Unprecedented co-ordination of a cyclo-octatetraene ligand. Synthesis and crystal and molecular structure of (η-pentamethylcyclopentadienyl)(1,4-η-octafluorocyclooctatetraene)(trimethylphosphine)rhodium(III)

Abstract

Photolysis of [Rh(q5-C5Me5)( I ,2,5,6-q-C8F8)] i n the presence of PMe3 leads to the crystallographically characterized title compound which contains a unique example of a 1,4-q-cyclo-octatetraene ligand; this compound is an intermediate en route t o formation of perfluorobicyclo[3.3.O]octadienediyl complexes.Cyclo-octatetraene (cot) has been a ligand of great significance in the development of organometallic chemistry. Its flexible hapticity has enabled compounds exhibiting a variety of co-ordination modes to be isolated.l.2 The transition metal chemistry of the corresponding fluorocarbon octafluorocyclooctatetraene (ofcot) (1) is significantly different3--5 and has

Reduction vs. Addition: The Reaction of an Aluminyl Anion with 1,3,5,7‐Cyclooctatetraene

“…9‐heteroatom substituted bicyclo[4.2.1]nona‐2,4,7‐triene ring systems are known for Si, Ge, P . The incorporation of metal atoms at this position is, however, rare with structurally characterized examples restricted to a trimetallic Pt 3 ‐complex and Rh(Cp*)(C 8 F 8 )(PMe 3 ) derived from per‐fluorinated COT . Interestingly, a related bimetallic species was proposed as the initial product of either [4π+2π] or [6π+2π] cycloaddition of the digallene to COT during the synthesis of V , but could not be structurally verified.…”

“…X-ray crystallography confirms that the crown ether was successful in segregating polymer [3] 9-heteroatom substituted bicyclo[4.2.1]nona-2,4,7-triene ring systems are known for Si, [6] Ge, [7] P. [30] Theincorporation of metal atoms at this position is,h owever, rare with structurally characterized examples restricted to atrimetallic Pt 3 -complex [31] and Rh(Cp*)(C 8 F 8 )(PMe 3 )d erived from perfluorinated COT. [32] Interestingly,arelated bimetallic species was proposed as the initial product of either [4p + 2p]o r [6p + 2p]c ycloaddition of the digallene to COTd uring the synthesis of V, [21] but could not be structurally verified. This intermediate was shown to exist in equilibrium in solution, and we propose that as imilar fluxionality is present in the aluminyl/COTs ystem described herein (Scheme 4).…”

“…Aloss of symmetry is also observed for the NON Arligand in 5,e videnced by inequivalent iPr and SiMe 2 signals. [32] Interestingly,arelated bimetallic species was proposed as the initial product of either [4p + 2p]o r [6p + 2p]c ycloaddition of the digallene to COTd uring the synthesis of V, [21] but could not be structurally verified. 9-heteroatom substituted bicyclo[4.2.1]nona-2,4,7-triene ring systems are known for Si, [6] Ge, [7] P. [30] Theincorporation of metal atoms at this position is,h owever, rare with structurally characterized examples restricted to atrimetallic Pt 3 -complex [31] and Rh(Cp*)(C 8 F 8 )(PMe 3 )d erived from perfluorinated COT.…”

Fluorine as a ligand substituent in organometallic chemistry: A second chance and a second research career

“…Scheme 2 illustrates some chemistry of OFCOT bound to Co and Rh; initial binding gives compounds 6 in which OFCOT is bound as a 1,5-diene, analogous to the COT analogues prepared earlier by Bennett and Saxby [29]. However, under the influence of ambient light rearrangement to 7 occurs [30,31]. Unlike the iron analogue 2, compounds 7 do not react with PMe 3 at the ligand but rather at the metal, with an h 3 !…”

“…Unlike the iron analogue 2, compounds 7 do not react with PMe 3 at the ligand but rather at the metal, with an h 3 ! h 1 rearrangement occurring to give 8 [31,32]. Slow rearrangement of 8 occurs via a transannular ring closure to afford 9, in which four fluorines have achieved ''sp 3 carbon status'' [33].…”