Few countries have invested more heavily in Russia than Germany has, rushing in to exploit new trade opportunities that opened up after the Cold War ended. More than 6,000 German companies set up operations there, and Russia became a major customer for German cars, pharmaceuticals and machinery. But now the rush is going in reverse. The announcement last week by the German chemical giant BASF that it had canceled a planned deal with Gazprom , the Russian energy giant, involving natural gas extraction and distribution, was the latest example of how German companies are delaying projects and investment. Opel, the car-making unit of G.M. based in Germany, has laid off workers at its plant in St. Petersburg; Volkswagen shut down an auto plant in Kaluga intermittently because of poor demand; and Fresenius, a health care company, canceled a joint venture with Russian partners. More than a third […]