LIGAND VARIATION IN ALKYLIDENE COMPLEXES OF THE TYPE MO(CHR)(NR')(OR'')2

A variety of complexes of the type Mo(NR)2Cl2L2 (R = 4-Br-2,6-(i)Pr2-C6H2, 4-CN-2,6-(i)Pr2-C6H2, 3,5-Me2-C6H3, 2-(i)Pr-C6H4, 2-CF3-C6H4, 2-Ph-C6H4, and 1-adamantyl; L = 1/2 DME or pyridine) have been synthesized by treating [NH4]2[Mo2O7] with four equivalents of RNH2 in the presence of Me3SiCl and Et3N. They are readily alkylated by Grignard reagents to give complexes of the type Mo(NR)2(CH2R')2 (R=4-Br-2,6-(i)Pr2-C6H2, 4-CN-2,6-(i)Pr2-C6H2, 2,6-Me2-C6H3, 3,5-Me2-C6H3, 2-(t)Bu-C6H4, 2-(i)Pr-C6H4, 2-CF3-C6H4, 2-Ph-C6H4, 1-adamantyl, R'= (t)Bu or PhMe2C) from which alkylidene complexes of the type Mo(NR)(CHR')(OTf)2(DME) are formed upon addition of triflic acid. Addition of various alkoxides to the triflate complexes yields four-coordinate complexes of the type Mo(NR)(CHR')(OR')2 (combinations include R = 2,6-(i)Pr2-C6 H 3, 4-Br-2,6-(i)Pr2-C6H2, 4-CN-2,6-(i)Pr2-C6H2, 2,6-Me2-C6H3, 3,5-Me2-C6H3, 2-Bu-C6H4, 2-(i)Pr-C6H4, 2-CF3-C6H4, 2-Ph-C6H4, and 1-adamantyl; OR'' = OCMe3, OCEt3, 0-1-adamantyl, OCHMe2, OCMe2(CF3), OCMe(CF3)2, OC(CF3)3, and OC(CF3)2CF2CF2CF3).