The chemistry of the carbon–transition metal double and triple bond: Annual survey covering the year 2005

Synthesis and Properties of Ferrocenyl Allenylidene Complexes: X-ray Structure of [Ru(C═C═CHFc)(PPh3)2(η5-C5H5)][PF6]·CH2Cl2

“…Research to date on higher order cumulenylidene complexes has been hampered on account of synthetic challenges and the instability of products, although a number of butatrienylidene and pentatetraenylidene complexes have been reported, − and only very recently have the very first examples of heptahexaenylidene complexes, [(CO) 5 MC(C) 5 C(NMe 2 ) 2 ] (M = Cr, W), been characterized . The literature of allenylidene complexes has been comprehensively assessed by Bruce through 1998, , and Cadierno et al to date, , with additional reviews appearing in the form of annual surveys − and metal-specific reviews encompassing chromium and tungsten, iridium, rhodium, manganese, and ruthenium. ,− Several comparative density functional theory treatments of cumulenylidene complexes have also been described. − …”

Prototypical Transition-Metal Carbenes, (CO)5Cr═CH2, (CO)4Fe═CH2, (CO)3Ni═CH2, (CO)5Mo═CH2, (CO)4Ru═CH2, (CO)3Pd═CH2, (CO)5W═CH2, (CO)4Os═CH2, and (CO)3Pt═CH2: Challenge to Experiment

“…6 Transition-metal carbenes have been synthesized with larger R groups on the carbon. 12,13 Furthermore, many molecules have been reported with MCH 2 bonds. These are generally Schrock-type transition-metal carbenes with ligands other than carbonyls surrounding the metal center.…”

Recent advances in the field of multicarbene and multimetal carbene complexes of the Fischer-type

“…4.) [34]. This bis(ethoxycarbene) intermediate of palladium (6) could be stabilized by incorporating the carbene ligands into fivemembered N,C-chelate rings [33,36]. Sierra and co-workers used palladium catalysts for intramolecular carbene-carbene coupling reactions of biscarbene complexes of Cr and W (Scheme 1, 7) to achieve a ring closure reaction with different outcomes for the final products depending on the precursors being of the o-dioxobenzene or o-diaminobenzene class of compounds [37].…”

“…The reactivity of Fischer carbene complexes containing α,β-unsaturated carbon substituents with a variety of organic substrates have been thoroughly investigated and extensively reviewed [1][2][3][4][5][6][7][8][9][10][11][84][85][86][87]. Well-known classes of monocarbene complexes used as precursors in organic synthesis via organometallic intermediates are those displaying carbene substituents with a-unsaturated carbon-carbon bonds.…”

“…Most of these Fischer monocarbene complex applications center around the reactivity of the metal-carbon double bond or the carbene-bonded heteroatom X (A in Fig. 1), or on modifications of vinyl-(B) or 1-alkynylcarbene ligands (C) for organic synthesis [1][2][3][4][5][6][7][8][9][10].…”