Dipole Moments, Conductance, and Polarography

A method of evaluating dipole moments has been devised which takes into account d -p contributions. The decrease in dipole moment which occurs when ortho methyl groups are present in triarylphosphines, e.g. (214), indicates 

The endo PS bond moment in (221 X = Cl) was estimated to be 0.58 D and directed from sulphur to phosphorus. The dipole moments of fourteen enol 

The polarographic reduction of triphenylphosphine oxide and trioctyl-phosphine oxide at low concentration in nitroethane has been studied. The estimation of phosphate insecticides by polarography has been reported, and the rearrangement of a-hydroxyphosphinates has been followed by conductance.  

Dipole moments (ft) were calculated for most of the compounds studied by microwave spectroscopy (see Section 4). The P —N bond moment has been estimated to be 0.26 D from the dipole moments of trisdimethyl-aminophosphine (ft = 1.32 D) and derivatives of (174). However, it is difficult to accept that the P —N bond moment of the oxide of (174) is 

Comparisons of measured and calculated dipole moments of formyl-, acyl-, and aroyl-methylenetriphenylphosphoranes (179) are discussed in relation to their conformations and charge delocalizations. The data support a predominance of the ci forms (179) in benzene solution. Similar comparisons for the ketophosphoryl compounds (180) indicated a predominance (ca. 90%) of the transoid conformation, as shown in (180).  

Similar studies have been made on the conformations of alkyl methyl-phenylphosphinates (131) and on the stereochemistry of the cyclic phosphites (60). - The moment for the C sp )—P bond is 1.07 D, as estimated from the dipole moments of diethyl styrylphosphonate (181) and some of its derivatives.  

The conductance of quaternary phosphonium salts and diphenyl-phosphinic acid and its derivatives has been measured, and an indirect polarographic determination of mixed phosphates and arsenates is reported.  

---