West German Chancellor Helmut Kohl, seeking improved economic relations with the Soviets, met Monday with Mikhail Gorbachev for their first formal talks since Gorbachev became Soviet leader. Kohl, who arrived in Moscow for a four-day official visit, was greeted at Vnukovo airport by Premier Nikolai I. Ryzhkov, Foreign Minister Eduard A. Shevardnadze and Defense Minister Dmitri T. Yazov, the official news agency Tass said. The West German and his wife, Hannelore, were received by Gorbachev and his wife, Raisa, in St. George's Hall of the Kremlin, Tass said. The two leaders then held talks in St. Catherine's Hall, the agency said. Foreign Minister Hans-Dietrich Genscher, Defense Minister Rupert Scholz and other Cabinet members were in the West German delegation that accompanied Kohl from Bonn.