Carbonylchromium Monotelluride Complexes [Et₄N]₂[Te{Cr(CO)₅}_n] (n = 2, 3):  Two Important Intermediates

Abstract

The first isolation of the monotelluride-bridged chromium carbonyl complexes [Et 4 N] 2 [Te-{Cr(CO)has been achieved from the reaction of Te powder with 3 equiv of Cr(CO) 6 in the presence of [Et 4 N]Br in concentrated KOH/EtOH solution. According to X-ray analysis, anion 1 displays a pyramidal geometry with the Te atom bonded to three Cr(CO) 5 fragments and anion 2 exhibits a nonlinear structure with the Te atom coordinated with two Cr(CO) 5 moieties. Complex 1 can transform to 2 in the presence of Cr(CO) 6 /KOH/EtOH solution. Conversely, 2 can convert back to 1 upon the reaction with Cr(CO) 6 in MeCN. Interestingly, the novel C-O activation of MeOH is observed when 1 was treated with NaOH/MeOH solution at 70 °C, giving the Te-methylated product [Et 4 N][MeTe{Cr(CO) 5 } 2 ] ([Et 4 N][3]). Complex 2 is reactive toward some organic solvents. It can react with CH 2 Cl 2 to form the CH 2 -bridged tetrachromium complex [Et 4 N] 2 [CH 2 {TeCr 2 -(CO) 10 } 2 ] ([Et 4 N] 2 [4]) and can transform to the known tetrachromium tritelluride complex [Et 4 N] 2 [Te 3 {Cr(CO) 5 } 4 ], in MeOH solution. Besides, we also found that 2 can undergo oxidative coupling with [Cu(MeCN) 4 ]BF 4 in MeOH to form the dimeric open cluster [Te 2 {Cr(CO) 5 } 4 ] 2and can react with NaOH in MeOH to give the dimeric ring complex [Te 2 Cr 4 (CO) 18 ] 2-.Complexes 1-4 are fully characterized by spectroscopic methods and singlecrystal X-ray analysis. This paper describes that complexes 1 and 2 are important intermediates for a series of tellurium-containing polychromium complexes, and the interesting structural features of the resultant new polychromium carbonyl complexes are compared as well.

New Strategy to Mixed-Group 6 Metal Carbonyl Telluride Complexes: Completion of the Trigonal Bipyramidal Clusters [Te2CrM2(CO)10]2- (M = Cr, Mo, W)

“…Elemental analyses of C, H, and N were performed on a Perkin-Elmer 2400 analyzer at the NSC Regional Instrumental Center at National Taiwan University, Taipei, Taiwan. [Et 4 N] 2 [Te{Cr(CO) 5 } 2 ] and [Et 4 N] 2 [Te 2 Cr 4 (CO) 18 ] ([Et 4 N] 2 [ 1a ]) were prepared according to the published procedures …”

“…The residue was washed with Et 2 O−CH 2 Cl 2 and extracted with THF to give 0.27 g (0.21 mmol) of an orange sample of [Et 4 N] 2 [Te 2 Cr 2 Mo 2 (CO) 18 ] ([Et 4 N] 2 [ 1b ]) (68% based on [Et 4 N] 2 [Te{Cr(CO) 5 } 2 ]). The CH 2 Cl 2 washing solution was identified by IR to contain [Et 4 N] 2 [Te{Cr(CO) 5 } 3 ] . [Et 4 N] 2 [ 1b ] is soluble in THF, MeCN, and acetone.…”

“…Chalcogenide ligands have been proven to be useful stabilizing ligands for the construction of the transition metal carbonyl clusters; however, group 6 metal-containing chalcogenides were much less explored. − We have reported the synthesis of the novel Se-capped trichromium carbonyl closo -cluster [Se 2 Cr 3 (CO) 10 ] 2- and its subsequent metal substitution reaction to give the mixed Cr−Mo analogous cluster . However, the analogous tellurium clusters remained unknown mainly due to the weak bonds of Te−group 6 metal and lack of the synthetic methodology. , The tellurides are expected to possess versatile bonding modes and promote chemical and physical properties due to their larger size, increased nucleophilicity, and better metallic character.…”

“…The previous study showed that the open monotelluride-bridged dichromium complex [Te{Cr(CO) 5 } 2 ] 2- could be obtained from a route similar to that for the closo -cluster [Se 2 Cr 3 (CO) 10 ] 2- . The interesting question arises whether this open-structural complex [Te{Cr(CO) 5 } 2 ] 2- can be used as the building block for the construction of heteronuclear transition metal clusters.…”

Carbonyl Chalcogenides Clusters Existing as Disguised Forms of Hydrocarbon Isomers

“…In this paper, the method is being applied to analyze carbonyl chalcogenide complexes. The examples have been selected from various literature sources (Shieh, et al, 2003;Shieh, et al, 2012;Harlan, et al, 1996;Das, et al, 1997). The results of the samples analyzed are given in Table 1.…”