ISOLATED VERSUS CONDENSED ANION STRUCTURE-IV - AN NQR STUDY AND X-RAYSTRUCTURE-ANALYSIS OF [H3N(CH2)(3)NH3]CDI4-CENTER-DOT-2H(2)O, [H3CNH2(CH2)(3)NH3]CDBR4, [(CH3)(4)N](2)CDBR4, AND [C(CH3)(3)S](2)CDBR4

The phase I of [H3N(CH2)(3)NH3]CdI4. 2H(2)O (1) crystallizes with isol ated [CdI4](2-) tetrahedra; monoclinic, C2/c, Z = 8, a = 1702.6(3), b = 1459.3(3), c = 1555.5(3) pm, and beta= 120.32(3)degrees at 299 K. (1 ) shows a first-order phase transition at TI<->II = 245 K. The eight I -127(nu(1)) NQR lines in phase II change discontinuously into four lin es in phase I. The transition entropy from DSC measurements, Delta S=5 .0 J K-1 mol(-1), shows that this transition is probably due to order- disorder of cations. [H3CNH2(CH2)(3)NH3]CdBr4 (2) crystallizes with is olated [CdBr4](2-) tetrahedra; orthorhombic P2(1)2(1)2(1), Z = 4, a = 1447.8(5), b = 1280.3 (4), c = 709.7(3) pm at 299 K. (2) shows four Br NQR lines between 77 and around 325 K, above which temperature the li nes disappear. [(CH3)(4)N](2)CdBr4 (3) shows a second-order phase tran sition at T1<->II = 271 K. Three of four Br-81 NQR lines in phase II d isappear below this transition point, the other line can be observed u p to 315 K. The transition entropy, Delta S = 9.01 J K-1 mol(-1), indi cates that the transition is an order-disorder type of the cations. [( CH3)(3)S](2) CdBr4 (4) shows a first-order type phase transition at T1 <->II = 304 K. The four lines spectrum of Br-81 NQR is observed in pha se IT and disappears above the transition point. The transition entrop y, Delta S = 46.8 J K-1 mol(-1) is abnormally large. The role of the h ydrogen bond and the bridging power between the halogen and cadmium at oms upon the formation of the condensed anion structure is discussed.