Table 1 Screening of cobalt(II) complexes as potential (pre)catalysts.

From: Synthesis of diarylmethanes by means of Negishi cross-coupling enabled by cobalt-solvent coordination

#

Catalyst

Conv. of 2 b)

Selectivity b)

3

4

Other c)

1

[CoBr2(PPh3)2]

70

38

38

24

2

[CoCl2(PPh3)2]

41

30

44

26

3

[CoBr2(2-Me-py)2]

53

27

44

29

4

[CoBr2(dppe)]

56

37

45

18

5

CoCl2

42

65

18

17

6

CoBr2

79

81

7

12

7

[CoCl2(2-Me-py)2]

57

17

48

35

8

[CoCl2(bipicoline)]

69

28

45

27

9

none

0

-

-

-

  1. (a) Conditions: 0.4 M in THF, 40 °C, 20 h [BnZnBr]: [4-MeC6H4I]: [Co] = 2 : 1 : 0.05; (b) determined by GC-MS; (c) 5 and toluene as product of possible demetalation of 1 and/or dehalogenation of 2.
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