P-H stretching

It is immiscible in water but is very soluble in common organic solvents, e.g., ethanol, ether, tetrahydrofuran, and benzene. The gaseous infrared spectrum2 exhibits a strong P—H stretch at 2292 cm.-1. Other infrared bands occur at 2920, 1085, 930, 838, 820, and 670 cm.-1. The 31P n.m.r. spectrum shows the expected triplet centered at 131 p.p.m., with a /P H of 193 Hz.f The n.m.r. spectrum consists of a doublet centered at 3.3 p.p.m., with /p H = 194 Hz. Each half of this doublet is further split into a triplet as a result of the coupling of the phosphorus protons with the methylene protons (/ 6 Hz.). The methylene protons exhibit a complex pattern centered at 2.22 p.p.m. ... 

Family General Formula >P=0 Stretch >P-H Stretch >P—O—C< Stretch -OH Stretch Notes... 

Infrared spectroscopy can also be of diagnostic use for the identification of organophosphorus compounds and comprehensive data is available from several sources.18 Diagnostic absorptions include the P—H stretch, which typically occurs in the region 2460-2450 cm-1, the P=0 stretch at 1320-1200 cm-1 and the P=N at 1440-1120 cm-1. Other useful absorptions include the P—O—(C) stretch at 870-730 cm-1 and the P—O—P stretch at 800-650 cm-1 found in phosphate esters. 

Phenylphosphino)ethyl]diphenylphosphine crystallizes from pentane as white needles melting around room temperature (ca. 30°) and boiling at 201-202°/0.08 torr (literaturei 210-215°/ torr). The P—H stretching frequency in the infrared spectrum occurs at 2286 cm-i. The nmr spectrum (CDCI3 solution, TMS internal standard) consists of a multiplet at t2.78 (phenyl protons), broad multiplets at t7.9 and t8.2 (methylene protons), and a doublet of triplets at t6.4 (PH proton triplet separation ca. 6 Hz). The 3ip nmr spectrum (CDCI3 solution) consists of a broad resonance at... 

What accounts for the very different behavior in PH3 First, the P—H stretches are already rather intense, even in the isolated monomer. This difference can be traced to the... 

Band Assignments and Structure Elucidation.— The conjugated A -phospholens can be distinguished from A -phospholens by the low frequency ca. 2225 cm ) of their P—H stretching vibrations. The i.r. and Raman spectra of the chloride (122)... 

PH2D, PHD2. The frequency of the P-H stretching vibration in PHD2, v = 2323.81 cm" was determined by Fourier transform spectroscopy and used together with the overtone 2v = 4563.26 cm" to derive co(P-H) = 2408.17 cm" treating the P-H unit as a diatomic molecule [12]. - For the fundamental frequencies of the species in solid phases, see p. 192. 

Do = 345 kJ/mol for the P-H bond in PHD2 was derived from the experimental P-H stretching frequency by treating the P-H unit as a diatomic molecule [12]. 

The first overtone of P-H stretching was found at 5288 cm (1891 nm) in a number of organo-phosphorus compounds. It is slightly more intense than the S-H absorption, having a molar absorptivity of about 0.24 1/mol-cm. It is described as being more diffuse and less sharp, however. The POH group is observed in phosphorothioic acids. The absorption is significantly shifted relative to the hydroxyl in alcohols, as it is in mid-infrared. The near-infrared (NIR) peak appears at about 5241 cm (1908 nm). 

Phosphorus. - The near-IR spectrum of PH3 has been reported in the P-H stretch overtone region." The IR spectrum of CH2=CHPH2 contains bands due to both syn and gauche conformers - assignments were backed by DFT calculations." Variable-temperature IR studies on C1CH2P(S)F2 in liquid krypton and xenon solutions show that the trans form is more stable than the gauche. ... 

In the IR spectra of the complexes, containing primary and secondary phosphine ligands the bands of P-H stretching modes are observed, besides the bands of Cp ring. The v(P-H) frequencies (2305 cm ) in the complexes are 50 cm higher than those for free phosphines (2253 cm ). The increase of frequencies is a consequence of the formation of the P — Ln bond. 

The IR spectrum erf" Zr-COOH-H looks like that of Zr(03FCH2CH2COOH)2 with a superimposed P-H stretch at 2473 cm"l. The 1703 emr C=0 stretch of Zr COOH-H suggests a similarity between these carboxylic add groups and those found both in Zr-COOH-OH and Zr(03PCH2CH2C0aT)2. The CP MAS NMR... 

II. P—H stretch. 2505-2222 cm, strong and sharp in IR and Raman Example of use At one time it was thought that compounds P(OH)(OR)2 existed, until it was found from the IR spectrum that they have a P—H bond. They are really H P(=0)(OR)2. 

A. For PH2, the bond angle is close to 90° (about 94°), and with the presence of the heavy central P atom coupling between the antisymmetric and symmetric P—H stretching bands is greatiy reduced and the bands are not resolved. 

Phosphorous compounds are examined in much the same fashion as the silicon systems. A general introduction (I) is followed by discussions of the P—H stretch (II), PH, PH2 and P-CH3 systems (III, A, B, C). The P=0 stretch (IV) is discussed in some detail. It can provide considerable information about the environment of the P=0 group. This section closes with an examination of P—O—C stretches (V) which can be correlated with both aliphatic and aromatic substituents. 

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