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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 synthesis of the intramolecularly coordinated pentacarbonyltungsten–organostannylene complexes {2,6‐(Me2NCH2)2C6H3}Sn(H)W(CO)5(2) and [{2,6‐(Me2NCH2)2C6H3}Sn(μ‐OH)W(CO)5]2(3) and the solid‐state molecular structure of 3, as determined by single‐crystal X‐ray diffraction analysis, are reported. Compound 3is characterized by hydroxido bridges [Sn–O 2.068(5), 2.231(5) Å], an intramolecular N→Sn coordination bond [2.501(7) Å] and an intramolecular O–H···N hydrogen bond [O···N 2.715(8) Å].

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.

The molecular structures of the intramolecularly coordinated tungstenpentacarbonyl organostannylene complexes 2,6Me2NCH22C6H3ClSnWCO5and [2,6Me2NCH22C6H3H2OSnWCO5]+CB11H12–are reported. The latter compound is an aqua complex in which the water molecule replaces one of the two N→Sn coordination sites. The coordination of the water molecule is accompanied by proton transfer to the nitrogen atom. DFT calculations reveal this to be the thermodynamically moststable structure.

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.

Single crystal X‐ray diffraction analyses of LSn(OCH2CH2)2NR [1, R = Me, L = lone pair; 2, R = Me, L = W(CO)5; 3, R = t‐Bu, L = W(CO)5] reveal these compounds to be dimeric and cis‐configurated. The dimerization is realized by intramolecular O→Sn interactions to give four‐membered Sn2O2‐rings. In addition, there are intramolecular N→Sn interactions ranging in between 2.356(5) (2) and 2.549(4) Å (3).

The hypercoordinated di- and triorganotin(IV) chlorides [{2-(Me2NCH2)C6H4}2SnCl2] (1a) and [{2-(Me2NCH2)C6H4}R2SnCl] [R = Me (2a), Ph (3a)] were prepared by treating SnCl4 or R2SnCl2 with [Li{2-(Me2NCH2)C6H4}]. Halide-exchange reactions between the organotin(IV) chlorides and the appropriate potassium halides gave [{2-(Me2NCH2)C6H4}2SnX2] [X = F (1b), I (1d)], [{2-(Me2NCH2)C6H4}Me2SnX] [X = F (2b), Br (2c), I (2d)] and [{2-(Me2NCH2)C6H4}Ph2SnX] [X = F (3b), I (3d)]. Their solution behaviour was investigated by multinuclear (1H, 13C, 19F and 119Sn) NMR spectroscopy, including variable-temperature studies. Single-crystal X-ray diffraction analyses revealed that the strong intramolecular coordination of the nitrogen atom from the pendant CH2NMe2 group to tin induces chirality. The influence of the identity and the number of the halogen atoms and the organic substituents at tin is discussed in relation with the hydrogen-bonding network, which results in different supramolecular architectures in the crystal. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)