Problems with i2c in esp8266 (MPU9250 [GY-91])

I'm trying to call WHO_AM_I, don't know if this is the correct way to read data, but this is how it works the module, the example in page doesn't explain well, I mean, how to read 8 bits from device 0x68 to the address 0x75 :

I2C1.setup( {scl: NodeMCU.D4, sda: NodeMCU.D5} );

I2C1.writeTo(0x68,0x75);
var data = I2C1.readFrom(0x75,8);
console.log(data);

But still got the same error:

Uncaught InternalError: I2CRead: No ACK 0
 at line 5 col 33
  var data = I2C1.readFrom(0x3B,8);
                                ^
in function called from system