Debye units

The debye unit is named in honor of Peter Debye a Dutch scientist who did im portant work in many areas of chemistry and physics and was awarded the Nobel Prize in chemistry in 1936... 

Debye unit (D) (Section 1 5) Unit customanly used for mea sunng dipole moments... 

Dipole moment (Section 1 5) Product of the attractive force between two opposite charges and the distance between them Dipole moment has the symbol p- and is measured in Debye units (D)... 

To convert debye units D into coulomb-meters, multiply by 3.33564 X 10... 

Figure 4 shows the measured angle of 105° between the hydrogens and the direction of the dipole moment. The measured dipole moment of water is 1.844 debye (a debye unit is 3.336 x 10 ° C m). The dipole moment of water is responsible for its distinctive properties in the Hquid state. The O—H bond length within the H2O molecule is 0.96 x 10 ° m. Dipole—dipole interaction between two water molecules forms a hydrogen bond, which is electrostatic in nature. The lower part of Figure 4 (not to the same scale) shows the measured H-bond distance of 2.76 x 10 ° m or 0.276 nm. 

The symbols 5+ and 5- indicate polarity of the two ends or poles of the electrically neutral molecule. Such a polar molecule constitutes a permanent dipole, i.e., two equal and opposite charges (e) separated by a distance (d) in space. A quantitative measure of the polarity of a molecule is the dipole moment (p in Debye units), which is defined as the product of the charge (e in electrostatic units) and the distance (d in cm). 

Dipole Moment. In vapor phase 3.54 debye units (Ref 9)... 

Values of the bond moments (in debye units) for the eight bonds shown in Figure 1-2 are given in Table 1-2. In Figure 1-3 the large circles represent... 

It should be borne in mind, however, that enzyme proteins, like other proteins, are dipolar ionic structures surrounded by an intense electrostatic field. Horse carboxyhemoglobin, for example, has a dipole moment of 480 Debye units (molecular weight, 67,000). Compared with amino acids, sugars have a rather low dipole moment, due mainly to a considerable measure of mutual cancellation of the constituent link moments resulting from their disposition in space (glycine = 15, a- and... 

The difference from the hydrocarbons is that the oxocarbenium ion resulting from the addition of R+ to the monomer becomes solvated by the strong dipoles of the monomer (for EVE ji = 1.14 Debye units (Taskinen et al. 1978)). 

The dipole moment is a fundamental property of a molecule (or any dipole unit) in which two opposite charges are separated by a distance . This entity is commonly measured in debye units (symbolized by D), equal to 3.33564 X 10 coulomb-meters, in SI units). Since the net dipole moment of a molecule is equal to the vectorial sum of the individual bond moments, the dipole moment provides valuable information on the structure and electrical properties of that molecule. The dipole moment can be determined by use of the Debye equation for total polarization. Examples of dipole moments (in the gas phase) are water (1.854 D), ammonia (1.471 D), nitromethane (3.46 D), imidazole (3.8 D), toluene (0.375 D), and pyrimidine (2.334 D). Even symmetrical molecules will have a small, but measurable dipole moment, due to centrifugal distortion effects. Methane " for example, has a value of about 5.4 X 10 D. 

A (iipoie moment results wtier molecule has a permanent urc-i . en elect ton density, Individua) Gttarge separations in bonds cannot be measured, only the sum of ati individual bond moments. A dipole moment is eKpresscJ in debye units (D). 

Water can interact with ionic or polar substances and may destroy their crystal lattices. Since the resulting hydrated ions are more stable than the crystal lattice, solvation results. Water has a very high dielectric constant (80 Debye units [D] versus 21 D for acetone), which counteracts the electrostatic attraction of ions, thus favoring further hydration. The dielectric constant of a medium can be defined as a dimensionless ratio of forces the force acting between two charges in a vacuum and the force between the same two charges in the medium or solvent. According to Coulomb s law. 

Another member of this series is bis(cyclopentadienylnickel carbonyl), (CsHaNiCO it is dimeric, diamagnetic, and must, therefore, contain a nickel-nickel bond (79). The dipole moment, quoted (79) as 0 0.38 Debye unit, indicates that the molecule must be very nearly centro-sym-metric in benzene. The infrared spectrum, however, shows two carbonyl stretching frequencies in the solid state and in solution, but the vapor at 100°C shows only one band (173, 199). The wave-numbers are shown in Table IV. 

I he very small quantify is eonveneil into a more easily quotable one by dividing the result by 3.33564 x 10" ll. giving 1.826 D lor the dipole moment in Debye units. The Debye is a non-S.l unit related to the S.l. unit C m by the relation ... 

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