Formation, microwave spectrum and molecular constants of bismuth monochloride

Abstract

The microwave absorption spectrum of gaseous bismuth monochloride (BiCl) in the O + electronic ground state has been measured in the 55–100 GHz region. The molecule was produced by a double oven technique at 500°C. Rotational transitions (ν, J +1) ??? (ν, J) with J = 10, 12, 16 and 17 and ν up to 9 were observed for Bi 35Cl and with J = 10, 12, 17 and 18 and ν up to 5 for Bi 37Cl. The hyperfine structure due to the Bi and Cl nuclei is generally only partially resolved. Analysis yields the following rotational and hyperfine constants for Bi 35Cl: Y O1 = 2761.8538(13) MHz, Y 11 = −12.0526(11) MHz, Y 21 = 11.62(32) kHz, Y 31 = 43(25) Hz, Y 02 = −987.2(22) Hz, eq 0 Q(Bi) = −1027(12) MHz, eq 0 Q ( 35Cl) = −34.5(28) MHz, c Bi = −21(7) kHz. The results for Bi 37Cl are: Y 01 = 2634.0416(18) MHz, Y 11 = −11.2268(10) MHz, Y 21 = 10.95(20) KHz, Y 02 = −896.8(31) Hz, eq 0 Q (Bi) = −1025(28) MHz, eq Q ( 37Cl) = −27.1(38) MHz, c Bi = 18(22) kHz. From Dunham coefficients we deduce potential and vibrational constants and from hyperfine constants some information about chemical bonding in BiCl. The results are in agreement with the position of Bi in the periodic system which is intermediate between the elements of group III a and VII a.