Quadruple bond Quadruple bond A quadruple bond is a type of chemical bond between two atoms involving eight electrons. This bond is an extension of the more familiar types double bonds and triple bonds. Stable quadruple bonds are most common among the transition metals in the middle of the d-block, such as rhenium, tungsten, molybdenum and chromium. Typically the ligands that support quadruple bonds are π-donors, not π-acceptors. Chromium(II) acetate, Cr("μ"-OCCH)(HO), was the first chemical compound containing a quadruple bond to be synthesized. It was described in 1844 by E. Peligot, although its distinctive bonding was not recognized for more than a
Owned-and-operated television stations in the United States opened up a new spectrum of frequencies on the UHF dial (channels 14–83) for terrestrial television. As an incentive for companies to operate UHF stations, the FCC relaxed the ownership limit for a given entity from five to seven stations, provided that no more than five were on the VHF dial. With this opportunity to expand its roster of O&Os, NBC bought WBUF-TV (channel 17) in Buffalo in 1955 and WKNB-TV (channel 30) in New Britain, Connecticut (near Hartford) in 1957, and changed WKNB's call letters to WNBC-TV (the present-day WNBC in New York City used the WRCA-TV callsign from