Bond multiple

Monomer (Section 6 21) The simplest stable molecule from which a particular polymer may be prepared Monosaccharide (Section 25 1) A carbohydrate that cannot be hydrolyzed further to yield a simpler carbohydrate Monosubstituted alkene (Section 5 6) An alkene of the type RCH=CH2 in which there is only one carbon directly bonded to the carbons of the double bond Multiplicity (Section 13 7) The number of peaks into which a signal IS split in nuclear magnetic resonance spectroscopy Signals are described as singlets doublets triplets and so on according to the number of peaks into which they are split... 

Step 2. Only one bond is broken in this step and no bonds are formed. (The movement of a pair of unshared electrons into the C-C bond, forming a double bond, is not designated by any symbol. In this system, bond multiplicity changes are understood without being specified.) Thus the symbol is D. The broken bond is between a core atom (C) and a nucleofuge (Cl), so the designation is D. ... 

When factors work in the same direction (effective nuclear charge and bond polarity in the case of C — N < C — C), we can make confident predictions. When factors work in the opposite direction ( value and bond multiplicity in the case of H — C < C 1 O), we can explain the observed values but could not predict them. 

That way, the Distributed Electrostatic Moments based on the ELF Partition (DE-MEP) allows computing of local moments located at non-atomic centres such as lone pairs, a bonds and n systems. Local dipole contributions have been shown to be useful to rationalize inductive polarization effects and typical hydrogen bond interactions. Moreover, bond quadrupole polarization moments being related to a n character enable to discuss bond multiplicities, and to sort families of molecules according to their bond order. 

Figure 6-3. Correlation between the quadrupolar polarization ( M2 ) of CO bonds in selected molecule and of the bond multiplicity...

Certain general trends in M-0 bond distances can be correlated with bond multiplicity and the degree of oxygen-to-metal TT-bonding. A comparison of M-0 bond distances for structurally related compounds having a M, (p3-X) 2 (p2-X) Xx 0 unit is given in Table II. For M = Mo and W in closely related compounds, differences in M-L distance are negligible. 

Conjugation The process of covalently bonding (multiple) copies of a hapten to a carrier protein, usually by means of a linker to distance the hapten from the surface of the carrier protein by a chain of about six atoms. 

A general type of chemical reaction between two compounds, A and B, such that there is a net reduction in bond multiplicity (e.g., addition of a compound across a carbon-carbon double bond such that the product has lost this 77-bond). An example is the hydration of a double bond, such as that observed in the conversion of fumarate to malate by fumarase. Addition reactions can also occur with strained ring structures that, in some respects, resemble double bonds (e.g., cyclopropyl derivatives or certain epoxides). A special case of a hydro-alkenyl addition is the conversion of 2,3-oxidosqualene to dammara-dienol or in the conversion of squalene to lanosterol. Reactions in which new moieties are linked to adjacent atoms (as is the case in the hydration of fumarate) are often referred to as 1,2-addition reactions. If the atoms that contain newly linked moieties are not adjacent (as is often the case with conjugated reactants), then the reaction is often referred to as a l,n-addition reaction in which n is the numbered atom distant from 1 (e.g., 1,4-addition reaction). In general, addition reactions can take place via electrophilic addition, nucleophilic addition, free-radical addition, or via simultaneous or pericycUc addition. 

D. Where there is no conflict with other guidelines, triple bonds are senior to double bonds, which in turn are senior to single bonds multiple bonds should be assigned the lowest possible locants. Thus, the polymer from 1,3-butanediene polymerized in the 1,4- mode is usually indicated as-(—C—C=C—C — )-but is named as though it were-( - C=C - C - C - )-and named poly(l-butene-1,4-diyl) with the appropriate cis- or tra i-designation. Polyisoprene, typically drawn as-(—CH2 —C(CH3)=CH—CH2 —) —is frequently named poly(2-methyl-1,3-butadiene) but is named as though its structure were-(C(CH3)=CH—CH2—CH2 — ) —with the namepoly(l-methyl-1 -butene-1,4-diyl). 

In the other method, the ending -ane is changed to -ene or -yne to indicate the presence of a double or triple bond. This is used for alkanes and mono- and polycyclic alkane parent hydrides. In alkanes and cycloalkanes, the change of the -ane ending to -ene or -yne indicates the presence of one double or triple bond. Multiplicative prefixes di-, tri-, tetra-, etc. are used to signal the multiplicity of unsaturated bonds. Locants placed immediately in front of the endings -ene and -yne are used as needed. 

Problem 12.12 How do the following factors affect absorption frequencies Use data in Tables 12-1 and 12-2. (a) For C—H stretch, the hybrid orbitals used by C. b) Bond strength i.e., change in bond multiplicity, (c) Change in mass of one of the bonded atoms e.g., O—H versus O—D. (d) Stretching versus bending, (e) H-bonding of OH. <... 

Indicate the position of nitrogen in Mendeleev s periodic table of the elements, the electron configuration and the size of its atom, and the oxidation states it exhibits. Write the electron configuration of a nitrogen molecule. What is the bond multiplicity in it ... 

Any double or triple bond is often referred to as a multiple covalent bond. Multiple bonds higher than these, such as the quadruple covalent bond, are not commonly observed. 

Bond Multiplicity One of the most obvious factors affecting the distance between two atoms is the bond... 

The BRC concept [99] allows the analysis of the elementary actions of chemical transformation at the level of active complexes, in which electron density is redistributed in accordance with bond multiplicity change. Generally, this is expressed by the rule of multiplicity alternating change ... 

In both diagrams the change of bond multiplicity in the catalysis act meets the rule 1, which reflects the condition of BRC conductivity for electron. 

Independent of the conformation, the bond multiplicity must be only two. If the shorter distances are a requirement for optimum overlap for ti-MOs, these requirements must also exist in multiple bonds involving a- and 7t-bonds. The 7t-bonds, however, are forced by the overwhelming a-bonds to be at non-optimal overlapping distances. While there are many factors that contribute to the observed bond lengths in a binuclear transition metal complex, shorter distances would be mandated by n- and 8-MOs for optimum overlap. The 7t-alone-bonding proposed for Fe2(CO)6 allows 71-bonds to attain their natural shorter distances. The overlap of... 

It is of vital interest for a wider applicability of CTCB to examine how these two mechanisms can be accommodated in OCT. In Section 3, we shall argue that the mutual decoupling status of several subsets of basis functions, manifesting itself by the absence of any external communications (bond orders) in the whole system, calls for the separate unit normalization of its input probabilities since such fragments constitute the mutually nonbonded (closed) building blocks of the molecular electronic structure. It will be demonstrated, using simple hydrides as an illustrative example, that the fulfillment of this requirement dramatically improves the agreement with the accepted chemical intuition and the alternative bond multiplicity concepts formulated in the MO theory. 

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