Run visual studio as Administrator. and reference latest Newtonsof.Json package:
#I @"..\packages\Neo4jClient.1.0.0.652\lib\net40"
#I @"..\packages\Newtonsoft.Json.6.0.2\lib\net45"
#r "Neo4JClient.dll"
#r "Newtonsoft.Json.dll"
let client = new GraphClient(new Uri("http://host:7474/db/data"))
client.Connect()
printfn "conntected"