Publisher Summary This is one of two articles in this volume that is concerned with the borane-carborane structural pattern. In the other, Williams has shown how the pattern reflects the coordination number preferences of the various atoms involved. The purpose of the present article is to note some bonding implications of the pattern, and to show its relevance to a wide range of other compounds, including metal clusters, metal-hydrocarbon 7∼ complexes, and various neutral or charged hydrocarbons. Boranes and carboranes may be regarded as cluster compounds in the sense defined by Cotton; they contain a finite group or skeleton of atoms held together entirely, mainly, or at least to a significant extent by bonding directly between those atoms, even though some other atoms may be associated intimately with the cluster. Examples of their structural pattern, however, can be found far beyond the confines of what is normally regarded as cluster chemistry, so this survey includes many systems not commonly referred to as clusters.

Structural and Bonding Patterns in Cluster Chemistry

Publisher Summary Tin (Sn) compounds are well-recognized both in basic research and in industrial applications. Tin NMR spectroscopy includes three magnetically active tin isotopes namely, 115Sn, 117Sn , and l19Sn. However, most tin NMR parameters refer to the 119Sn nucleus owing to its properties such as abundance, magnetic moment, and NMR frequency. This chapter describes: (1) the compilation and updation of 119Sn chemical shifts (δ 119Sn) from studies on organotin compound and inorganic tin compounds, (2) indirect nuclear spin-spin couplings, (3) relaxation mechanisms concerning the 119Sn nucleus, and (4) experimental details for 1I9Sn-NMR measurements. It is observed that with modem equipment there are, in principle, no serious experimental difficulties in observing 119Sn resonances either directly or by heteronuclear double resonance. δ 119Sn data, available for all kinds of tin compounds, significantly allows using this parameter in an empirical way in order to find models for the qualitative interpretation of δ 119Sn. This also applies to couplings involving the l19Sn nucleus, which serve as a sensitive tool in the discussion of structure and bonding. All 119Sn-NMR parameters of tin compounds largely concern measurements in the liquid state.

119Sn-NMR Parameters

Boraneamines tend to have close N−Hδ+···δ-H−B contacts as a result of the intermolecular interaction of the NH proton with the BH bond by a novel type of hydrogen bond (the dihydrogen bond) A CSD structural search provides characteristic metric data for the interaction:  the H···H distance is in the range 17−22 A, and the N−H···H group tends to be linear while B−H···H tends to be bent The reported X-ray structure of BH3NH3 seemed to provide a singular exception in having bent N−H···H and linear B−H···H Our neutron diffraction structure of BH3NH3 now shows that the B and N atoms must be reversed from the assignment previously published With the correct assignment we find the expected bent B−H···H and linear N−H···H arrangement in the closest intermolecular N−H···H−B interaction (dHH = 202 A)

Study of the N−H···H−B Dihydrogen Bond Including the Crystal Structure of BH3NH3 by Neutron Diffraction

For a long time, Zintl ions of Group 14 and 15 elements were considered to be remarkable species domiciled in solid-state chemistry that have unexpected stoichiometries and fascinating structures, but were of limited relevance The revival of Zintl ions was heralded by the observation that these species, preformed in solid-state Zintl phases, can be extracted from the lattice of the solids and dissolved in appropriate solvents, and thus become available as reactants and building blocks in solution chemistry The recent upsurge of research activity in this fast-growing field has now provided a rich plethora of new compounds, for example by substitution of these Zintl ions with organic groups and organometallic fragments, by oxidative coupling reactions leading to dimers, oligomers, or polymers, or by the inclusion of metal atoms under formation of endohedral cluster species and intermetalloid compounds; some of these species have good prospects in applications in materials science This Review presents the enormous progress that has been made in Zintl ion chemistry with an emphasis on syntheses, properties, structures, and theoretical treatments

Zintl ions, cage compounds, and intermetalloid clusters of Group 14 and Group 15 elements.

We developed different strategies toward the synthesis of colloidal nanocrystals stabilized with molecular metal chalcogenide complexes (MCCs). Negatively charged MCCs, such as SnS44−, Sn2S64−, SnTe44−, AsS33−, MoS42−, can quantitatively replace the organic ligands at the nanocrystal surface and stabilize nanocrystal solutions in different polar media. We showed that all-inorganic nanocrystals composed of metals, semiconductors, or magnetic materials and capped with various MCC ligands can be synthesized using convenient and inexpensive chemicals and environmentally benign solvents such as water, formamide, or dimethylsulfoxide. The development of mild synthetic routes was found to be crucial for the design of highly luminescent all-inorganic nanocrystals, such as CdSe/ZnS and PbS capped with Sn2S64− MCCs, respectively. We also prepared conductive and luminescent layer-by-layer assemblies from inorganically capped colloidal nanocrystals and polyelectrolytes. In close-packed films of 5-nm Au nanocrystals s...

Expanding the chemical versatility of colloidal nanocrystals capped with molecular metal chalcogenide ligands.

Nature of naked-metal-cluster polyanions in solution. Evidence for (Sn9-xPbx)4-(x = 0-9) and tin-antimony clusters

Multinuclear NMR characterization of anionic clusters of the main-group elements germanium, tin, antimony, thallium, lead, and bismuth in nonaqueous solution

Naked-metal clusters in solution. 4. Indications of the variety of cluster species obtainable by extraction of Zintl phases: Sn42-, TlSn85-, Sn9-xGex4- (x = 0-9), and SnTe44-

Synthesis and crystal and molecular structure of trimethylammonium 7,8-dimercapto-7,8-dicarbaundecaborate(10) and trimethylammonium anti-7,7':8,8'-bis(dithio)bis(7,8-dicarbaundecaborate(10))

R. W. Rudolph

Papers

Nature of naked-metal-cluster polyanions in solution. Evidence for (Sn9-xPbx)4-(x = 0-9) and tin-antimony clusters

Multinuclear NMR characterization of anionic clusters of the main-group elements germanium, tin, antimony, thallium, lead, and bismuth in nonaqueous solution

Naked-metal clusters in solution. 4. Indications of the variety of cluster species obtainable by extraction of Zintl phases: Sn42-, TlSn85-, Sn9-xGex4- (x = 0-9), and SnTe44-

Synthesis and crystal and molecular structure of trimethylammonium 7,8-dimercapto-7,8-dicarbaundecaborate(10) and trimethylammonium anti-7,7':8,8'-bis(dithio)bis(7,8-dicarbaundecaborate(10))

Transition-metal insertion into naked metal cluster polyanions