Text-Zahl-Text in Gruppen zerlegen
// A12B --> A 12 B
// 12B --> NULL 12 B
// A12 --> A 12 NULL
// 12 --> NULL 12 NULL
// A --> A NULL NULL
Match m = Regex.Match(textToSplitt, @"(\p{L}*)(\d*)(\p{L}*)");
string text1 = m.Groups[1].Value;
string zahl = m.Groups[2].Value;
string text2 = m.Groups[3].Value;