Synthesis and crystal structure of [N,N′-bis(2,3,5,6-tetrafluorophenyl)-ethane-1,2-diaminato(2-)]dipyridineplatinum(II)

The reaction of PtCl₂en (en = ethane-1,2-diamine) with TlO₂CC₆F₅ in boiling pyridine unexpectedly yielded a polyfluorophenyl-stabilized ethane-1,2-diaminatoplatinum(II) complex, Pt[N(p-HC₆F₄)CH₂]₂(py)₂, 1a, the structure of which has been established by X-ray crystallography.     

N- versus P-coordination in bis(amino)cyclodiphosph(III)azane complexes of aluminum

The reaction of the bis(amino)cyclodiphosph(III)azane, cis-{(tBuNH)(2)(PNtBu)(2)}, with AlMe(3), AlClMe(2), AlCl(2)Me, and AlCl(3) is reported. The less Lewis acidic compound AlMe(3) forms the adduct cis-[(tBuNH)(2)(PNtBu){P.(AlMe(3))NtBu}] (1), in which the aluminum atom is exclusively coordinated to one phosphorus atom. At elevated temperatures AlMe(3) undergoes migratory exchange between the two phosphorus atoms, but no methane elimination is observed. By using the more Lewis acidic compound AlClMe(2) the P-coordinated compound cis-[(tBuNH)(2)(PNtBu){P(AlClMe(2))NtBu}] (2) can be obtained at low temperatures. Compound 2 rearranges irreversibly to a product in which the AlClMe(2) group is coordinated by one exo-cyclic nitrogen atom. A concomitant 1,2-H shift from this nitrogen atom onto the phosphorus atom is observed. The N-coordinated rearrangement product slowly decomposes via a P-N bond cleavage in solution. Reaction of the even more Lewis acidic compounds AlCl(2)Me and AlCl(3) finally led to stable adducts, cis-[(tBuNH)(PNtBu)(tBuNAlCl(2)Me){P(H)NtBu}] (3), and cis-[(tBuNH)(PNtBu)(tBuNAlCl(3)){P(H)NtBu}] (4), in which the aluminum atoms are N-coordinated by a tBuN=PH unit.     

Chlorobis(nitrato‐O,O')(tetraethylene glycol dimethyl ether)neodymium(III), [NdCl(NO3)2(tetraglyme)]: A Novel Heteroleptic Complex

In the crystal structure of [NdCl(NO₃)₂(tetraglyme)] (triclinic, P1, Z = 2, a = 7.814(1); b = 7.9832(9); c = 15.322(2) Å; α = 87.38(1); β = 84.88(1); γ = 79.83(1)°), neodymium is ten coordinate with two transoid chelating nitrate ligands, a chlorine and the five oxygen atoms of the tetraglyme ligand in an irregular array.     

Molecular and Crystal Structures of CpSmX2(THF)3 (X = Br,I)

The reaction of Cp₂Sm(THF) with 1,2-dibromoethane or 1,2-diiodoethane leads to an equimolar mixture of Cp₃Sm(THF) and CpSmX₂(THF)₃ (X = Br, I). CpSmBr₂(THF)₃ crystallizes in the monoclinic system (P2₁, Z = 2, a = 804.6(1), b = 1507.6(2), c = 913.8(1) pm, β = 107.36(1)°, R₁ = 0.0327, wR₂ = 0.0578), while CpSmI₂(THF)₃ is orthorhombic (Pna2₁, Z = 4, a = 1950.6(3), b = 1377.1(2), c = 831.93(9) pm, R₁ = 0.0438, wR₂ = 0.0412). The ligand arrangement around the formally eight coordinate Sm atom is a distorted octahedron with the centroid of the Cp-ring and one THF-molecule in the apical positions, whilst the halides are transoid in the equatorial plane.     

Molecular and Crystal Structures of Cp2YbX(THF) (X = Cl,Br)

Cp₂YbCl(THF) crystallizes in the orthorhombic space group Pnma (Z = 4, a = 13.109(5), b = 11.851(4), c = 9.377(3) Å, R1 = 0.0412, wR2 = 0.0482), while Cp₂YbBr(THF) is monoclinic (P2₁/n, Z = 4, a = 8.149(2), b = 12.997(2), c = 14.388(3) Å, β = 105.73(2)°, R1 = 0.0425, wR2 = 0.0436). The ligand arrangements around the formally eight coordinate Yb atoms are pseudo tetrahedral. These two determinations complete the first series of [Cp₂LnX(L)] (X = F, Cl, Br, I) structures covering all halogens for one lanthanoid and cyclopentadienyl group.     

Two Dieneplatinum Synthetic Reagents,Pt(C6H2F3‐2,4,6)2(cod) and Pt(C6HF4‐2,3,4,5)2(cod)

Reactions of PtCl₂(cod) (cod = cycloocta‐1,5‐diene) with 2,4,6‐trifluoro‐ and 2,3,4,5‐tetrafluoro‐phenyllithium in diethyl ether gives Pt(C₆H₂F₃‐2,4,6)₂(cod) ( 1 ) (monoclinic, P2₁/n, Z = 4, a = 7.141(1), b = 15.002(2), c = 17.071(3) Å, β = 91.37(2)°) and Pt(C₆HF₄‐2,3,4,5)₂(cod) ( 2 ) (triclinic, P 1, Z = 2, a = 10.150(2), b = 10.762(2), c = 10.812(2) Å, α = 63.606(3), β = 63.327(3), γ = 76.496(3)°) respectively, which have two ipso carbon atoms and two double bond midpoint centres in a square planar arrangement, and aromatic rings angled near perpendicular to the coordination plane.     

Reinvestigation of Reactions of HgPh2 with Eu and Yb Metal and the Synthesis of a Europium(II) Bis(tetraphenylborate)

Europium bis(tetraphenylborate) [Eu(thf)₇][BPh₄]₂⋅thf containing a fully solvated [Eu(thf)₇]²⁺ cation, was synthesized by protolysis of “EuPh₂” (from Eu and HgPh₂) with Et₃NHBPh₄, and the structure was determined by single-crystal X-ray diffraction. Efforts to characterize the putative “Ph₂Ln” (Ln = Eu, Yb) reagents led to the synthesis of a mixed-valence complex, [(thf)₃Yb^II(μ-Ph)₃Yb^III(Ph)₂(thf)]⋅2thf, resulting from the reaction of Yb metal with HgPh₂ at a low temperature. This mixed-valence Yb^II/Yb^III compound was studied by ¹⁷¹Yb-NMR spectroscopy and single-crystal X-ray diffraction, and the oxidation states of the Yb atoms were assigned.     

Chalcogen Bonds in Selenocysteine Seleninic Acid,a Functional GPx Constituent,and in Other Seleninic or Sulfinic Acid Derivatives

The controlled oxidation reaction of L-selenocystine under neutral pH conditions affords selenocysteine seleninic acid (3-selenino-L-alanine) which is characterized also by means of single-crystal X-ray diffraction. This technique shows that selenium forms three chalcogen bonds (ChBs), one of them being outstandingly short. A survey of seleninic acid derivatives in the Cambridge Structural Database (CSD) confirms that the C−Se(=O)O− functionality tends to act as a ChB donor robust enough to systematically influence the interactional landscape in the solid. Quantum Theory of Atom in Molecules (QTAIM) analysis proves the attractive nature of the short contacts observed in crystals containing the seleninic functionality and calculation of surface molecular electrostatic potential (MEP) reveals that remarkably positive σ-holes can frequently be found opposite to the covalent bonds at selenium. Both CSD searches and QTAIM and MEP approaches show that also the sulfinic acid moiety can function as a ChB donor, albeit less frequently than the seleninic acid one. These findings may contribute to a better understanding, at the atomic level, of the mechanism of action of the enzymes that control oxidative stress and ROS deactivation and that contain selenocysteine seleninic acid and cysteine sulfinic acid in the active site.