Color Palette:
1. Color Name: Slate Gray
   Hex Code: 
          
          #708090
       
   Description: A deep and sophisticated gray tone resembling slate rocks.

2. Color Name: Silver
   Hex Code: 
          
          #C0C0C0
       
   Description: A light and elegant silver shade that adds a touch of luxury.

3. Color Name: Charcoal
   Hex Code: 
          
          #36454F
       
   Description: A dark and intense charcoal hue, perfect for creating contrast.

4. Color Name: Steel Blue
   Hex Code: 
          
          #4682B4
       
   Description: A cool and calming blue-gray color reminiscent of steel.

5. Color Name: Ash Gray
   Hex Code: 
          
          #B2BEB5
       
   Description: A soft and muted gray with a hint of warmth, like ash from a fire.

6. Color Name: Misty Gray
   Hex Code: 
          
          #BBBDC0
       
   Description: A light and airy gray tone that evokes a sense of tranquility and serenity.

This color palette of 6 shades with greyish tones is ideal for a professional and modern PowerPoint presentation featuring the New York skyline. The combination of deep grays, silver accents, and subtle blues creates a sophisticated and polished look that will enhance the visual appeal of your slides.