The \dqsupershort\dq chromium-to-chromium quadruple bond: Its occurrence in a tetracarboxamidatodichromium(II) compound. Journal of the American Chemical Society, (101)9:2506--2507, 1979. [PUMA: acetamidatochromium bond carboxamidato chromium complex;chromium complex;substituent effect prepn crystal distance quadruple structure;bond]