Hybridized C-B compounds

Since the a-C atoms in C-nitro compounds are sp3 hybridized, whereas these atoms in nitronates are sp2 hybridized, the signals for both the a-C atom and the protons bonded to this atom are shifted in nitronates to lower field. However, all of the above mentioned signals in the NMR spectra of nitronates RR,C=N(0)0X do appear at higher field than the corresponding signals for analogous oximino derivatives RR,C=N-0- due to the contribution of resonance structures A and B shown in Chart 3.6. 

The most important substrates for substitutions of this type are alkenyl and aryl triflates, bromides, or iodides (Sections 16.1-16.4). The most important organometallic compounds to be introduced into the substrates contain Cu, Mg, B, Zn or Sn. The metal-bound C atom can be sp2-, sp2-, or. sp-hybridized in these compounds, and each of these species, in principle, is capable of reacting with unsaturated substrates. Organocopper compounds often (Section 16.1, 16.2), but not always substitute without the need for a catalyst (Section 16.4.5). Grignard compounds substitute in the presence of catalytic amounts of Ni complexes (Section 16.3), while organoboron (Section 16.4.2), organozinc (Section 16.4.3) and organotin (Section 16.4.4) compounds are typically reacted in the presence of Pd complexes (usually Pd(PPhj)4). 

An sp hybridized C—Cl bond is more polar than an sp hybridized C-CI bond, (a) Explain why this phenomenon arises, (b) Rank the following compounds in order of increasing boiling point. 

This section is primarily concerned with the geometrical characteristics of the diazo group obtained by X-ray diffraction studies of benzenediazonium compounds (1), a-diazoketones (resonance hybrids 2a,b,c) and diazoalkanes (3a,b). The section concludes with some geometrical details for the analogous azido group (4a,b). There are 50 crystal-... 

A molecule containing one 7t-bond as part of a C=C unit is called an alkene (see Chapter 5, Section 5.1). When a molecrde contains two 7i-bonds in two C=C units, it is called a diene. There are three fundamental structmal variations for a diene (a) those where the C=C units are separated by sp hybridized atoms, (b) those where the C=C units are connected together to form a C=C-C=C unit, and (c) those that contain two 7i-bonds that share an sp hybridized atom. Compounds (a) are called nonconjugated dienes using the standard nomenclature rules for alkenes introduced in Chapter 5, an example is 1,5-hexadiene (1). Compounds (b) are called conjugated dienes, illustrated by 1,3-hexadiene (2). Note that 2 contains an E double bond (see Chapter 9, Section 9.4.3) and the name must reflect this structural feature. Therefore, 2 is l,3 -hexadiene. 

Compare, for example, the IR spectra of 5-methyl-2-hexanone (A) and ethyl propanoate (B) in Figure 13.9. The IR spectra look similar in their functional group regions because both compounds contain a carbonyl group (C=0) and several sp hybridized C-H bonds. Since A and B are different compounds, however, their fingerprint regions look very different. 

Borazine, B3N3Hft, a compound that has been called inorganic benzene because of its similar hexagonal structure (but with alternating B and N atoms in place of C atoms), is the basis of a large class of boron—nitrogen compounds. Write its Lewis structure and predict the composition of the hybrid orbitals used by each B and N atom. 

Given that carbon has a valence of four in nearly all its compounds and can form chains and rings of G atoms, (a) draw any two of the three possible structures for C3H4 (b) determine all bond angles in each structure (c) determine the hybridization of each carbon atom in the two structures ... 

Diborane reacts with ammonia to form an ionic compound (there are no other products). The cation and anion each contain one boron atom, (a) Predict the identity and formula of each ion. (b) Give the hybridization of each boron atom, (c) Identify the type of reaction that has occurred (redox, Lewis acid-base, or Bronsted acid-base). 

X 14.111 (a) Examine the structures of diborane, B2H6, and AI2CI6(g), which can be found on the Web site for this book. Compare the bonding in these two je compounds. How are they similar (b) What are the differences, if any, in the types of bonds formed (c) What is the hybridization of the Group 13/III element (d) Are the molecules planar If not, describe their shapes. 

The monomer of the conducting polymer polyaniline is the compound aniline (aminobenzene). (a) Draw the structural formula of the aniline monomer. What is the hybridization of the N atom in (b) aniline (c) polyaniline (d) Indicate the locations of lone pairs, if any, in polyaniline, (e) Do the N atoms help to carry the current Explain your reasoning. See Box 19.1. 

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