Ein Aufbaumodell für „Chimney-Ladder“-Strukturen

On the basis of a concept of inhomogeneous linear structure series a model for the Chimney-LadderNowotny phases is proposed. All the phases can be explained as members of a structural series of general formulaT _p+2q+3r B _2p+2q+4r ,T-transition metal of 5–7 groups,B-Al, Ga, Si, Ge, Sn. The real and possible hypothetical members of this series are described by the symmetry of 21 monoclinic, orthorhombic and tetragonal space groups. The structure types for Tc₄Si₇ and Mo₉Ge₁₆ have been proposed.

     

Nitrosylation of Hexafluoridotechnetate(IV)

Potassium hexafluoridotechnetate(IV), K₂[TcF₆], slowly reacts in aqueous solution with acetohydroxamic acid with formation of the ammine nitrosyltechnetium(I) complex [Tc(NO)(NH₃)₄F]⁺. The product crystallizes as mixed TcF₆^2–/HF₂^– salt of the composition [Tc(NO)(NH₃)₄F]₄[TcF₆][HF₂]₂. [Tc(NO)(NH₃)₄F]⁺ represents the first nitrosyltechnetium complex with a fluorido ligand in its coordination sphere. The Tc–F bonds in two crystallographically independent species are 1.987(2) and 2.034(2) Å, respectively. This is slightly longer than in the [TcF₆]^2– counterion.     

Syntheses and Structures of Nitridorhenium(V) and Nitridotechnetium(V) Complexes with N,N‐[(Dialkylamino)(thiocarbonyl)]‐N′‐(2‐hydroxyphenyl)benzamidines

[MNCl₂(PPh₃)₂] complexes (M = Re, Tc) react with N‐[(dialkylamino)(thiocarbonyl)]‐N′‐(2‐hydroxyphenyl)benzamidines (H₂L¹) with formation of neutral, five‐coordinate nitrido complexes of the composition [MN(L¹)(PPh₃)]. The products have distorted square‐pyramidal coordination spheres with each a tridentate, double‐deprotonated benzamidine and a PPh₃ ligand in their basal planes.     

Phenylimido Complexes of Technetium and Rhenium with Maleonitriledithiolate

[Tc(NPh)Cl₃(PPh₃)₂] or [Re(NPh)Cl₃(PPh₃)₂] react with two equivalents of Na₂mnt (mnt^2– = 1,2‐dicyanoethene‐1,2‐dithiolate) with formation of anionic complexes of the composition [M(NPh)(mnt)₂]^–. The products can be isolated as large red blocks of their AsPh₄⁺ salts. The complex anions contain square‐pyramidal coordinated metal atoms with the phenylimido ligands in apical positions. The M–N–C bonds are almost linear. A similar phenylimido complex with an additional amino group was synthesized from [Re(NC₆H₄‐4‐NH₂)Cl₃(PPh₃)₂]. The presence of such substituents may allow coupling of the metal complexes to biomolecules such as peptides, proteins, or sugars, provided the M=N bonds are sufficiently stable against hydrolysis.     

Nitridorhenium(V) and nitridotechnetium(V) complexes with 2-(diphenylphoshinomethyl)aniline

Reactions of 2-(diphenylphosphinomethyl)aniline, H₂L¹, with [MNCl₂(PPh₃)₂] complexes (M = Re, Tc) give the bis-chelates [MNCl(H₂L¹)₂]Cl (M = Re, Tc) or the mono-chelate [ReNCl₂(PPh₃)(H₂L¹)] depending on the conditions applied. The aminophosphine reacts as a bidentate, neutral ligand in all three cases. The complexes were studied spectroscopically and by X-ray crystallography.     

trans‐[TcNCl2(Ph3PNH)2] — Synthesis and Structure

The neutral technetium(V) phosphoraneimine complex [TcNCl₂(Ph₂PNH)₂] is formed when (Bu₄N)[TcOCl₄] reacts with Me₃SiNPPh₃ in dichloromethane. Distances of 2.078(4) and 2.102(4) Å have been found between Tc and the neutral triphenylphosphoraneimine ligands. The Tc‐N‐P angles are 133.7(3) and 134.8(3)°. The terminal nitrido ligand is formed by decomposition of an additional molecule of Me₃SiNPPh₃. The protons which are used for the protonation of the organic ligands are released during the decomposition of CH₂Cl₂. The same reaction yields the [TcNCl₄]^— anion when it is performed in acetonitrile.