Syntheses, structures, and reactivities of heteroleptic magnesium amide thiolates

The syntheses and characterizations of a family of novel heteroleptic magne sium amide thiolates are presented. The compounds are synthesized by ligand redistribution chemistry involving reactions of equimolar amounts of magne sium amides and magnesium thiolates. Utilization of the smaller thiolates [ Mg(SPh)(2)](n) and [Mg(S-2,4,6-(Pr3C6H2)-Pr-i)(2)](n) results in the isolat ion of dimeric species, [Mg(THF)(N(SiMe3)(2))(mu-SR)](2) (R = Ph (1), 2,4,6 -(Pr3C6H2)-Pr-i (2)), with four-coordinate metal centers and bridging thiol ate functions. The sterically more encumbered thiolate S-2,4,6-(Bu3C6H2)-Bu -t induces the formation of the four-coordinate, monomeric species Mg(THF)( 2)(N(SiMe3)(2))(S-2,4,6-(Bu3C6H2)-Bu-t) (3)). Careful choice of reaction co nditions allows the successful syntheses of pure heteroleptic compounds; ho wever, it remains difficult to obtain the compounds in high yields, since a tendency toward product symmetrization and ligand redistribution under re- formation of the starting materials is prevalent. One of these symmetrized products is also included in this report: the dimeric, four-coordinate magn esium thiolate [Mg(THF)(S-2,4,6-(Bu3C6H2)-Bu-t)(mu-S-2,4,6-(Bu3C6H2)-Bu-t)] (2) (4), isolated as the product of the reaction between [Mg-(N(SiMe3)(2))( 2)](2) and Mg(THF)(2)(S-2,4,6-(Bu3C6H2)-Bu-t)(2). All compounds were charac terized by NMR and IR spectroscopy, elemental analyses, and X-ray crystallo graphy. Crystal data obtained with Mo Ka (lambda = 0.710 73 Angstrom) radia tion are as follows. 1: C16H31MgNOSSi2, a = 11.2100(1) Angstrom, b = 17.451 2(3) Angstrom, c = 11.2999(2) Angstrom, beta = 97.952(1)degrees, V = 2189.3 2(6) Angstrom(3), 2 4,monoclinic, space group P2(1)/n, R1 (all data) = 0.09 34.2: C25H49MgNOSSi2, a = 11.1691(1) Angstrom, b = 11.0578(1) Angstrom, c = 26.0671(4) Angstrom, beta = 99.906(1)degrees V = 3171.44(6) Angstrom(3) Z = 4, monoclinic, space group P2(1)/c, R1 (all data) = 0.0557. 3: C36H71MgNO 3SSi2, a = 42.8293(16) Angstrom, b = 10.9737(5) Angstrom, c = 16.8305(7) An gstrom, beta = 98.755(3)degrees, V = 7818.1(6) Angstrom(3), Z = 8, monoclin ic, space group C2/c, R1 (all data) = 0.1331. 4: C80H132Mg2O2S4, a = 18.880 6(2) Angstrom, b = 19.3850(2) Angstrom, c = 27.3012(4) Angstrom, beta = 97. 250(1)degrees, V = 9912.4(2) Angstrom(3), Z = 4, 16.8305(7) Angstrom, monoc linic, space group P2(1)/n, R1 (all data) = 0.1023.