I don't think this is possible.
You can connect a pair of Cisco Nexus 5600 series switches in a vPC directly to another switch or to a server. vPC peer switches must be of the same type ((including same switch type, and LEM type). For example, you can connect a pair of Cisco Nexus 5600 series switches, but you cannot connect a Cisco Nexus 5600 series switch to a Cisco Nexus 6000 series switch, or a Cisco Nexus 5500 series switch in a vPC topology. For a Cisco Nexus 5696 switch, you can use Cisco Nexus 5600 LEMs as well as Cisco Nexus 6000 LEMs, but you cannot use different LEM versions in a vPC domain.
Link:
https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5600/sw/interfaces/7x/b_5600_Interfaces_Config_Guide_Release_7x/config_vpc.html?bookSearch=true#concept_F18E49F0E54E4D1BB61535C5FF313B74
HTH
