Comparisons (25 degrees C) are made of substitution reactions, X replacing H(2)O, at the tetrahedral Ni of the heterometallic sulfido cuboidal cluster [Mo(3)NiS(4)(H(2)O)(10)](4+), I = 2.00 M (LiClO(4)). Stopped-flow formation rate constants (k(f)/M(-)(1) s(-)(1)) for six X reagents, including two water soluble air-stable phosphines, 1,3,5-triaza-7-phosphaadamantane PTA (119) and tris(3-sulfonatophenyl)phosphine TPPTS(3)(-) (58), and CO (0.66), Br(-) (14.6), I(-) (32.3), and NCS(-) (44) are reported alongside the previous value for Cl(-) (9.4). A dependence on [H(+)] is observed with PTA, which gives an unreactive form confirmed by NMR as N-protonated PTA (acid dissociation constant K(a) = 0.61 M), but in no other cases with [H(+)] in the range 0.30-2.00 M. The narrow spread of rate constants for all but the CO reaction is consistent with an I(d) dissociative interchange mechanism. In addition NMR studies with H(2)(17)O enriched solvent are too slow for direct determination of the water-exchange rate constant indicating a value <10(3) s(-)(1). Equilibrium constants/M(-)(1) for 1:1 complexing with the different X groups at the Ni are obtained for PTA (2040) and TPPTS(3)(-) (8900) by direct spectrophotometry and from kinetic studies (k(f)/k(b)) for Cl(-) (97), Br(-) (150), NCS(-) (690), and CO (5150). No NCS(-) substitution at the Ni is observed in the case of the heterometallic cube [Mo(3)Ni(L)S(4)(H(2)O)(9)](4+), with tridentate 1,4,7-triazacyclononane(L) coordinated to the Ni. Substitution of NCS(-) for H(2)O, at the Mo's of [Mo(3)NiS(4)(H(2)O)(10)](4+) and [Mo(3)(NiL)S(4)(H(2)O)(9)](4+) are much slower secondary processes, with k(f) = 2.7 x 10(-)(4) M(-)(1) s(-)(1) and 0.94 x 10(-)(4) M(-)(1) s(-)(1) respectively. No substitution of H(2)O by TPPTS(3)(-) or CO is observed over approximately 1h at either metal on [Mo(3)FeS(4)(H(2)O)(10)](4+), on [Mo(4)S(4)(H(2)O)(12)](5+) or [Mo(3)S(4)(H(2)O)(9)](4+).

No abstract

No abstract

No abstract

The reaction of Pd black with [Mo 3 Se 4 (H 2 O) 9 ] 4ϩ in 2 M HCl gives the single cube [Mo 3 (PdCl)Se 4 (H 2 O) 9 ] 3ϩ , which on removal of Cl Ϫ forms the edge-linked double cube [{Mo 3 PdSe 4 (H 2 O) 9 } 2 ] 8ϩ . No similar reactions of [W 3 S 4 (H 2 O) 9 ] 4ϩ and [W 3 Se 4 (H 2 O) 9 ] 4ϩ are observed, and in no case is Pt black incorporated into the trinuclear species. The crystal structure of [{Mo 3 PdSe 4 (H 2 O) 9 } 2 ](pts) 8 ؒ18H 2 O has been determined (pts Ϫ = p-toluenesulfonate), and is consistent with Mo-Mo and Mo-Pd bonding. Properties of the Pd derivatives of both [Mo 3 Q 4 (H 2 O) 9 ] 4ϩ (Q = S, Se) are considered. No heteroatom transfer is observed on mixing [Mo 3 (PdCl)Se 4 (H 2 O) 9 ] 3ϩ with [Mo 3 S 4 (H 2 O) 9 ] 4ϩ as is the case of [Mo 3 SnSe 4 (H 2 O) 12 ] 6ϩ with [Mo 3 S 4 (H 2 O) 9 ] 4ϩ . The single cubes [Mo 3 (PdCl)Q 4 (H 2 O) 9 ] 3ϩ (Q = S, Se), react 1 : 1 with SnCl 3 Ϫ to give [Mo 3 (PdSnCl 3 )Q 4 (H 2 O) 9 ] 3ϩ with Pd-Sn bonding. Formation constants K (25 ЊC) are 1.15 × 10 3 M Ϫ1 (Q = S) and 9.5 × 10 3 M Ϫ1 (Q = Se). On mixing the heterometal cubes [Mo 3 PdS 4 (H 2 O) 10 ] 4ϩ and [Mo 3 SnS 4 (H 2 O) 12 ] 6ϩ in 2 M HCl no Pd-Sn bonding occurs. With [Pd(H 2 O) 4 ] 2ϩ and [Mo 3 SnS 4 (H 2 O) 12 ] 6ϩ in 2.0 M HClO 4 , reaction steps Mo 3 SnS 4 6ϩ Mo 3 S 4 4ϩ ϩ Sn II , followed by Sn II ϩ Pd II Sn IV ϩ Pd 0 are observed, and Pd 0 is precipitated. Rate constants for the oxidation of [Mo 3 (PdCl)S 4 (H 2 O) 9 ] 4ϩ and [{Mo 3 PdS 4 (H 2 O) 9 } 2 ] 8ϩ with [Co(dipic) 2 ] Ϫ (dipic = 2,6-pyridinedicarboxylate) are within a factor of 2, indicating no significant change in redox properties. This contrasts with the behaviour of single and corner-shared double cubes e.g. MЈ = Sn.