Tricarbonylchromium complexes pyridine

The tricarbonylchromium (0) complex of pyridine 94 has also recently been shown to undergo selective lithiation at the C-2 position with LDA, to give 95 [JCS(P1)501]. However, this result is not synthetically significant since the starting material 94 was actually prepared by desilylation of the... 

The carbonyl complexes listed in Table V are of two types tricarbonyl-chromium rj6-arene 77-complexes, and pentacarbonyltungsten <7-pyridine complexes, with both complex types having relatively low y. Nonlinearities increase on arene or pyridine 77-system lengthening, and on proceeding from acceptor to donor substituent on the tricarbonylchromium-coordinated arene ring. Relative magnitudes and trends thus mirror those observed with quadratic nonlinearities of these complexes (see Ref. 1)... 

The acrylate- and methacrylate-derivatized r 5-(benzene)tricarbonylchromium monomers 20 65,66,68,72 21,69>72 and 2273 (Scheme 1.2) were synthesized from benzyl alcohol or 2-phenylethanol when reacted with Cr(CO)6. The alcohols were esterified with either acrylyl or methacrylyl chloride in ether/pyridine and purified by multiple recrystallizations from CS2. Homopolymerizations proceeded in classic fashion with no special electronic effects from the rr-complexed Cr(CO)3 moiety.65,73 Acrylate 20 was copolymerized with styrene and methyl methacrylate and the reactivity ratios were obtained.65 Acrylate 21 and methacrylate, 22, copolymerized readily with styrene, methyl acrylate, acrylonitrile, and 2-phenylethyl acrylate to give bimodal molecular-weight distributions using AIBN initiation.69 Copolymerization of 20 with ferrocenylmethyl acrylate, 2, generates copolymers with varying mole ratios of two transition metals, Cr and Fe (see structure 34).65... 

By analogy with the structure of hexaethylborazine tricarbonylchromium it was suggested that the bonding to cobalt is of the arene 7r-complex type. N3P3CI6 also forms complexes with pyridine and DMF, whose... 

Just as the tricarbonyliron group has been used as a protecting group for dienes, the tricarbonylchromium group has been used in a similar fashion to stabilize dihydropyridines which are normally difficult to handle and to isolate. The dihydropyridine is readily liberated from the complex by treatment with pyridine at room temperature (Kutney et ai., 1974). Dihydropyridines can also be generated from the corresponding tricarbonyliron complexes, recently synthesized by Alper (1975). 

Heteroleptic heterodinuclear m-Pd (C N)2 complexes such as 56 are obtained from the reaction of or/i o-mercurated 2-[(77 -phenyl)tricarbonylchromium]pyridine with /x-chloro cyclopalladated aromatic compounds in the presence of large amounts of [NMe4]Cl. The products are valuable precursors of planar chiral cyclopalladated Gr( 7 -arene)(GO)3 complexes, for example, 57. A series of or// o-palladated binuclear Gr(r7 -arene)(GO)3... 

The carbonyl complexes in Table XIV are of three types, tricarbonylchromium r] -arene complexes, pentacarbonyltungsten o-pyridine complexes, and car-bonylruthenium o-alkenyl complexes, the first two possessing low y values. For the first two types, lengthening the 7i-system or replacing acceptor by donor substituent on the tricarbonylchromium-coordinated arene ring results in... 

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