The self-assembly method has been used to prepare a wide range of new adamantane-like anions of the type [(μ-SR)6(MX)4]2− (M = Zn or Cd; R = alkyl or benzyl; X = Cl, Br, or I) as their Et4N+ salts. Metal (111 or 113Cd) NMR data have been measured for the cadmium complexes, and also for many of the possible mixed-metal complexes [(μ-SR)6(CdX)n(ZnX)4−n]2−. In the complexes with mixed metals, the effects of Zn substitution on the metal chemical shifts are generally larger for the alkyl- and benzyl-thiolate complexes than for related benzenethiolate complexes. However, for [(μ-SPri)6(CdX)n(CdX′)4−n]2− (X/X′ = Cl/Br, Cl/I, or Br/I), substituent effects are no larger than found in some PhS−-bridged complexes. The reaction of [(μ-SPri)6(CdX)4]2− (X = Cl, Br, or I) with E′8 (E′ = S or Se) in CH2Cl2 gives [Cd4(μ4-E′) (μ-SPri)12(CdX)4]2− as the major species detectable by metal, 13C, and, where applicable, 77Se NMR. However, the reaction does not occur stoichiometrically. The compound (Et4N)2[(μ-SPri)6(CdBr)4] crystallizes in the monoclinic space group P21/c with cell dimensions a = 24.079(3) Å, b = 11.365(2) Å, c = 22.561(3) Å, β = 113.89(1), and Z = 4. The structure was refined to R(Rw) = 0.0663(0.0703) with the use of 2669 unique data with I > 2.5σ(I). The anion contains an adamantane-type (μ2-S)6Cd4 cage composed of a nearly regular Cd4 tetrahedron and a distorted S6 octahedron, the irregularity of which is caused by 1,3-interactions of the substituent groups on the sulfur atoms. The axial or equatorial dispositions of the six alkyl groups in the four fused M3S3 rings are [aae, aae, aee, aee]. For the zinc-group elements, this is the first example of an adamantane-like (μ-Salkyl)6M4 cage that has been characterized crystallographically. Keywords: cadmium complex, cadmium-111/113 NMR, thiolate complex, X-ray analysis, zinc complex.
Polyphosphate Poly(amine) Nanoparticles: Self-Assembly, Thermodynamics, and Stability Studies
