The synthesis of a tris(pyrazolyl)borate-stabilized molybdenum (VI) imido alkylidene complex, TpMo(CHC(Me)2Ph)(NAr) (OTf) (1) [Ar= 2,6-i-Pr2-C6H3,Ph=C6H5,OTf=OSO2CF3], has been achieved by addition of potassium hydridotris(1-pyrazolyl)borate (KTp) to Mo(CHC(CH3)2Ph)(NAr)(OTf)2(DME). Stirring compound1 over alumina in the presence of H2O gave TpMo(CH2C(Me)2Ph)(NAr)(O) (2). Alternatively, compound1 was converted to2 by the addition of CsOH·H2O in THF. A single crystal of [TpMo(NAr)(O)]2O (4) was isolated from a solution of2. Compounds2 and4 have been characterized by X-ray crystallography and the bonding considerations about the molybdenum atoms are discussed.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanism of the Formation of a Tungsten(VI) Alkylidene Complex Which Undergoes Reversible Metalation of an Ancillary LigandWilliam M. Vaughan, Khalil A. Abboud, and James M. BoncellaCite this: J. Am. Chem. Soc. 1995, 117, 44, 11015–11016Publication Date (Print):November 1, 1995Publication History Published online1 May 2002Published inissue 1 November 1995https://pubs.acs.org/doi/10.1021/ja00149a028https://doi.org/10.1021/ja00149a028research-articleACS PublicationsRequest reuse permissionsArticle Views129Altmetric-Citations22LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (2)»Supporting Information Supporting Information Get e-Alerts

The title compound, (2,6-diisopropylphenylimido)[hydrotris(1-pyrazolyl-N 3 )borato](2-methyl-2-phenylpropylidene) (trifluoromethanesulfonato) molybdenum(VI), [MO(CF 3 O 3 S)(C 10 H 12 )(C 12 H 17 N)(C 9 H 10 BN 6 )], has been synthesized and its crystal structure determined. The geometry around the Mo atom, imposed by the tridentate tris(pyrazolyl)borate ligand, is that of a distorted octahedron. There appears to be significant interaction between the ligands and the transition metal center. Principal distances include Mo-N(imido) 1.753(8), Mo-C(propylidene) 1.949(10), Mo-O(trifluoromethanesulfonate) 2.121(7) and Mo-N(pyrazolyl) 2.167 (8)2.311(9) A.

The addition of LiCH3 to TpMo(CHR)(NAr)(OTf) (1; Tp = hydridotris(1-pyrazolyl)borate; R = C(CH3)(2)Ph; Ar = 2,6-i-Pr-C6H3; OTf = OSO2(CF3)) gave TpMO(CHR)(NAr)(CH3) (2). Compound 2 was used to prepare several solvent-bound, cationic complexes by abstracting the methyl ligand. The addition of tetrakis(3,5-bis(trifluoromethyl)phenyl)boric acid to 2 in Et(2)O gave [TpMo(CHR)(NAr)(Et(2)O)][BAr'(4)] (3; Ar' = 3,5-C6H3(CF3)(2)) and CH4. The reaction of 2 and trityl tetrakis(pentafluorophenyl)borate in the presence of excess acetonitrile gave [TpMo(CHR)(NAr)(NCCH3)][B(C6F5)(4)] (4) and Ph(3)CCH(3). The Lewis acid B(C6F5)(3) abstracted the methyl ligand of 2 in the presence of acetonitrile or tetrahydrofuran to give the compounds [TpMo(CHR)(NAr)(S)][B(CH3)(C6F5)(3)] (5, S = NCCH3; 6, S = THF). The triflate ligand of 1 was displaced by trimethylphosphine to give [TpMo(CHR)(NAr)(P(CH3)(3))][OTf] (7). Stirring 1 in the presence of methanol and Florisil gave TpMo(CHR)(NAr)(OCH3) (8). The addition of excess potassium methoxide to 1 gave TpMo(CR)(NHAr)(OCH3) (9). Attempts to convert 8 to 9 by heating, photolysis, and the addition of NEt(3) or PMe(3) were unsuccessful. Since only excess methoxide converts 8 to 9, a methoxide-mediated proton transfer mechanism is proposed. X-ray structures of syn-8 (P2(1)2(1)2(1), a = 12.620(2) Angstrom, b = 13.492(2) Angstrom, c = 19.682(2) Angstrom, Z = 4, V = 3351.3(7) Angstrom(3), M(r) = 647.48, d(calc) = 1.283 g/cm(3), R = 6.00%, R(w) = 5.89%) and syn-9 (P ($) over bar 1, a = 10.624(2) Angstrom, b = 11.766(2) Angstrom, c = 13.980(2) Angstrom, alpha = 86.96(2)degrees, beta = 86.54(2)degrees, gamma = 67.77(2)degrees, Z = 2, V = 1635.8(7) Angstrom(3), M(r) = 647.48, d(calc) = 1.283 g/cm(3), R = 4.84%, R(w) = 4.87%) were obtained, and a trans-influence series has been established for several ligands. Rotational isomers due to rotation about the Mo-alkylidene bond were observed for all compounds, and marked differences in rates of rotamer interconversion are observed for 1, 2, and 8. Compounds 1 and 2 in the presence of AlCl3 successfully catalyzed the ring-opening metathesis polymerization of cyclooctene and norbornylene and the oligomerization of 1,9-decadiene via acyclic diene metathesis polymerization.

The study focuses on the sulfur budget in large power plant and urban-industrial plumes. In low stacks the total sulfur flow rate decreases with distance: only about one-third of the original emissions are transported beyond a radius of 100 km. Evidence indicates that the formation of aerosol begins after an aging time of 1-2 h. In power plant plumes, the sulfur emitted from tall stacks leaves the region of 50-100 km essentially at the same rate as it is emitted at the source. Maps and graphs are included.