SYNTHESES, REACTIVITY, AND MOLECULAR STRUCTURES OF RSRS-[NI(TMC)SC6H5](PF6), RRSS-[NI(TMC)SC6H5](CF3SO3), AND RRSS-[NI(TMC)](CF3SO3) (TMC=1,4,8,11-TETRAMETHYL-1,4,8,11-TETRAAZACYCLOTETRADECANE)

摘要

The RSRS and RRSS isomers of [Ni(tmc)](OTf)2 (tmc = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane; OTf(-) = CF3SO3-) react with NaSC6H5 to yield the corresponding high spin, five-coordinate derivatives, [Ni(tmc)SC6H5](OTf). The molecular structure of each has been determined by X-ray diffraction. RRSS-[Ni(tmc)SC6H5](OTf) crystallized in the monoclinic space group P2(1), with a = 12.648(3) Angstrom, b = 15.145(4) Angstrom, c = 14.765(4) Angstrom, beta = 113.96(2)degrees, V = 2584(1) Angstrom(3), and Z = 4. The coordination sphere about Ni is best described as square pyramidal with a Ni-S bond distance of 2.369(2) Angstrom and Ni-N-av of 2.128 Angstrom. RSRS-[Ni(tmc)SC6H5]-(PF6) crystallized in the monoclinic space group P2(1), with a = 13.037(5) Angstrom, b = 15.407(7) Angstrom, c = 13.706(7) Angstrom, beta = 113.53(3)degrees, V = 2524(2) Angstrom(3), and Z = 4. The Ni resides in a highly distorted square pyramid with a shorter Ni-S distance, 2.352(2)Angstrom and correspondingly longer Ni-N-av distance of 2.149 Angstrom. Alternatively [Ni(tmc)SR](OTf) may be produced by oxidative addition of disulfide, R(2)S(2) (R = C6H5, C2H5), to Ni(tmc)(OTf). The second-order rate constant, k(i), for reaction with (C6H5)(2)S-2 is 120 M(-1)s(-1). (C2H5)(2)S-2 reacts 5 orders of magnitude more slowly consistent with its greater S-S bond dissociation energy. The nickel thiolates react with haloalkanes, RX (RX = CH3I, C2H5I, (CH3)(2)CHI, C6H5CH2Cl), producing [Ni(tmc)X](OTf) and C(6)H(5)SR. The reaction is second order with k(2) decreasing in the order, CH3I > C2H5I > (CH3)(2)CHI. Strikingly, for reactions with a given RX, the RRSS isomer reacted ca. 350 times faster than the RSRS isomer. RRSS-[Ni(tmc)](OTf) Na(OTf) has also been characterized, having crystallized in the monoclinic space group C2/c, with a = 24.690(23) Angstrom, b = 11.261(5) Angstrom, c = 9.681(6) Angstrom, beta = 91.03(4)degrees, V = 2691(2) Angstrom(3), and Z = 4. The macrocycle provides the Ni(I) ion with a square planar coordination environment in which there are two distinct Ni-N bond distances, 2.120(5) and 2.095(5) Angstrom. [References: 56]