[[alternative]]Synthesis and Characterization of Group 6 (M= Cr, Mo) Carbonyl Chalcogenides Complexes

[[abstract]][1] Se-Cr system Reflux of Se powder or SeO2、SeO32- with Cr(CO)6、Et4NBr in KOH/MeOH solution yields the closo-cluster [Et4N]2[Se2Cr3(CO)10]. [S2Cr3(CO)10]2- also an be prepared in the similar conditions. Further methylation of [Se2Cr3(CO)10]2- with MeSO3CF3 produces the selenium-methylated complex [MeSe{Cr(CO)5}3]- and {MeSeCr(CO)4}2 . However, the reactions of [Se2Cr3(CO)10]2- with RX (R = C3H3, X = Cl, Br; R = CH3, X = I) form the known mononuclear compounds [XCr(CO)5]- (X = Cl, Br, I) Further, reaction of [Se2Cr3(CO)10]2- with Fe(CO)5/KOH gives [SeFe3(CO)9]2-, while treatment with Ru3(CO)12 produces the octahedral complexes [HSe2Ru4(m-CO)2(CO)8]- and [Se2Ru4(m-CO)4(CO)8]2-. Be- sides, [Se2Cr3(CO)10]2- can react with 1 equiv. of Mo(CO)6 in acetone to produce the mixed-metal Cr/Mo cluster [Se2MoCr2(CO)10]2-. On the other hand, reaction of [Se2Cr3(CO)10]2- with excess Mo(CO)6 leads to formation of [Se2Mo3(CO)10]2- in good yield. When [Se2Cr3(CO)10]2- was treated with Mn(CO)5Br in acetone at room temperature, two different types of the unusual mixed-metal clusters [Me2CSe2Cr2Mn(CO)14]- and [Se2Cr2Mn3- (CO)20]- were produced. [2] Te-Cr system The reaction of Te powder with Cr(CO)6/KOH in a molar ratio of 1:2 in methanol solution forms [HTe{Cr(CO)5}2]- , which can rapidly transform into a highly reactive species [Et4N]2[Te{Cr(CO)5}2] by the addition of Et4NBr . However, the mono-methylated complex [MeTe{Cr(CO)5}2]- can be obtained by using NaOH under the similar conditions, where the methyl group is likely to come from the methanol solvent. The reaction of [Te{Cr(CO)5}2]2- with MeSO3CF3 only affords the double-methylated complex Me2Te{Cr(CO)5}2 . [Te{Cr(CO)5}2]2- rapidly transforms to give [X{TeCr2(CO)10}2]2- (X = O, CH2) upon the attack of O2 and CH2Cl2. Besides, the reaction of [Te{Cr(CO)5}2]2- with Cu(CH3CN)4BF4 produces the known compound [Te2Cr4(CO)20]2- while treatment of [Te{Cr(CO)5}2]2- with NaOH/MeOH gives another known compound [Te2Cr4(CO)18]2-. When Te powder reacts with Cr(CO)6/KOH in a molar ratio of 1: 3 in methanol solution, the product is found to rapidly transform into a new complex [CH2ClTe{Cr(CO)5}3]- upon the addition of CH2Cl2. [3] Te-Mo system Reflux of Te powder and Mo(CO)6 in KOH/MeOH solution forms the tire-shaped cluster [Te8Mo6(CO)18]2-, which contains three Te2Mo2 planes linking by Te22- group. This product can be also obtained from the reaction of Te powder with [Te2Mo4(CO)18]2- in the basic alcoholic solution. When [Te2Mo4(CO)18]2- was treated with H2C=CHCH2Br, the double-substituted complex [(C3H5)2Te2Mo2(CO)6] was obtained where the Mo(CO)5 moiety of [Te2Mo4(CO)18]2- is replaced by the incoming C3H5 group. The study herein describes the similarities and differences among the reactions of group 6 (Cr, Mo) carbonyls with group 16 chalcogen atoms (S, Se, Te) and discusses as well the effect of basicity and metal size on cluster formation.