Issue 8, 2001

Molybdenum-based alkyne–isocyanide coupling reactions: synthesis of a reactive diiminometallacyclopentene complex

Abstract

The complex [Mo(CO)(PhC[triple bond, length as m-dash]CPh)2(η-C5Me5)][BF4] reacted with three equivalents of 2,6-dimethylphenyl isocyanide, CNxyl, to give the tris(isocyanide) complex [Mo(PhC[triple bond, length as m-dash]CPh)(CNxyl)3(η-C5Me5)][BF4] 1. With four equivalents of CNxyl, alkyne–isocyanide coupling leads to the formation of the diiminometallacyclopentene [[upper bond 1 start]Mo{C([double bond, length as m-dash]Nxyl)C(Ph)[double bond, length as m-dash]C(Ph)C[upper bond 1 end][double bond, length as m-dash]Nxyl}(CNxyl)2(η-C5Me5)][BF4] 2 which decomposes in thf at room temperature to give the tetrakis(isocyanide) complex [Mo(CNxyl)4(η-C5Me5)][BF4] 3. In dichloromethane, 2 gives the diiminocyclobutene xylN[double bond, length as m-dash][upper bond 1 start]CC(Ph)[double bond, length as m-dash]C(Ph)C[upper bond 1 end][double bond, length as m-dash]Nxyl 4, the η2-iminoacyl complex [MoCl(CNxyl)22-xylN[double bond, length as m-dash]CCH2Cl)(η-C5Me5)][BF4] 5, formed by an addition reaction with dichloromethane, and the metallacyclobutene complex [[upper bond 1 start]Mo{C(Ph)[double bond, length as m-dash]C(Ph)C[upper bond 1 end][double bond, length as m-dash]N(H)xyl}(CNxyl)3(η-C5Me5)][BF4]26. Complex 5 is more efficiently synthesized by photolysis of 3 in dichloromethane, but the same reaction in chloroform produces the dichloromethyl complex [MoCl(CHCl2)(CNxyl)3(η-C5Me5)][BF4] 7 which thermally decomposes to [MoCl2(CNxyl)3(η-C5Me5)][BF4] 8. Reaction of 2 with HCl in diethyl ether results in protonation of the metallacyclic ring and formation of the iminium metallacyclopentene [[upper bond 1 start]MoCl{C([double bond, length as m-dash]Nxyl)C(Ph)[double bond, length as m-dash]C(Ph)C[upper bond 1 end][double bond, length as m-dash]N(H)xyl}(CNxyl)2(η-C5Me5)][BF4] 9. Compound 3 is oxidised by AgBF4 to give the molybdenum(IV) complex [MoF(CNxyl)4(η-C5Me5)][BF4]210. The molecular structures of 3–6, 7/8 and 10 have been determined by X-ray crystallography.

Graphical abstract: Molybdenum-based alkyne–isocyanide coupling reactions: synthesis of a reactive diiminometallacyclopentene complex

Supplementary files

Article information

Article type
Paper
Submitted
15 Dec 2000
Accepted
20 Feb 2001
First published
27 Mar 2001

J. Chem. Soc., Dalton Trans., 2001, 1284-1292

Molybdenum-based alkyne–isocyanide coupling reactions: synthesis of a reactive diiminometallacyclopentene complex

C. J. Adams, K. M. Anderson, I. M. Bartlett, N. G. Connelly, A. G. Orpen, T. J. Paget, H. Phetmung and D. W. Smith, J. Chem. Soc., Dalton Trans., 2001, 1284 DOI: 10.1039/B010018H

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