Syntheses and crystal structures of [(Ph3As)(2)CCN-MnBr3], [(Ph3As)(2)CCN-CoBr3], and [(Ph3As)(2)CCN]+CuBr2-

The di(arsa)acetonitrilium bromide [(Ph3As)(2)CCN]Br reacts with the anhydr ous dibromides of manganese and cobalt in acetonitrile to form the molecula r complexes [(Ph3As)(2)CCN-MBr3] [M=(1), Co(2)] with zwitterionic structure s. With copper(I)bromide, however, the ionic compound [(Ph3As)(2)CCN]+CuBr2 - (3) is formed. All complexes are characterized by IR spectroscopy and by crystal structure analyses. 1 and 2 crystallize isotypically with each othe r in the space group P (1) over bar with two formula units per unit cell. T he MBr3- fragments in the molecular complexes are connected to the N atom o f the [(Ph3As)(2)CCN](+) cation showing bond angles C-N-Mn of 156.9 degrees and C-N-Co of 161 degrees, and distances Mn-N of 215.6 pm and Co-N of 201 pm. In 3, on the other hand, (space group C2/c, Z=4) the ions [(Ph3As)(2)CC N](+) and the linear Br-Cu-Br- ion are to be found concurrent but separate.