Synthesis and structure determination of Co(HNCN)2 and Ni(HNCN)2

Well-crystallized cobalt and nickel hydrogencyanamide, Co(HNCN)₂ and Ni(HNCN)₂, were synthesized from the corresponding ammonia complexes [M(NH₃)₆]²⁺ under aqueous cyanamide conditions. The X-ray and neutron powder data evidence the orthorhombic system and space group Pnnm. The cell parameters for Co(HNCN)₂ are a=6.572(1), b=8.805(2), c=3.267(1) Å, and Z=2; for the isotypic Ni(HNCN)₂, the cell parameters arrive at a=6.457(1), b=8.768(2), c=3.230(1) Å. The octahedral coordinations of the metal ions are marginally squeezed, with interatomic distances of 4×Co-N=2.134(5) Å, 2×Co-N=2.122(9) Å, and 4×Ni-N=2.133(6) Å, 2×Ni-N=2.035(11) Å. The HNCN⁻ units appear as slightly bent (177.5(2)° for Co(HNCN)₂ and 175.7(2)° for Ni(HNCN)₂) and exhibit cyanamide shape character due to triple- and single-bond C-N distances (1.20(2) vs. 1.33(2) Å for Co(HNCN)₂ and 1.15(2) vs. 1.38(2) Å for Ni(HNCN)₂). The infrared vibration data compare well with those of the three existing alkali-metal hydrogencyanamides.     

LiM2(NCN)Br3 (M = Sr,Eu): Synthesis and Crystal Structures of Solid‐State Carbodiimides with Empty Tetrahedral Metal Entities

Two solid‐state carbodiimide compounds, LiM₂(NCN)Br₃ (M = Sr, Eu), with characteristic empty tetrahedral M₄ entities have been synthesized using a flux route, and their structures were determined by single‐crystal X‐ray diffraction. The new phases LiSr₂(NCN)Br₃ and LiEu₂(NCN)Br₃ are isotypical with the corresponding iodides and crystallize in the cubic system (( , Z = 16) but with smaller unit cells (a = 14.641(1) Å for LiSr₂(NCN)Br₃ and 14.572(1) Å for LiEu₂(NCN)Br₃). The extended structures comprise two interpenetrating three‐dimensional networks: the first one is built from isolated M₄ tetrahedra capped by NCN^2? anions on their triangular faces while the second is made from vertex‐sharing LiBr₆ octahedra. The linear NCN^2? anions exhibit the symmetrical carbodiimide shape and serve as linkers between the tetrahedral entities.     

One-pot synthesis of 1-substituted-5-alkylselanyl-1H-tetrazoles from isoselenocyanates: unexpected formation of N-alkyl-N-arylcyanamides and (Z)-Se-alkyl-N-cyano-N,N′-diarylisoselenoureas

1-Substituted-5-alkylsulfanyl-1H-tetrazoles are well known class of organic substances with various applications in medicinal chemistry or photographic industry. Their selenium analogues, 1-substituted-5-alkylselanyl-1H-tetrazoles are, however, much less explored because of the lack of suitable methods for their preparation. In this work we investigated the synthesis of 1-alkyl/aryl-5-alkylselanyl-1H-tetrazoles from synthetically available alkyl/arylisoselenocyanates. One-pot reactions of arylisoselenocyanates with sodium azide and alkylating agent led to the target 5-alkylselanyl-1-aryl-1H-tetrazoles but also to interesting side products, namely N-alkyl-N-arylcyanamides and (Z)-Se-alkyl-N-cyano-N,N′-diarylisoselenoureas. Nevertheless, when alkylisoselenocyanates were utilized as the substrates, the reactions led exclusively to the formation of 1-alkyl-5-alkylselanyl-1H-tetrazoles in good yields. This simple one-pot procedure brings new possibilities for the preparation of variously substituted selenium compounds. It also opens the way to further investigations of selenium isosteres of the widely utilized 5-thiotetrazole moiety in biomedical applications.     

Reactivity with Amines of Bis(cyanamide) and Bis(cyanoguanidine) Complexes of the Iron Triad

Treatment of bis(cyanamide) [M(N≡CNEt₂)₂L₄](BPh₄)₂ and bis(cyanoguanidine) [M{N≡CN(H)C(NH₂)=NH}₂L₄](BPh₄)₂ complexes [M = Fe, Ru, Os; L = P(OEt)₃] with an excess of amine RNH₂ (R = nPr, iPr) affords mixed‐ligand complexes with cyanamide and amine [M(NH₂R)(N≡CNEt₂)L₄](BPh₄)₂ ( 1a – 5a ) and [M(NH₂R){N≡CN(H)C(NH₂)=NH}L₄](BPh₄)₂ ( 1b , 2b ). The complexes were characterized by spectroscopy and X‐ray crystal structure determination of [M(NH₂iPr)(N≡CNEt₂){P(OEt)₃}₄](BPh₄)₂ [M = Ru ( 3a ), Os ( 5a )].     

Synthesis and Crystal Structure of Bis (Tetrabutylammonium)(4,4′-Azodi(phenylcyanamide)) Salt · [(<Emphasis Type="Italic">n</Emphasis>-Bu)<Subscript>4</Subscript>N]<Subscript>2</Subscript>[Azodicyd<Superscript>2−</Superscript>] · H<Subscript>2</Subscript>O

Abstract The chemical preparation and crystal structure for a 4,4′-azodi(phenylcyanamide) salt) in the solid state are reported. This compound crystallizes in the triclinic space group P with the following unit cell parameters: a = 9.759(3) ?, b = 11.237(4) ?, c = 11.919(4) ?, α = 95.54(3)°, β = 98.50(3)°, γ = 109.39(2)°, Z = 1 and V = 1204.4(7) ?³. The 4,4′-azodi(phenylcyanamide) dianion, azodicyd²⁻, is approximately planar, with the cyanamide groups (–N=C=N) in an anti conformation relative to each other and the azo group (–N=N–) adopting the more thermodynamically stable trans conformation. The crystal X-ray analysis shows that there are one azo molecule cation, two tetrabutylammonium cations and one water molecule in unit cell. Intermolecular O–H···N hydrogen bonds may be effective in the stabilization of the crystal structure of this compound and to form linear chain structure in the packing. Index Abstract Synthesis and crystal structure of Bis (Tetrabutylammonium)(4,4′-Azodi(phenylcyanamide)) salt . [(n-Bu)4N]2[Azodicyd^2-] · H₂O Davar M. Boghaei ^1*, Fatemeh Behzadian-Asl ¹ and Hamid Reza Khavasi^{2 1} Department of Chemistry, Sharif University of Technology, P.O. Box 11155-9616, Tehran, Iran ² Department of Chemistry, Shahid Beheshti University, Evin, Tehran 1983963113, Iran Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Efficient acid catalytic synthesis of pyrazolopyrimidines from 1H-pyrazol-5-yl-N,N-dimethylformamidines with cyanamide

The efficient acid catalytic synthesis of pyrazolo [3,4-d]pyrimidine was developed by treating 1H-pyrazol-5-yl-N,N-dimethylformamidine with various aminating agents including N,O-bis(trimethylsilyl)hydroxylamine (NHSiMe₃(OSiMe₃)), cyanamide (NH₂CN), hydroxylamine (NH₂OH), methoxyamine (NH₂OMe), hydrazine (NH₂NH₂), and urea (NH₂C(O)NH₂) in acidic solution at reflux. Based on the experimental result, cyanamide (NH₂CN) and methanesulfonic acid were indicated the best aminating agent and acid mediated solvent. On the other hands, the reactivity tendency was involved the activity of original leaving species grafting on the aminating agents, such as –OH, –OMe, –OSiMe₃, –NH₂, –OSiMe₃, –C(O)NH₂, and –CN, in acid catalytic heterocyclic reaction.     

Solid State Metathesis Reactions in Various Applications

Solid state metathesis reactions have been studied in fused silica tubes, by differential thermal analysis, and by X‐ray powder diffraction. A selection of reactions between metal (La, Nb, and Ni) chlorides and lithium nitride or lithium acetylide were investigated to get more insight into reaction pathways and intermediate reaction stages that may be adopted on course of the formation of metal nitrides or carbides. Intermediate compounds are considered to be important because they can control the reactivity of a system. Such compounds were traced by changing the molar ratios of reaction partners away from the salt‐balanced binary metal nitride or carbide target compositions. New preparative perspectives are discovered when metal chlorides were reacted with lithium nitridoborate or lithium cyanamide. Due to their reductive nature towards several d‐block metal chlorides, (BN₂)^3‐ and (CN₂)^2‐ react to form metals or metal nitrides plus X‐ray amorphous BN, and probably C₃N₄. With lanthanum chloride they can react to form nitridoborates and nitridocarbonates. The metathesis reaction between lithium cyanamide and cyanuric chloride (C₃N₃Cl₃) instead of metal chloride was studied for the synthesis of C₃N₄.     

EuCN2 — The First,but Not Quite Unexpected Ternary Rare Earth Metal Cyanamide

Red‐orange, transparent single crystals of EuCN₂ (Pnma (62), a = 1232.41(9), b = 395.26(3) and c = 539.43(4) pm, Z = 4) are obtained by the reaction of EuN, C and NaN₃ in arc‐welded Ta ampoules at 1300 K. The first ternary rare earth metal cyanamide is isotypic to α‐SrCN₂ and shows the characteristic frequencies for the CN₂^2— unit in the optical spectra (ν_s = 1244; ν_as = 1969 and 2087; δ = 655 / 666 cm^—1).