REACTIONS OF ORGANIC ISOCYANATES AND TERT-BUTYL ISOCYANIDE WITH MANGANESE(II) ALKYLS AND TRIMESITYLCHROMIUM

The dialklmanganese compounds [Mn(CH2Bu(t))2]4 and [Mn(CH2CMe2Ph)2]2 react with organic isocyanates to give chelating amido products that can be verified by hydrolysis to the amides. For Me3SiNCO the products of reaction with [Mn(CH2But)2]4 with 2 and 4 equivalents have been shown by X-ray crystallography to be, respectively, Mn3(CH2But)2[mu-OC(CH2But)N(SiMe3)]2(mu-CH2But)2 and Mn4(CH2But)2(mu(3)-NCO)2[mu-OC(CH2But)N(SiMe3)]4. In the triangular, and quite unsymmetrical, trinuclear species each manganese has a distorted four-co-ordinate geometry. Two manganese atoms are chelated by the amide ligands (Mn-O 2.208, 2.276 angstrom; Mn-N 2.149, 2.184 angstrom) the oxygen of which then bridge to a neighbouring metal atom. Two of the manganese atoms carry one terminal alkyl (Mn-C 2.122 and 2.154 angstrom) and one edge of the Mn3 triangle is bridged by one symmetrical (Mn-C 2.309 and 2.311 angstrom) and one unsymmetrical (Mn-C 2.184 and 2.646 angstrom) bridging alkyl. The tetranuclear species is centrosymmetric. One of the unique Mn atoms carries a terminal alkyl (Mn-C 2.092 angstrom) and is further co-ordinated by two bridging amide oxygens (Mn-O 2.070 and 2.073 angstrom) and one triply bridging cyanate nitrogen (Mn-N 2.282 angstrom). The other independent manganese is chelated by two amides with Mn-O 2.308 and 2.359 angstrom, Mn-N 2.146 and 2.176 angstrom, and its six-co-ordination is completed by bonds to both triply bridging cyanate groups with Mn-N 2.298 and 2.138 angstrom. The reaction of Cr(mes)3(thf) (mes = 2,4,6-Me3C6H2, thf = tetrahydrofuran) with BuNCO gives Cr[OC(mes)NBut]3. Similar interactions using Bu(t)NC lead to Mn[ButCH2C = NBut]2(PMe3) and Cr[(mes)C = NBut]3.