Woocommerce rest API variations attributes

I'm trying to send a new variation to a Woocommerce product. It is correctly created except for the attribute.

I'm sending:

$data = ['sku'=> $confezione['CODART'],'price'         => $confezione['PREZZO1'],'regular_price' => $confezione['PREZZO1'],'attributes'    => [        ['id'        =>  3,'name'      =>  'confezionamento','slug'      =>  'pa_confezionamento','options'   =>  $tipo         ]  ]];

and the [attributes] is empty

If I compile the variation manually the following attribute is created:

    [attributes] => Array        (            [0] => stdClass Object                (                    [id] => 3                    [name] => confezionamento                    [slug] => pa_confezionamento                    [option] => FL 12 x 1 lt                )        )

the attributes in product are:

    [attributes] => Array        (            [0] => stdClass Object                (                    [id] => 3                    [name] => confezionamento                    [slug] => pa_confezionamento                    [position] => 0                    [visible] => 1                    [variation] => 1                    [options] => Array                        (                            [0] => FL 12 x 1 lt                            [1] => FL 12 x 750 ml                            [2] => TA 10 lt                            [3] => TA 20 lt                            [4] => TA 4 x 5 lt                        )                )        )

Where is my mistake?