-C(5)Me(5))(2)Sm}(4)P(8)], a molecular polyphosphide of the rare-earth elements having a realgar core structure, was synthesized by a one-electron redox reaction of divalent samarocen and white phosphorus.

Mixed‐Metal Lanthanide–Iron Triple‐Decker Complexes with a cyclo‐P5 Building Block

Tripleand multidecker sandwich complexes have been discussed in the last decades for their unique electrical and magnetic properties. The organic spacer between the metals may facilitate intermetallic electronic communication, which has a high potential for molecular electronics. A number of one-dimensional organometallic sandwich molecular wires (SMWs) have been extensively studied. Thus, the multilayer vanadium–arene (Ar) organometallic complexes [Vn(Ar)m], which can be produced in a molecular beam by laser vaporization, are a class of one-dimensional molecular magnets. Ferrocene-based molecular wires have been synthesized in the gas phase and characterized by mass spectroscopy. It was calculated that these compounds have half-metallic properties with 100 % negative spin polarization near the Fermi level in the ground state. In contrast to this investigation in the gas phase, studies on related organometallic tripleand multidecker sandwich complexes containing f-block elements (lanthanides or actinides) in condensed phase remain rare; studies were mostly on the cyclooctatetraene ligand and its derivatives. The only rare-earth-element triple-decker complex with heterocycles is the low-valent scandium 1,3,5-triphosphabenzene complex [{(hP3C2tBu2)Sc}2(m-h 6 :h-P3C3tBu3)], which was obtained by cocondensation of scandium vaporized in an electron beam with an excess of the phosphaalkyne tBuC P. Apart from organometallic compounds, tripleand multidecker sandwich complexes of the 4f elements consisting of “salen” type Schiff base ligands, phthalocyanines, and porphyrins have been extensively studied because these compounds exhibit tunable spectroscopic, electronic, and redox properties, and different extents of intramolecular p–p interactions. Despite these promising physical properties further investigations on 4f elements based tripleand multidecker sandwich complexes are obviously hampered by the limited variety of ligands that have been attached to the metal centers to date. Based on these considerations, we present herein mixed d/f-block-metal triple-decker complexes with a purely inorganic all-phosphorus middle deck. In contrast to d-block chemistry, where purely inorganic ring systems of Group 15 elements such as P5 and P6, [9] As5, [9c] and Sb5 [10] are well-established, there is no analogy with the fblock elements to date. On the other hand, it was shown only recently that rare-earth elements can stabilize highly reactive main-group species such as N2 3 . Although some heavier Group 15–lanthanide compounds, such as phosphides (Ln PR2), [12] arsenides (Ln AsR2), 13] stibides (Ln Sb3), and bismutides (Ln Bi Bi Ln) are known, the first molecular polyphosphide of the rare-earth elements, [(Cp*2Sm)4P8] (Cp* = h-C5Me5), was recently synthesized. [16] The structure of the complex is very rare and can be described as a realgartype P8 4 ligand trapped in a cage of four samarocenes. As no triple-decker sandwich complex of the rare-earth elements with a polyphosphide middle-deck bridging the metal centers is known, we focused our interest on the cyclo-P5 ligand. The structure and properties of this ligand are very similar to the well-known cyclopentadienyl anion (Scheme 1) and could therefore have many possible coordination modes.

Heterospin π-Heterocyclic Radical-Anion Salt: Synthesis, Structure, and Magnetic Properties of Decamethylchromocenium [1,2,5]Thiadiazolo[3,4-c][1,2,5]thiadiazolidyl

Decamethylchromocene, Cr(II)(eta(5)-C(5)(CH(3))(5))(2) (2), readily reduced [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole (1) in a tetrahydrofuran solvent at ambient temperature with the formation of radical-anion salt [2](+)[1](-) (3) isolated in 97% yield. The heterospin salt 3 ([2](+), S = 3/2; [1](-), S = 1/2) was characterized by single-crystal X-ray diffraction as well as magnetic susceptibility measurements in the temperature range 2-300 K. The experimental data together with theoretical analysis of the salts magnetic structure within the CASSCF and spin-unrestricted broken-symmetry (BS) density functional theory (DFT) approaches revealed antiferromagnetic (AF) interactions in the crystalline 3: significant between anions [1](-), weak between cations [2](+), and very weak between [1](-) and [2](+). Experimental temperature dependences of the magnetic susceptibility and the effective magnetic moment of 3 were very well reproduced in the assumption of the AF-coupled [1](-)...[1](-) (J(1) = -40 +/- 9 cm(-1)) and [2](+)...[2](+) (J(2) = -0.58 +/- 0.03 cm(-1)) pairs. The experimental J(1) value is in reasonable agreement with the value calculated using BS UB3LYP/6-31+G(d) (-61 cm(-1)) and CASSCF(10,10)/6-31+G(d) (-15.3 cm(-1)) approaches. The experimental J(2) value is also in agreement with that calculated using the BS DFT approach (-0.33 cm(-1)).

Gallium(I)–alkaline earth metal donor–acceptor bonds

Compounds with a gallium-alkaline earth metal bond, [(eta(5)-C(5)Me(5))(2)Ca-Ga(eta(5)-C(5)Me(5))], [(eta(5)-C(5)Me(5))(2)(THF)Sr-Ga(eta(5)-C(5)Me(5))], and [(eta(5)-C(5)Me(5))(2)Ba-{Ga(eta(5)-C(5)Me(5))}(2)], were prepared.

Bis(toluene)chromium(I) [1,2,5]Thiadiazolo[3,4-c][1,2,5]thiadiazolidyl and [1,2,5]Thiadiazolo[3,4-b]pyrazinidyl: New Heterospin (S1 = S2 = 1/2) Radical-Ion Salts

Bis(toluene)chromium(0), Cr(0)(η(6)-C7H8)2 (3), readily reduced [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole (1) and [1,2,5]thiadiazolo[3,4-b]pyrazine (2) in a tetrahydrofuran solvent with the formation of heterospin, S1 = S2 = ½, radical-ion salts [3](+)[1](-) (4) and [3](+)[2](-) (5) isolated in high yields. The salts 4 and 5 were characterized by single-crystal X-ray diffraction (XRD), solution and solid-state electron paramagnetic resonance, and magnetic susceptibility measurements in the temperature range 2-300 K. Despite the formal similarity of the salts, their crystal structures were very different and, in contrast to 4, in 5 anions were disordered. For the XRD structures of the salts, parameters of the Heisenberg spin Hamiltonian were calculated using the CASSCF/NEVPT2 and broken-symmetry density functional theory approaches, and the complex magnetic motifs featuring the dominance of antiferromagnetic (AF) interactions were revealed. The experimental χT temperature dependences of the salts were simulated using the Van Vleck formula and a diagonalization of the matrix of the Heisenberg spin Hamiltonian for the clusters of 12 paramagnetic species with periodic boundary conditions. According to the calculations and χT temperature dependence simulation, a simplified magnetic model can be suggested for the salt 4 with AF interactions between the anions ([1](-)···[1](-), J1 = -5.77 cm(-1)) and anions and cations ([1](-)···[3](+), J2 = -0.84 cm(-1)). The magnetic structure of the salt 5 is much more complex and can be characterized by AF interactions between the anions, [2](-)···[2](-), and by both AF and ferromagnetic (FM) interactions between the anions and cations, [2](-)···[3](+). The contribution from FM interactions to the magnetic properties of the salt 5 is in qualitative agreement with the positive value of the Weiss constant Θ (0.4 K), whereas for salt 4, the constant is negative (-7.1 K).

Intramolecular phosphorus-phosphorus bond formation within a Co2P4 core.

The reduction of [(Cp‴Co)2(μ,η(2:2)-P2)2] (Cp‴ = 1,2,4-tBu3C5H2) with the samarocenes, [(C5Me4R)2Sm(THF)n] (R = Me or n-propyl), gives [(Cp‴Co)2P4Sm(C5Me4R)2]. This is the first example of an intramolecular P-P coupling in a polyphosphide complex upon reduction of the transition metal. The formation of the P-P bond is not a result of the direct reduction of the phosphorus atoms but is induced by a rearrangement of the positive charges between the metal atoms.

Optically active ZnII and PtII complexes of the 3-carene type α-amino oxime

Abstract (1S,3S,6R)-3- N,N- Dimethylaminocaran-4-one E-oxime forms stable 1:1 chelate complexes with ZnCl2 and PtCl2 whose structures are supported by X-ray, 1H, 13C, 14N and 195Pt NMR data. The conformation of the six-membered carbon cycle in the complexes was found to be changed as compared to the starting compound.

Hunting for the Magnesium(I) Species: Formation, Structure, and Reactivity of some Donor‐Free Grignard Compounds

Magnesium bromide radicals have to be prepared as high-temperature molecules and trapped as a metastable solution because a seemingly simple reduction of donor-free Grignard compounds failed. However, the essential role of magnesium(I) species during the formation of Grignard compounds could be demonstrated experimentally.

Sterically induced reductive linkage of iron polypnictides with bulky lanthanide complexes by ring-opening of THF

Reduction of [Cp*Fe(η5-E5)] (E = P, As) with divalent lanthanide reagents usually leads to reduction of [Cp*Fe(η5-E5)] followed by a Ln-E bond formation. In contrast, by using the sterically encumbered reagent [(DippForm)2Sm(thf)2] (DippForm = {(2,6-iPr2C6H3)NC(H)[double bond, length as m-dash]N(2,6-iPr2C6H3)}-), ring-opening of thf and reduction of the polypnictide is observed. This leads to two new 3d/4f polyphosphide or polyarsenide complexes [(DippForm)2Sm(Cp*Fe)E5{(CH2)4O}{(DippForm)2Sm(thf)}], in which [(DippForm)2Sm(thf)2] and [Cp*Fe(η5-E5)] are linked by a ring-opened thf molecule and no Ln-E bond formation is observed.

Synthesis of extended acyclic azathienes. Crystal and molecular structure of two compounds, Ar(SNSN)nSiMe3 (Ar 2-O2NC6H4; n 1,2)

Abstract The 1:1 reaction of (Me3SiNSN)2S with ArSCl gives Ar(SNSN)2SiMe3, while the 1:2 reaction gives (ArSN)2S and (SN)4 if Ar = Ph, and (ArSNSN)2S if Ar = nitrophenyl. Thus, the aromatic nitro groups inhibit spontaneous shortening of azathiene chains of (ArSNSN)2S, but they do not stabilize the compounds containing a chain of 17 alternating nitrogen and sulphur atoms [Ar(SNSN)2SiMe3 + SCl2, 2:1] which are shortened to (ArSNSN)2S. As shown by X-ray structure analysis, the configuration of the azathiene chains in the compounds Ar(SNSN)nSiMe3 (Ar = 2- O2NC6H4; n = 1, 2) is similar to that of (SN)x macromolecules: Z, E, n = 1; Z, E, Z, E, n = 2. At n = 1 the molecule is planar, at n = 2 (the longest oligomer azathiene chain with established real geometry) the non-hydrogen atoms lie on the cylindrical surface with a radius of ca 50 A.