Syntheses and structures of six and seven-coordinate diene complexes of molybdenum and tungsten(II). The crystal and molecular structures of [WBr2(CO)2(PMePh2)(norbornadiene)] and [WBr2(CO)(NCCH=CH2)(norbornadiene)]

Jack L. Davidson, Heiko Richtzenhein, B. J S Thiebaut, Kai Landskron, Georgina M. Rosair

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Reactions of [WI2(CO)3(NCMe)2] with norbornadiene (NBD) and 1,5-cycloctadiene (COD) give six-coordinate dicarbonyls [WI2(CO)2(NBD)] and [WI2(CO)2(COD)], respectively. The related dibromo complex [WBr2(CO)2(NBD)] reacts with tertiary phosphines L to give unstable seven-coordinate adducts [WBr2(CO)2(L)(NBD)] (L=PPh3, PMePh2, PEt3), which in the case of L=PMePh2 was shown to undergo CO loss to give the six-coordinate derivative [WBr2(CO)(PMePh2)(NBD)]. X-ray diffraction studies of [WBr2(CO)2(PMePh2)(NBD)] reveal a seven-coordinate structure (distorted pentagonal bipyramid) with the diene C=C bonds on the pentagonal plane lying approximately parallel to the W-CO axes. Reactions of [WBr2(CO)2(NBD)] with organonitriles NCR at room temperature afford CO substitution products (R=Me, Pri, Ph, C6H4Me-4, CH=CH2) directly with no evidence for seven-coordinate intermediates. [WBr2(CO)2(COD)] and acetonitrile similarly give [WBr2(CO)(NCMe)(COD)]. X-ray diffraction studies of [WBr2(CO)(NCCH=CH2)(NBD)] confirmed a distorted octahedral structure where the carbonyl lies trans to the acrylonitrile ligand. © 1999 Elsevier Science S.A.

Original languageEnglish
Pages (from-to)168-179
Number of pages12
JournalJournal of Organometallic Chemistry
Volume592
Issue number2
Publication statusPublished - 25 Dec 1999

Keywords

  • Crystal structures
  • Norbornadiene
  • Seven coordination
  • Six coordination
  • Synthesis
  • Tungsten

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