Reactivity of Carboranylacetylenes towards Cobalt Complexes

Abstract

The reaction of 1,6-diiodo-C 4 B 2 nido-carborane derivative 1 with RC 2 Li (R = Me, SPh) yields the corresponding carboranylacetylenes 2b,c. Treatment of the PPh 2 -substituted nidocarborane 3a with PhC 2 ZnCl in the presence of a catalytic amount of Pd(PPh 3 ) 4 leads to the known basal-substituted nido-carboranylacetylene 2a. The synthesis of apical-substituted compound 4b is achieved by the substitution of 3b by a Pd 0 -catalyzed Nigishi-type cross-coupling reaction; the basal boron atom is blocked by the n-butyl group. The 1,3-dicarboranyl-substituted (η 4 -cyclobutadiene)cobalt complexes 5a,c are obtained from the reactions of 2a,c with stoichiomet-

Carba-closo-dodecaborates with One or Two Alkynyl Substituents Bonded to Boron

“…Comparable values for d (CC) and d (B−CC) as observed for 1 and 6 have been reported for a variety of other boranes, borates, and carboranes with alkynyl groups bonded to boron, for example, for the [B(CCPh) 4 ] − anion, for 2,9-(Me 3 SiCC) 2 - closo -1,12-C 2 B 10 H 10 , and for the ortho -catecholato borane (C 6 H 4 O 2 )BCCPh (Table ).…”

“…In general, the δ( 3. 27,[59][60][61]63,69,70 Both 13 C nuclei of the alkynyl groups in the carba-closododecaborate anions couple to 11 B. The signals of the carbon nuclei of the carbon atoms that are bonded to boron are split into quartets with coupling constants of approximately 100 Hz (Table 3, Figure 5).…”

Low temperature in situ UV irradiation of [(η5-C5H5)Co(C2H4)2] in the NMR probe: formation of Co(iii) silyl hydride complexes

“…Clearly, only a very small amount of ethene is necessary to affect the position of equilibrium dramatically. The removal of the ethene shifts the equilibrium towards complex 6, according to eqn (2). The value of 2 J SiH in 6 was 50 ± 3 Hz and clearly lies outside the range associated with classical oxidative addition products.…”

Synthesis of Terpene and Steroid Dimers and Trimers Having Cyclobutadienyl−Co and Aromatic Tethers

“…The importance of the coordination of the alcohol to the cobalt and the steric bulkiness in the alkyne were additionally evaluated. Reaction of the bis-TMS-derivative 20 of mestranol with CpCo(CO) 2 resulted in recovery of starting material in all the conditions assayed, including an increase in the reaction temperature and an increase in the amount of CoCp(CO) 2 produces complex 22 (9%) together with methoxyestrone 16 as the main reaction product (48%; Scheme ).…”