The crystal structure of [Pd(dppm) Br], (dppm = Ph,PCH,PPh2) shows that the palladium(1) atoms are directly metal-metal bonded and adopt an idealised square-planar stereochemistry.THE preparation of the complexes [Pd(dam)X], (dam = Ph,AsCH,AsPh,; X = C1, Br) and their establishment as compounds of palladium(1) was recently rep0rted.l By the action of dppm (Ph,PCH,PPh,) and the halogenocarbonyls Pd(C0)X we have now prepared similar complexes of the type [Pd(dppm)X], and the crystal structure of one o f these, [Pd(dppm)Br],, is reported here.Crystal data : C,,HMBr2P,Pd,, M = 1141, monoclinic, space group P2,/c; a = 13-661(4), b = 16.726(4), c = 21.442(6) A, = 106-00(4)" (h = 0.7107 A for Mo-K,); U = 4710 A3, 2 = 4, D, = 1-61 g ~m -~, p = 27-18 cm-l for Mo-K,.Crystals were obtained from a dichloromethane-hexane solution and the structure was solved by conventional heavy atom methods. Least-squares refinement with

No abstract

Electrospray mass spectrometry (ESMS) has been used to identify the mixture of components in three nonionic surfactants, nonylphenol ethoxylate (NPE), secondary alcohol ethoxylate (SAE), and primary alcohol ethoxylate (PAE). In each case singly protonated species are observed with the number of ethylene oxide units ranging from 4 to 16. Collisionally activated decomposition of protonated SAE leads to cleavage of the secondary carbon-oxygen bond to give protonated ethylene oxide fragment ions. ESMS is used to show that the products of the photocatalytic decomposition of SAE are the same as those produced by the collisionally activated decompositions. The surfactants can also be singly ionised in solution

A quartz crystal microbalance (QCM) technique has been employed to examine the detergency process involved when solid organic soils are removed from hard surfaces by surfactants. Experiments have been designed to focus on real time monitoring of the physicochemical aspects of detergency. Two model soils, tripalmitin and dotriacontane, have been investigated. Water absorption by the model soils has been monitored, through the change in resonance frequency of the coated crystal, as a function of time of immersion in high purity water solutions. Water and surfactant absorption and the rate of removal of the model soils upon immersion of the coated QCM crystal in aqueous surfactant solutions have also been monitored. Specifically, results obtained with the surfactants pentaethylene glycol mono-n-dodecyl ether (C12E5) and octaethylene glycol mono-n-dodecyl ether (C12E8) have shown that the QCM technique can be employed to identify several distinct stages in the soil removal process and to rank surfactants in terms of their ability to remove solid organic soils.

The Microtox test uses the marine luminescent bacterium, Photobacterium phosphoreum. To provide the organism with osmotic protection, sodium chloride (2.0%) is usually added to freshwater samples before analysis. This procedure is shown to cause a dramatic lowering of measured toxicity where ionic compounds are the major toxicants present. The reason for this is the consequent variation in ionic strength upon addition of NaCl rather than formation of less-toxic chloro complexes. Data are given for the toxicants Zn, Cd, Cu, NH4+, and phenol.It was found that measurements on aqueous samples could be made without adjustment provided that the salinity was in the range of 1.0-7.0%. Freshwaters can also be analyzed without adjustment of ionic strength by adding sucrose (20.4%) to provide the necessary osmotic protection.It is therefore recommended that the ionic strength of aqueous samples should not be altered as part of the test and that receiving waters should be used as the diluent wherever possible.