Serialize/Deserialize complex Dictionary<ClassA><ClassB> by Newtonsoft JSON gives me errors while deserializing

Question

My JSON looks like:

[
  {
    "Key": {
      "PatientName": "Hans Gerd",
      "Alter": 81,
      "Geschlecht": "M",
      "Zimmernummer": 1,
      "PatientenLiegeplatz": 0,
      "IsDummyData": false
    },
    "Value": {
      "Puls": 0,
      "Temperatur": 0.0,
      "Systole": 0,
      "Diastole": 0,
      "DictationText": "",
      "Timestamp": "2021.05.24 12:31:06"
    }
  }
]

Serialization:

string json = JsonConvert.SerializeObject(saveObj.CareRoutineDataDictionary.ToArray(), Formatting.Indented);

How to Deserialize it? I have tried so much and it doesn't work. Common error Messages:

Unexpected character encountered while parsing value

If I try to do:

Dictionary<BasicPatientData, CareRoutineData> data = JsonConvert.DeserializeObject<Dictionary<BasicPatientData, CareRoutineData>>(File.ReadAllText(SaveFilePath));

I get an error:

JsonSerializationException: Cannot deserialize the current JSON array (e.g. [1,2,3]) into type 'System.Collections.Generic.Dictionary`2[BasicPatientData,CareRoutineData]' because the type requires a JSON object (e.g. {"name":"value"}) to deserialize correctly. To fix this error either change the JSON to a JSON object (e.g. {"name":"value"}) or change the deserialized type to an array or a type that implements a collection interface (e.g. ICollection, IList) like List that can be deserialized from a JSON array. JsonArrayAttribute can also be added to the type to force it to deserialize from a JSON array.

Can anyone help?