A Cyclopropenylidene Approach to Tricarbide Complexes:  Synthesis and Structure of [M(CO)₅{μ₂-C₃(OCH₂CH₃)}Fe(CO)₂(Cp)] (M = Cr, Mo, W)

Abstract

The diethoxycyclopropenylidene complexes [M(CO)5{C3(OCH2CH3)2}] (M = Cr, Mo, W) react with K[Fe(CO)2(Cp)] to give the bimetallic cyclopropenylidene complexes [M(CO)5{μ2-C3(OCH2CH3)}Fe(CO)2(Cp)], but the second ethoxide is not displaced by excess K[Fe(CO)2(Cp)]. Spectroscopic evidence (1H NMR, 13C NMR, and IR) as well as a X-ray crystal structure determination of [Cr(CO)5{μ2-C3(OCH2CH3)}Fe(CO)2(Cp)] suggests that the central C3 ring has a great deal of cyclopropenium character.

Carbon–Carbon Bond Formation at a Neutral Terminal Carbido Ligand: Generation of Cyclopropenylidene and Vinylidene Complexes

“…Unlike 3, however, the cyclopropenylidene units in these complexes are substituted by phenyl or electrondonating groups. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] [Ru(C)(H 2 IMes)(PCy 3 )Cl 2 ] (4; H 2 IMes = 4,5-dihydro-1,3-bis(mesityl)imidazol-2-ylidene) reacts similarly with DMAD, but the reaction is not clean since the product reacts further with DMAD before all of 4 has been consumed. However, 4 reacts more cleanly with HCCCO 2 Me (see the Supporting Information).…”

“…C 3 (NiPr 2 ) 2 (5) [25] and in other cyclopropenylidene complexes. [9,[14][15][16][17][18][19][20][21][22][23] The formation of 3 from 2 is interesting because the cyclopropylidene complex [Ru{ = CC 2 H 2 (CO 2 Me) 2 }-(PCy 3 ) 2 Cl 2 ] (6) is not observed as an intermediate when 2 is formed from 1 by reaction with Feists ester. [4] Addition of 2 equivalents or less of PCy 3 to [Ru{=CC 2 H 2 (CO 2 Me) 2 }-(PPh 3 ) 2 Cl 2 ] similarly yields 2.…”

Carbon–Carbon Bond Formation at a Neutral Terminal Carbido Ligand: Generation of Cyclopropenylidene and Vinylidene Complexes

“…[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] [Ru(C)(H 2 IMes)(PCy 3 )Cl 2 ] (4; H 2 IMes = 4,5-dihydro-1,3-bis(mesityl)imidazol-2-ylidene) reacts similarly with DMAD, but the reaction is not clean since the product reacts further with DMAD before all of 4 has been consumed. Although 2 does not react with a variety of alkenes and alkynes (see the Supporting Information), it reacts cleanly with MeO 2 CC CCO 2 Me (dimethyl acetylenedicarboxylate, DMAD) over 4 h in C 6 H 6 .…”

“…[24] Figure 1 depicts a thermal ellipsoid plot of one of the two chemically equivalent but crystallographically independent molecules of 3 in the crystal. [9,[14][15][16][17][18][19][20][21][22][23] The formation of 3 from 2 is interesting because the cyclopropylidene complex [Ru{ = CC 2 H 2 (CO 2 Me) 2 }-(PCy 3 ) 2 Cl 2 ] (6) is not observed as an intermediate when 2 is formed from 1 by reaction with Feists ester. The cyclopropenylidene ring lies in the Cl-Ru-Cl plane.…”

“…The structure shows significant bond localization in the cyclopropenylidene fragment. [14][15][16][17][18][19][20][21][22][23] Unlike 1, 3 does not react appreciably with common olefins or alkynes, although under some conditions small amounts of 2 are formed, suggesting reversibility of the 2!3 transformation (see the Supporting Information). [9,[14][15][16][17][18][19][20][21][22][23] The formation of 3 from 2 is interesting because the cyclopropylidene complex [Ru{ = CC 2 H 2 (CO 2 Me) 2 }-(PCy 3 ) 2 Cl 2 ] (6) is not observed as an intermediate when 2 is formed from 1 by reaction with Feists ester.…”