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The potential involvement of polysulfide radical anions Sn•− is a recurring theme in discussions of the basic and applied chemistry of elemental sulfur. However, while the spectroscopic features for n = 2 and 3 are well-established, information on the structures and optical characteristics of the larger congeners (n = 4–8) is sparse. To aid identification of these ephemeral species we have performed PCM-corrected DFT calculations to establish the preferred geometries for Sn•− (n = 4–8) in the polar media in which they are typically generated. TD-DFT calculations were then used to determine the number, nature and energies of the electronic excitations possible for these species. Numerical reliability of the approach was tested by comparison of the predicted and experimental excitation energies found for S2•− and S3•−. The low-energy (near-IR) transitions found for the two acyclic isomers of S4•− (C2h and C2v symmetry) and for S5•− (Cs symmetry) can be understood by extension of the simple HMO π-only chain model that serves for S2•− and S3•−. By contrast, the excitations predicted for the quasi-cyclic structures Sn•− (n = 6–8) are better described in terms of σ → σ* processes within a localized 2c-3e manifold.

Chalcogen-nitrogen chemistry involves the study of compounds that exhibit a linkage between nitrogen and sulfur, selenium or tellurium atoms. Such studies have both fundamental and practical importance. A Guide to Chalcogen-Nitrogen Chemistry examines the role of chalcogen-nitrogen compounds in areas ranging from solid-state inorganic chemistry to biochemistry. The discussion covers fundamental questions concerning the bonding in electron-rich systems, as well as potential practical applications of polymers and materials with novel magnetic or electrical properties. This book is the only account of this important topic to appear in the last twenty-five years, and coupled with its extensive literature coverage of very recent developments, this comprehensive guide is essential for anyone working in the field. The treatment is unique in providing a comparison of sulfur, selenium and tellurium systems, with an approach intended to emphasize general concepts that will be helpful to the non-specialist. Each chapter is designed to be self-contained, and there are extensive cross-references between chapters.

Chalcogen-nitrogen chemistry involves the study of compounds that exhibit a linkage between nitrogen and sulfur, selenium or tellurium atoms. Such studies have both fundamental and practical importance. A Guide to Chalcogen-Nitrogen Chemistry examines the role of chalcogen-nitrogen compounds in areas ranging from solid-state inorganic chemistry to biochemistry. The discussion covers fundamental questions concerning the bonding in electron-rich systems, as well as potential practical applications of polymers and materials with novel magnetic or electrical properties. This book is the only account of this important topic to appear in the last twenty-five years, and coupled with its extensive literature coverage of very recent developments, this comprehensive guide is essential for anyone working in the field. The treatment is unique in providing a comparison of sulfur, selenium and tellurium systems, with an approach intended to emphasize general concepts that will be helpful to the non-specialist. Each chapter is designed to be self-contained, and there are extensive cross-references between chapters.

X-ray structural investigations have shown that the products of the reaction of CuCl 2 · 2H 2 O and OP[NH-t-Bu] 3 are markedly dependent on solvent and temperature. The polymeric ionic complex [(t-BuNH 3 ) 2 (Cu 3 (OH)(H 2 O)Cl 7 )] ∞ ( 1 ), containing a trinuclear anionic repeating unit, is obtained from toluene at 80 °C, whereas the 2:1 adduct Cu(t-BuNH 2 ) 2 Cl 2 ( 4 ) is formed at 150 °C. By contrast, a neutral tetranuclear cluster Cu 4 [PO(NH-t-Bu) 3 ] 4 (µ 4 -O)Cl 6 ( 2 ) or the one-dimensional chain [Cu(Py) 2 Cl 2 ] ∞ ( 3 ) is produced when the reaction is carried out in hexane or pyridine, respectively, at 80 °C. The reaction of a mixture of CuCl and CuCl 2 · 2H 2 O (2:1 molar ratio) with OP[NH-t-Bu] 3 at 80 °C in toluene produces [t-BuNH 3 ] 5 [Cu 5 Cl 10 ] ( 5 ), in which the anion is a pentanuclear cluster with both terminal and bridging chloride ions. The removal of the chloride ions from the reaction mixture by the addition of AgNO 3 yields the 2:1 adduct Cu[OP(NH-t-Bu) 3 ] 2 (NO 3 ) 2 ( 6 ).Key words: copper halides, templation, P-N compounds, cluster complexes, one-dimensional framework

X-ray structural investigations have shown that the products of the reaction of CuCl^sub 2^-2H^sub 2^O and OP[NH-t-Bu]^sub 3^ are markedly dependent on solvent and temperature. The polymeric ionic complex [(t-BuNH^sub 3^)^sub 2^(Cu^sub 3^(OH)(H^sub 2^0)Cl^sub 7^)∞ (1), containing a trinuclear anionic repeating unit, is obtained from toluene at 80 °C, whereas the 2:1 adduct Cu(t-BuNH^sub 2^)^sub 2^Cl^sub 2^ (4) is formed at 150 °C. By contrast, a neutral tetranuclear cluster Cu^sub 4^[PO(NH-t-Bu)^sub 3^]^sub 4^(µ^sub 4^-O)Cl^sub 6^ (2) or the one-dimensional chain [Cu(Py)^sub 2^Cl^sub 2^]∞ (3) is produced when the reaction is carried out in hexane or pyridine, respectively, at 80 °C. The reaction of a mixture of CuCl and CuCl^sub 2^-2H^sub 2^0 (2:1 molar ratio) with OP[NH-t-Bu]^sub 3^ at 80 °C in toluene produces [t-BuNH^sub 3^]^sub 5^[Cu^sub 5^Cl^sub 10^] (5), in which the anion is a pentanuclear cluster with both terminal and bridging chloride ions. The removal of the chloride ions from the reaction mixture by the addition of AgNO^sub 3^ yields the 2:1 adduct Cu[OP(NH-t-Bu)^sub 3^]^sub 2^(N0^sub 3^)^sub 2^ (6). [PUBLICATION ABSTRACT]

The use of trichloroiminophosphoranes [Cl.sub.3]P=NR to control the concurrent release of the templating cation [[RN[H.sub.3]].sup.+] and chloride ligand via in situ P--N and P--Cl bond cleavage produced two new copper(II) chloride oligomers. The nature of the organic substituent R was a factor in determining the chain lengths. For n-propyltrichloroiminophosphorane, the hexanuclear cluster [[n-PrN[H.sub.3]].sub.2][[Cu.sub.6][Cl.sub.14]] (1) was obtained, while p-tolyltrichloroiminophosphorane generated the tetranuclear copper chloride salt [4-C[H.sub.3][C.sub.6][H.sub.4]N[H.sub.3]] [2-Cl-4-C[H.sub.3][C.sub.6][H.sub.3]N[H.sub.3]][[Cu.sub.4][Cl.sub.10]] (2). In both structures a two-dimensional framework displaying a herringbone arrangement is created by Cu--Cl secondary bonding interactions. The direct addition of the [[n-PrN[H.sub.3]].sup.+] cation to a Cu[Cl.sub.2] x 2[H.sub.2]O solution under the same reaction conditions produced [[n-PrN[H.sub.3]].sub.2][Cu[Cl.sub.4]].

The use of trichloroiminophosphoranes Cl^sub 3^P=NR to control the concurrent release of the templating cation [RNH^sub 3^]^sup +^ and chloride ligand via in situ P-N and P-Cl bond cleavage produced two new copper(II) chloride oligomers. The nature of the organic substituent R was a factor in determining the chain lengths. For n-propyltrichloroiminophosphorane, the hexanuclear cluster [n-PrNH^sub 3^]^sub 2^[Cu^sub 6^Cl^sub 14^] (1) was obtained, while p-tolyltrichloroiminophosphorane generated the tetranuclear copper chloride salt [4-CH^sub 3^C^sub 6^H^sub 4^NH^sub 3^][2-Cl-4-CH^sub 3^C^sub 6^H^sub 3^NH^sub 3^][Cu^sub 4^Cl^sub 10^] (2). In both structures a two-dimensional framework displaying a herringbone arrangement is created by Cu-Cl secondary bonding interactions. The direct addition of the [n-PrNH^sub 3^]^sup +^ cation to a CuCl^sub 2^.2H^sub 2^O solution under the same reaction conditions produced [n-PrNH^sub 3^]^sub 2^[CuCl^sub 4^]. [PUBLICATION ABSTRACT]

The imido group (NR) is a versatile ligand in main group chemistry. The high reactivity of multiply bonded (terminal) imido derivatives of p-block elements is used, for example, in the aza-Wittig reaction, allylic aminations, and in peptide synthesis. As a bridging ligand, the imido group provides a cornerstone for a wide variety of binary cluster structures. This review is primarily concerned with the synthesis, structures, reactions, and ligand behaviour of imido derivatives of the heavy chalcogens (selenium and tellurium) as exemplified by the tellurium diimide dimer t-BuNTe(µ-N-t-Bu) 2 TeN-t-Bu and the homoleptic trisimido-tellurite dianion [Te(N-t-Bu) 3 ] 2– . The synthesis and cluster structures of alkali metal and alkaline earth metal derivatives of heteroleptic imido-oxo anions of sulfur, e.g., [O x S(NR) 3 – x ] 2– (x = 1, 2) and [O 2 S(µ-NPh)SO 2 ] 2– , are also discussed.Key words: main group chemistry, imido ligand, chalcogens.