RATE LAW VARIATIONS IN THE SPECIFIC MONOTRANSMETALATION OF (MU-4-O)(N,PY)4CU4-XMXX6 COMPLEXES WITH ZN(NS)2 IN NITROBENZENE

The copper(II) centers of the heteropolymetallic target family (μ4-O)(N,py)4Cu4−x,MxX6 are specifically replaced with M′ from M′(NS)n transmetalators by monotransmetalation in nitrobenzene. Here, N is N,N′-diethylnicotinamide, py is pyridine, x = 1–3, M is Co or Ni(H2O), X is Cl or Br, M′ is Co, Ni, or Zn, NS is monoanionic S-methyl isopropropylidenehydrazinecarbodithioate, and n = 2 (n = 3 only for M′ = Co). The rate laws for reaction of (μ4-O)(N,py)4Cu4Cl6 (A) with Co(NS)2 (B1), Ni(NS)2 (B2), and Zn(NS)2 (B3) are first-order in [B] and second-order in [A] (i.e., third-order overall). Although the monotransmetalation of (μ4-O)N4Cu(Ni(H2O)3Cl6 (NCuNi3Cl) with B2 also is third-order, its reactions with B1 and B3 are governed by rate = k4β1[NCuNi3Cl][B1 or B3]/(l + β1[NCuNi3Cl]), which demonstrates the involvement of “sticky” 1:1 reaction precursors with determinable stability constants β1 The rate laws for specific monotransmetalation of other members of the family (μ4-O)-(N,Py)4Cu4−xMxX6 (D) by B3 have been investigated as a function of ligand N or py, M = Co or Ni(H2O), X = Cl or Br, and x. Interactions between heteropolymetallic targets D and B3 are “stickier” than are those with homometallic targets A. Pronounced stickiness is ascribed to the presence of Ni-X-Cu edges and CuNi2 faces in (μ4-O)(N,py)4Cu4−x(Ni(H2O))xX6 targets. © 1990, American Chemical Society. All rights reserved.