Crystal structures, vibrational spectra and normal coordinate analyses of cis-(n-Bu4N)2[ReBr4(NCS)2], cis-(n-Bu4N)2[ReBr4(NCSe)2] and cis-(n-Bu4N)2[ReBr4(NCS)(NCSe)]

The crystal structures of cis-(n-Bu4N)(2)[ReBr4(NCS)(2)] (1) (triclinic, space group P (1) over bar, a = 11.475(6), b = 20.096(16), c = 22.144(11) Angstrom, alpha = 110.56(6), beta = 92.97(5), gamma = 99.77(7)degrees, Z = 4), cis-(n-Bu4N)(2)[ReBr4(NCSe)(2)] (2) (triclinic, space group P (1) over bar, a = 11.527(3), b = 20.237(7), c = 22.07(2) Angstrom, alpha = 110.05(4), beta = 93.86(6), gamma = 99.49(4)degrees, Z = 4) and cis-(n-Bu4N)(2)[ReBr4(NCS)(NCSe)] (3) (triclinic, space group P (1) over bar, a = 11.488(2), b = 20.164(6), c = 22.158(5) Angstrom, alpha = 110.44(2), beta = 93.34(2), gamma = 99.626(18)degrees, Z = 4) have been determined by single crystal X-ray diffraction analysis. Based on these molecular parameters the low temperature (10 K) IR and Raman spectra of the (n-Bu4N) salts have been assigned by normal coordinate analysis. The valence ford constants are f(d)(ReN) = 1.70 (1), 1.70 (2) and 1.72 (3), f(d)(ReBr)= 1.36 (1), 1.30 (2) and 1.36 mdyn/Angstrom (3).