FORMATION OF THE 1,4-DIAZABUTADIEN-2-YL COMPLEX TERISK)(4)(C(=NPH-ASTERISK)C(CH3)=N(PH-ASTERISK))] THROUGH METHYLATION OF A MANGANESE(-I) ISONITRILATE

Alkylation of [Mn(CNPh)(5)](-) with CH3I gives the 1,4-diazabutadien- 2-yl complex [Mn(CNPh)(4){C(=NPh*)C(CH3)=N(Ph*)}] (2) in a 30% yield, as established by a single-crystal X-ray diffraction study. The same product can be obtained in poor yield when CH3OSO2CF3 is used as the a lkylating agent,;Ind use of ethyl iodide gives the corresponding ethyl complex [Mn(CNPh)(4){C(=NPh*)C(CH2CH3)=N(Ph*)}] (3). It is proposed that the first step in the formation of 2 is alkylation at manganese: transient [Mn(CNPh)(5)CH3] is then converted into an iminoacyl comple x by isonitrile/alkyl insertion. Insertion of a second isonitrile into the metal-iminoacyl bond leads to the 1,4-diazabutadien-2-yl complex. The addition of free CNPh to the reaction solution leads to only a m odest increase in the yield of 2, but the importance of exogenous ison itrile is supported by the formation of [Mn((CNBu)-Bu-t)(CNPh)(3){C(= NPh)C(CH3)=N(Ph*)}] (4), in which 1 equiv of (CNBu)-Bu-t is coordinat ed to Mn, when (CNBu)-Bu-t is added to a solution of 1(-) before react ion with CH3I.