Search

2,2′‐Bipyrazine (2,2′‐bpz) reacts with cis‐(NH3)2PtIIin water to give a variety of products, several of which were isolated and characterized by X‐ray analysis: cis‐[Pt(NH3)2(2,2′‐bpz‐N4)2](NO3)2⋅3 H2O (1), [{cis‐Pt(NH3)2(2,2′‐bpz‐N4,N4′)}3](PF6)5NO3⋅7 H2O (2 a), [{cis‐Pt(NH3)2(2,2′‐bpz‐N4,N4′)}3](BF4)2(SiF6)2⋅15 H2O (2 b), and [{cis‐Pt(NH3)2(2,2′‐bpz‐N4,N4′)}4](SO4)4⋅22 H2O (3). In 1, 2 b, and 3the 2,2′‐bpz ligands adopt approximately C2hsymmetries, hence the two pyrazine halves are in transorientation, whereas in 2 aall three 2,2′‐bpz bridges are approximately C2vsymmetric, with the pyrazine halves cisto each other. The topologies of the two triangular complexes 2 aand 2 bare consequently distinctly different, but nevertheless both cations act as hosts for anions. In 2 aa PF6−and a NO3−anion are associated simultaneously with the +6 cation, whereas in 2 bit is a BF4−anion and a water molecule, which are trapped in its cavity. There is no anion inclusion in case of the metallasquare 3. In principle, 3can exist in a large number of stereoisomers, depending on the rotational states of the bridging 2,2′‐bpz ligands. Isolation of a single rotamer form of 3with C2hsymmetric 2,2′‐bpz ligands and an overall mesoform is proposed to be a consequence of a highly efficient self‐assembly process that starts from the precursor 1and reaction with two cis‐(NH3)2PtIIunits. This process leads to the isolated rotamer of 3regardless of whether two cations 1in head–head form react with two cis‐(NH3)2PtII, or whether the Δ enantiomer of the chiral head–tail form of 1combines with its Λ enantiomer through two cis‐(NH3)2PtIIentities.

The reaction of silver perchlorate with [PhI2SnCH2([16]crown‐5)] (1) and [I3SnCH2([16]crown‐5)] (2) gave the organotin(IV)‐substituted crown ether complexes [PhSnCH2([16]crown‐5)][ClO4]2(3) and [HOSnCH2([16]crown‐5)][Y]2(4: Y=ClO4, 5: Y=CF3SO3), respectively. All compounds have been isolated as air‐stable materials and characterised by 1H, 13C, 119Sn and 119Sn MAS (5) NMR spectroscopy, ESIMS spectrometry, elemental analysis and by single‐crystal X‐ray diffraction analysis. The molecular structures of 3–5show that the tin(IV) cation fits perfectly into the crown ether cavity and is coordinated by the five oxygen atoms of the ring to give a pentagonal bipyramidal configuration about the central metal cation. Notably, compounds 4and 5contain the first monomeric monoorganotin dication. Moreover, there are 3J(1H,119Sn) coupling constants to the CH2CHproton of 377 (3) and 470 Hz (4, 5) that are, to the best of our knowledge, the biggest such couplings ever reported.

Broad spectrum: Novel para‐functionalized aryl‐di‐tert‐butylfluorosilanes, p‐(tBu2FSi)C6H4X (X=functional group), have been made available and broaden the spectrum of silicon‐based 18F acceptors (SiFAs) for potential PET applications. For example, the [18F]maleimido derivative 1has been employed for the synthesis of [18F]1‐ labeled rat serum albumin (RSA), the applicability of which for PET has been verified by in vivo experiments.

Acid‐catalysed hydrolysis of [CH2{Sn(Ph2)CH2Si(OiPr)Me2}2] followed by subsequent reaction with mercuric chloride in acetone afforded the novel silicon‐ and tin‐containing eight‐membered ring [cyclo‐CH2{Sn(Cl2)CH2Si(Me2)}2O] in good yield, the crystal structure of which is reported. 119Sn NMR and X‐ray studies indicate that [cyclo‐CH2{Sn(Cl2)CH2Si(Me2)}2O] acts as a bidentate Lewis acid towards chloride ions exclusively forming the 1:1 complex [(Ph3P)2N]+[cyclo‐CH2{Sn(Cl2)CH2Si(Me2)}2OCl]−upon addition of [(Ph3P)2N]+Cl−. Also reported are the synthesis and structure of [K(dibenzo[18]crown‐6)]+[cyclo‐CH2{Sn(Cl2)CH2Si(Me2)}2OF]−, the first completely characterised organostannate with a C2SnCl2F‐substituent pattern. No ring‐opening polymerisation could be achieved for [cyclo‐CH2{Sn(Cl2)CH2Si(Me2)}2O] or for its perphenylated derivative [cyclo‐CH2{Sn(Ph2)CH2Si(Me2)}2O]. The reaction of [cyclo‐CH2{Sn(Cl2)CH2Si(Me2)}2O] with Me3O+BF4−gave the tin‐containing fluorosilane [CH2{Sn(Cl2)CH2Si(F)Me2}2], in which the Si−F bond is activated by intermolecular Si−F⋅⋅⋅Sn interactions in the solid state.