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Frank Ruthe

Bio: Frank Ruthe is an academic researcher from Braunschweig University of Technology. The author has contributed to research in topics: Ylide & Cycloaddition. The author has an hindex of 18, co-authored 47 publications receiving 739 citations.

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TL;DR: In this paper, the authors reviewed the properties of Se and I van der Waals distances to strong covalent bonds with the help of recent structural determinations of compounds exhibiting SeI distances from 384 to 244 pm, with emphasis on less clearcut cases.

58 citations

Journal ArticleDOI
TL;DR: In this paper, an X-ray crystallographic study of adducts of trialkylphosphine selenides with > 1 equivalent of diiodine was performed.

36 citations

Journal ArticleDOI
TL;DR: In this paper, the authors compare IOD-IOD Wechselwirkung with Hydroxyphosphoniumionen in Losung wird dadurch erschwert, das beide Arten von Kationen ahnliche 31P-NMR-Verschiebungen aufweisen und beide kationen wechsel wirkungen mit ihren Anionen und rasche Austauschgleichgewichte eingehen.
Abstract: Triisopropylphosphan (1) ergibt mit Iod i-Pr3PI+I– (2), dessen Iod-Iod Wechselwirkung aufweisende Ionenpaare als Dichlormethan-Solvat kristallisieren. Mit weiterem Iod entsteht i-Pr3PI+I3– (3), aus 2 und AgSbF6 erhalt man i-Pr3PI+SbF6– (6). In Gegenwart von Luftfeuchtigkeit entstehen rasch Triisopropylhydroxyphosphoniumsalze, von denen i-Pr3POH+I– (4) P–O–H…I-Wasserstoffbrucken aufweist und (i-Pr3PO)2H+I3– (5) P=O…H…O=P-verbruckte Kationen enthalt. Die Unterscheidung zwischen Iodphosphoniumionen und Hydroxyphosphoniumionen in Losung wird dadurch erschwert, das beide Arten von Kationen ahnliche 31P-NMR-Verschiebungen aufweisen und das beide Kationen Wechselwirkungen mit ihren Anionen und rasche Austauschgleichgewichte eingehen: I+-Transferreaktionen an 1 und H+-Transferreaktionen an i-Pr3P=O (7). Oxidation of Triisopropylphosphane with Iodine: The Role of Dry or Moist Solvent i-Pr3P (1) and iodine give i-Pr3PI2 (2). In crystals obtained from CH2Cl2 solution, ion pairs [i-Pr3PI+I–] of 2 exhibiting I…I interactions are linked by CH2Cl2 molecules. With a second equivalent of iodine, i-Pr3PI+ I3– (3) is formed; the reaction of 2 with AgSbF6 provides i-Pr3PI+SbF6– (6). The presence of moisture and air leads to the formation of i-Pr3POH+ salts. Solid i-Pr3POH+I– (4) exhibits P–O–H…I cation-anion contacts, solid (i-Pr3PO)2H+I3– (5) contains a centrosymmetric P=O…H…O=P-bridged cation. Distinguishing i-Pr3PI+ salts 2, 3 from hydrolysis products 4, 5 by 31P-NMR in reaction mixtures is not trivial, because both kinds of cations exihibit similar 31P-NMR shifts and both participate in interactions with their anions, and in equilibria with uncharged donors: rapid I+ transfer reactions and I…I soft-soft interactions involving 1, and rapid H+ transfer reactions and hydrogen bonds involving i-Pr3P=O (7).

35 citations


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Journal ArticleDOI
TL;DR: The key unifying feature of almost all molecules discussed in this review is that they are generally stabilized by the use of bulky substituents which block associative or various decomposition pathways.
Abstract: This review is essentially an update of one entitled “πBonding and The Lone Pair Effect in Multiple Bonds Between Heavier Main Group Elements” which was published more than 10 years ago in this journal.1 The coverage of that survey was focused on the synthesis, structure, and bonding of stable compounds2 of heavier main group elements that correspond to the skeletal drawings reproduced in Tables 1 and 2. A row of numbers is listed at the bottom of each column in these tables. This refers to the number of stable complexes from each class that are currently known. The numbers in parentheses refer to the number of stable species that were known at the time of the previous review. Clearly, many of the compound classes listed have undergone considerable expansion although some remain stubbornly rare. The most significant developments for each class will be discussed in detail under the respective sections. As will be seen, there are also a limited number of multiple bonded heavier main group species that do not fit neatly in the classifications in Tables 1 and 2. However, to keep the review to a manageable length, the limits and exclusions, which parallel those used earlier, are summarized as follows: (i) discussion is mainly confined to compounds where experimental data on stable, isolated species have been obtained, (ii) stable compounds having multiple bonding between heavier main group elements and transition metals are not generally discussed, (iii) compounds in which a multiple bonded heavier main group element is incorporated within a ring are generally not covered, and (iv) hypervalent main group compounds that may incorporate faux multiple bonding are generally excluded. Such compounds are distinguished from those in Tables 1 and 2 in that they apparently require the use of more than four valence bonding orbitals at one or more of the bonded atoms. The remainder of this review is organized in a similar manner to that of the previous one wherein the compounds to be discussed are classified according to those summarized in Tables 1 and 2. The key unifying feature of almost all molecules discussed in this review is that they are generally stabilized by the use of bulky substituents which block associative or various decomposition pathways.3 Since the previous review was published in 1999, several review articles that cover parts of the subject matter have appeared.4

865 citations

Journal ArticleDOI
TL;DR: The subject of hypervalency has not attracted much attention and is the focus of this review of selenium chemistry, which has now become a well-established field of research.
Abstract: In 1836 the first organoselenium compound, diethyl selenide, was prepared by Löwig,1 and it was isolated in the pure form in 1869.2 Early selenium chemistry involved the synthesis of simple aliphatic compounds such as selenols (RSeH), selenides (RSeR), and diselenides (RSeSeR); however, because of their malodorous nature, these compounds were difficult to handle. This, combined with the instability of certain derivatives and difficulties in purification, meant that selenium chemistry was slow to develop. By the 1950s, the number of known selenium compounds had increased significantly, but it was not until the 1970s, when several new reactions leading to novel compounds with unusual properties were discovered, that selenium chemistry began to attract more general interest.3-9 Aryl-substituted compounds were synthesized that were found to be less volatile and more pleasant to handle than the earlier aliphatic compounds. Compounds containing selenium in high oxidation states are relatively easy to manipulate using modern techniques.4c Organoselenium chemistry has now become a well-established field of research, and recent advances have been brought about by the potential technical applications of selenium compounds. Today selenium compounds find application in many areas including organic synthesis,4 biochemistry,5 xerography,6 the synthesis of conducting materials7 and semiconductors,8 and ligand chemistry.4c,9 Many of these aspects of selenium chemistry are wellcovered elsewhere in the literature; however, the subject of hypervalency has not attracted much attention and is the focus of this review.10

439 citations