Synthesis and Characterization of the Complete Series [(C₅H_5‐n Cl_n)Co(C₄Ph₄)] (n=1–5)

Abstract

Reflux of a mixture of [CoCl(PPh 3 ) 3 ], Tl(C 5 H 4 Cl) and PhCCPh in toluene gave [(C 5 H 4 Cl)Co(C 4 Ph 4 )] in ca. 20 % yield. Deprotonation of this compound by lithium tetramethylpiperidinide (LiTMP) at À 30°C in THF, followed by addition of C 2 Cl 6 at À 78°C yielded [(C 5 H 3 Cl 2 )Co(C 4 Ph 4 )]. By repeating this proce-dure, the other members of the series [(C 5 H 5-n Cl n )Co(C 4 Ph 4 )] (n = 1-5) could be prepared in high yields. The molecular structures of the complexes with n = 3-5 were determined by X-ray crystallography.

(η4-Tetraphenylcyclobutadiene)-(η5-pentaphenylcyclopentadienyl)-cobalt

“…The distances between the cyclopentadienyl carbon and the phenyl ipso carbons are longer than the corresponding distances at the cy tadiene ring (average distance, 1.484(4) vs. 1.469(4) Å ). Whereas all phenyl rings a out of the planes of the co-ordinated rings away from the Co atom, this effect is st in the cyclobutadiene ring (average bending angle [2,4] [23], NICDIM [24], POHXAL [25], REXNEO [26], TUPQAW [27]), an contain a [Co(C4Ph4)(C5R5)] (R ≠ H) core (MEYQAI, MEYQOW [28], NEVDAT [29 UQUE [22]). Although many structures have two C5Ph5 rings (including [Co(C5 POHXAL), none has exclusively two C4Ph4 rings.…”

“…We decided to use the mentioned C5Ph5 structures (except for REX which is a binuclear compound) and the C4Ph4 structures NEVDAT, UZUQUE, MUL10 and [Co(C5H5)(C4Ph4)] (CPBUCO01, [30] for comparison with compound relevant data are presented in Table 1. ] core (GAHRUC [23], NICDIM [24], POHXAL [25], REXNEO [26], TUPQAW [27]), and four contain a [Co(C 4 Ph 4 )(C 5 R 5 )] (R = H) core (MEYQAI, MEYQOW [28], NEVDAT [29], UZUQUE [22]). Although many structures have two C 5 Ph 5 rings (including [Co(C 5 Ph 5 ) 2 ] + , POHXAL), none has exclusively two C 4 Ph 4 rings.…”

“…The latter phenomenon has only been studied for symmetrical metallocenes with two penta-aryl-cyclopentadienyl rings. As we recently started, to study half-sandwich complexes of the [Fe(C 5 Ph 5 )(CO) 2 R] type, as well as mixed sandwich complexes of the [Co(C 4 Ph 4 )(C 5 X 5 )] type [21,22], we decided to look into the synthesis, as well as the spectroscopic and structural properties of [Co(C 5 Ph 5 )(C 4 Ph 4 )], the first perphenylated mixed-sandwich complex.…”

“…A search in the Cambridge Structural Database (accessed on 2 November 2022) shows 125 entries for [M(C 5 Ph 5 )] fragments and 220 entries for [M(C 4 Ph 4 )] fragments. Of these, five contain a [Co(C 5 Ph 5 )] core (GAHRUC[23], NICDIM[24], POHXAL[25], REXNEO[26], TUPQAW[27]), and four contain a [Co(C 4 Ph 4 )(C 5 R 5 )] (R = H) core (MEYQAI, MEYQOW[28], NEVDAT[29], UZUQUE[22]). Although many structures have two C 5 Ph 5 rings (including [Co(C 5 Ph 5 ) 2 ] + , POHXAL), none has exclusively two C 4 Ph 4 rings.…”