Medium size macrocycles incorporating combinations of coordinated-1,3-diyne units, oxygen donors and group 14 elements

Abstract Two approaches have been employed to prepare medium size macrocycles incorporating combinations of coordinated-1,3-diyne units, oxygen donors and group 14 elements. In the first approach, the acid-catalysed reaction of [{Co 2 (CO) 6 (μ-η 2 -HOCH 2 C C )} 2 ] ( 1a ) with either C 6 H 5 OH, C 6 H 4 -1,4-(OH) 2 or C 6 H 4 -1,2-(OH) 2 was found to form in good to moderate yield the nine-membered [{Co 2 (CO) 6 } 2 { cyclo -μ-η 2 :μ-η 2 -CH 2 C 2 C 2 CH 2 OC 6 H 4 } 2 ] ( 2 ) and the eight-membered macrocycles, [{Co 2 (CO) 6 } 2 { cyclo -μ-η 2 :μ-η 2 -CH 2 C 2 C 2 CH 2 -2,3-C 6 H 2 -1,4-(OH) 2 }] ( 3 ) and [{Co 2 (CO) 6 } 2 { cyclo -μ-η 2 :μ-η 2 -CH 2 C 2 C 2 CH 2 -3,4-C 6 H 2 -1,2-(OH) 2 }] ( 4 ), respectively. In contrast, treatment of the bis-lithiated derivative of 1a with Cl 2 SiR 1 R 2 affords the silicon-containing nine-membered macrocycles [{Co 2 (CO) 6 } 2 { cyclo -μ-η 2 :μ-η 2 -OCH 2 C 2 C 2 CH 2 OSiR 1 R 2 }] ( 5a R 1  = R 2  = Me; 5b R 1  = R 2  = Ph; 5c R 1  = Me, R 2  = Ph). Similarly, the germanium analogue of 5b , [{Co 2 (CO) 6 } 2 { cyclo -μ-η 2 :μ-η 2 -OCH 2 C 2 C 2 CH 2 OGePh 2 }] ( 6 ) can be prepared from Cl 2 GePh 2 . Single crystal X-ray diffraction studies have been reported on 2 , 3 , 5a , 5b and 6 .