Experimental Evidence of Phosphine Oxide Generation in Solution and Trapping by Ruthenium Complexes

Highly Selective Microsensor for Monitoring Trace Phosphine in the Environment

Monitoring P flux at the Earth's surface-atmosphere interface has many challenges. Therefore, the development of a technology with high selectivity and high sensitivity to in situ trace PH₃ in aquatic or sedimentary environments has become a priority. Herein, an amperometric PH₃ microsensor meeting the above conditions is developed. The sensor is equipped with a Au-coated Pt working electrode (WE) and a Pt guard electrode (GE) positioned in an outer glass casing. The WE and GE are polarized at a fixed value of +150 mV with respect to a pseudo-reference electrode. The outer casing is filled with an acid electrolyte solution, and the tip is sealed using a thin silicone membrane. Mixed gases from the environment diffuse through the first layer of the silicone membrane, and the major H₂S disruptor is eliminated by a ZnCl₂-propylene carbonate trap positioned in the front of the microsensor. Later, the gases diffuse into an electrolytic solution through the second layer of the silicone membrane, and PH₃ is selectively oxidized into H₃PO₄ on the Au-coated Pt WE. This electrochemical oxidation thereby creates a current that is proportional to the concentration of PH₃ (>2 nmol·L^-1). With the aid of the H₂S trap casing and selective catalysis, the effects of other gases on the microsensor can be ignored in terms of environmental monitoring. An example from the sedimentary profile shows that high PH₃ accumulations are found 13 mm below the sediment surface.

A Stable Primary Phosphane Oxide and Its Heavier Congeners

(Ferrocenylmethyl)phosphane (1) oxidation with hydrogen peroxide, elemental sulfur and grey selenium produced (ferrocenylmethyl)phosphane oxide 1O, sulfide 1S and selenide 1Se, respectively, as the first isolable primary phosphane chalcogenides lacking steric protection. At elevated temperatures, compound 1O disproportionated into 1 and (ferrocenylmethyl)phosphinic acid. In reactions with [(η⁶ -mes)RuCl₂ ]₂ , 1O underwent tautomerization into a phosphane complex [(η⁶ -mes)RuCl₂ {FcCH₂ PH(OH)-κP}], whereas 1S and 1Se lost their P-bound chalcogen atoms, giving rise to the phosphane complex [(η⁶ -mes)RuCl₂ (FcCH₂ PH₂ -κP)] (Fc=ferrocenyl, mes=mesitylene). No tautomerization was observed in the reaction of 1O with B(C₆ F₅ )₃ , which instead produced a Lewis pair FcCH₂ P(O)H₂ -B(C₆ F₅ )₃ . Phosphane oxide 1O added to C=O bonds of aldehydes and ketones and even to cumulenes PhNCE (E=O and S). However, both PH hydrogens were only employed in the reactions with aldehydes and cyanates.

Iodine activation of coordinated white phosphorus: formation and transformation of 1,3-dihydride-2-iodidecyclotetraphosphane

Double stabilization: Previously unknown polyphosphorus compounds are obtained by activation of white phosphorus (P(4)) coordinated between two CpRu(PPh(3))(2) moieties with iodine, and subsequent hydrolysis. The polyphosphorus compounds (P(4) H(2) I, P(4) H(2), P(3) H(5); see scheme, Cp=cyclopentadienyl) are all stabilized by coordination to two ruthenium centers.