Delta_G:
Make a union of your struct and an 8 byte char array.
Or cast to byte pointer; below will send the complete struct
Serial.write((byte*)&dataSend, sizeof(dataSend));
Why do you want to use Serial.write? Does the receiver expect binary data?
PS:
Your struct is called dataSent, not dataSend. And it does not have a member tempSend. Please be accurate.