A set of previously unknown tricoordinate hypervalent pnictogen compounds, 10-Pn-3 ADPnO, has been synthesized. The chemistry of these systems has been studied. Reactions with alcohols, a-dicarbonyl compounds, halogens, transition metals, protic acids, and acetylenes are among the chemistry described. In general, it was found that 10-As-3 ADAsO and 10-Sb-3 ADSbO systems behave similarly and offer different chemistry from that of the 10-P-3 ADP0 system. Among these unusual reactions is a novel C-C bond-forming reaction with hexafluoro-2-butyne. The electronic structure of these systems has been considered in light of preliminary ab initio molecular orbital calculations. The cyclic voltammetry data on the 10-Pn-3 ADPnO systems have been measured and are in accord with theoretical expectations. X-ray structures on a wide variety of derivatives provide insight into the chemistry of these systems. Phosphorus compounds with coordination numbers ranging from 2 to 6 have been characterized, and a trend is observed for ''P-l5N coupling constants and phosphorus coordination number.Our interest in transargononiclb compounds with low coordination number but high electron count has led us to investigate a family of compounds, 10-Pn-31C 5-aza-2,8-dioxa-l-pnictabicyclo[ 3.3.0]octa-2,4,6-triene (ADPnO) (Pn = pnictogen: N, P, As, Sb, Bi).2a33s4 In preliminary reports we have briefly der*? 10-Pn-3 8-Pn-3 ADPnOPn = Pnictogen (N, P, As, Sb, Bi) scribed the synthesis and structures of the three central members of this unusual family.2a,3s4 These ADPnO ring systems afford a unique opportunity t o examine the electromorphism*" between the 8-Pn-3 and 10-Pn-3 structures and hence gain new insight into 0002-7863/87/1509-0627$01.50/0 0 1987 American Chemical Society (IS) The 30.48-MHz "NI'HI magnetic resonance spectra were obtained using a DEPT pulse sequence: Doddrell. D. M.; Pcgg, D. T.; Bcndall. M. R. J . Mogn. Reson. 1982. 48,323. MLEV 16 deeaupling was used during the acquisition. The final p~oton pulse was set to a 45-angle and ,('/*a set between 50 and 125 ms. (16) (a) Nitrogen-IS Nuclear Magnetic Resononce S p e~I r o~c~p y : Levy.

A. Complexes with the Transition Group 6 1230 Metals, Cr and W B. Complexes with the Transition Group 7 1230 Metal, Mn C. Complexes with the Transition Group 8 1231 Metals, Fe and Ru D. Complexes with the Transition Group 10 1232 Metals, Ni, Pd, and Pt E. Complexes with the Transition Group 11 1234 Metal, Ag X. Conclusions 1235 XI. Abbreviations 1236 XII. References 1236 I. Introduction This review marks 10 years of research into the chemistry of low-coordinate hypervalent phosphorus compounds.1 The first tricoordinated hypervalent phosphorus compound, 10-P-323,7-di(tert-butyl)-5-aza-2,8dioxa-l-phosphabicyclo[3.3.0]octa-2I4,6-triene (AD-PO),3 was reported in 1983.4 Another type of 10-P-3 intermediate, 1, was discovered by Schmid peter and Lochschmidt in this same time frame.5 The work by Schmidpeter et al. and Arduengo et al. represent two different ligand designs to stabilize the 11n memory of Linus Amadeus and Schroeder. * Contribution no. 6745 from DuPont Science and Engineering Laboratory. * DuPont. I Himont. Anthony J. Arduengo, III (b 1952) was raised In Atlanta, GA. He received the Bachelor of Science degree (with honor) in chemistry from The Georgia Institute of Technology (1974) and Ph.D. in organic chemistry from the same Institution in 1976. After a year In Industry with DuPont's Central Research Department, he joined the organic chemistry faculty of The University of Illinois-Urbana. In 1984 he returned to DuPont where he has held various positions and Is currently a Research Leader in the Polymer Science Section of the Central Science and Engineering Laboratory. He has served on the editorial boards of Chemical Reviews and Heteroatom Chemistry as well as the IUPAC commission on Inorganic nomenclature. His research interests are broadly in the area of main group element chemistry with particular interest in compounds with unusual valence. Hobbies include trumpet playing, bicycling, antique cars, and classical music. Constantine A. Stewart was born in 1957 in San Angelo, TX. He received his Bachelor of Arts in chemistry (1980) from Texas Tech University in Lubbock, TX, and his Ph.D. in inorganic chemistry from the University of Texas at Austin (1984). He spent two years as a Visiting Research Scientist at Central Research and Development at DuPont. In 1986 he joined Himont U.S.A., Research and Development. He is currently working In the field of Ziegler-Natta catalysis. His hobbies include bicycling and photography.T-shaped 10-P-3 geometry. Both designs employ a bicyclic five-membered ring effect to stabilize an axialequatorial-axial chelation of the central pseudo-trigonal

The electrochemical reduction of VO2+ in acidic solution at high overpotentials Gattrell, M.; Qian, J.; Stewart, C.; Graham, P.; MacDougall, B.Contact us / Contactez nous: nparc.cisti@nrc-cnrc.gc.ca.

The X-ray. crystal structures of bis(cyc1o-pentadieny1)tin (1) and the new compound bis(penta-methylcyclopentadieny1)lead (2) show that (i) both compounds are monomeric in the solid state and (ii) the C,H, and Me,C5 rings in compounds (1) and (2), respectively, are bonded in the pentahapto-manner .

assistance.Registry No. [Co(bpy)2(PN-H)](C104)2, 100229-36-5; [Cu(bpy)-(PN)C1](C104).H20, 100229-39-8. Supplementary Material Available: Listings of thermal parameters, positional parameters of the hydrogen atoms, selected torsion angles and asymmetry parameters, least-squares planes, bond lengths and angles in bpy moieties, and observed and calculated structure factors and packing diagrams (Figures 3 and 4) (48 pages). Ordering information is given on any current masthead page.